feat: Add persistent storage support for Redis and APCu (v0.4.0)

- Add StorageFactory class for storage adapter selection with fallback
- Support Redis storage for shared metrics across instances
- Support APCu storage for high-performance single-server deployments
- Add Storage tab in admin settings with configuration UI
- Add connection testing for Redis and APCu adapters
- Support environment variables for Docker/containerized deployments
- Update Collector to use StorageFactory instead of hardcoded InMemory
- Add all translations (English and German)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,82 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.4.0] - 2026-02-02
+
+### Added
+
+- Persistent Storage Support:
+  - Redis storage adapter for shared metrics across multiple instances
+  - APCu storage adapter for single-server high-performance caching
+  - StorageFactory class for automatic adapter selection and fallback
+  - Connection testing with detailed error messages
+- New "Storage" tab in admin settings:
+  - Storage adapter selection (In-Memory, Redis, APCu)
+  - Redis configuration (host, port, password, database, key prefix)
+  - APCu configuration (key prefix)
+  - Connection test button
+  - Environment variables documentation
+- Environment variable configuration for Docker/containerized environments:
+  - `WP_PROMETHEUS_STORAGE_ADAPTER` - Select storage adapter
+  - `WP_PROMETHEUS_REDIS_HOST` - Redis server hostname
+  - `WP_PROMETHEUS_REDIS_PORT` - Redis server port
+  - `WP_PROMETHEUS_REDIS_PASSWORD` - Redis authentication
+  - `WP_PROMETHEUS_REDIS_DATABASE` - Redis database index (0-15)
+  - `WP_PROMETHEUS_REDIS_PREFIX` - Redis key prefix
+  - `WP_PROMETHEUS_APCU_PREFIX` - APCu key prefix
+- Automatic fallback to In-Memory storage if configured adapter fails
+- Docker Compose example in admin settings
+
+### Changed
+
+- Settings page now has 6 tabs: License, Metrics, Storage, Custom Metrics, Dashboards, Help
+- Updated translations with all new strings (English and German)
+- Collector now uses StorageFactory for storage adapter instantiation
+
+## [0.3.0] - 2026-02-02
+
+### Added
+
+- Custom Metrics Builder:
+  - Admin UI to define custom gauge metrics
+  - Support for static values and WordPress option-based values
+  - Label support with up to 5 labels and 50 value combinations
+  - Metric validation following Prometheus naming conventions
+- Metric Export/Import:
+  - JSON-based configuration export for backup
+  - Import with three modes: skip existing, overwrite, or rename duplicates
+  - Version tracking in export format
+- Grafana Dashboard Templates:
+  - WordPress Overview dashboard (users, posts, comments, cron, transients)
+  - WordPress Runtime dashboard (HTTP requests, database queries)
+  - WordPress WooCommerce dashboard (orders, revenue, products, customers)
+  - Easy download and import instructions
+- New "Custom Metrics" tab in admin settings
+- New "Dashboards" tab in admin settings
+- Reset runtime metrics button to clear accumulated data
+
+### Changed
+
+- Settings page now has 5 tabs: License, Metrics, Custom Metrics, Dashboards, Help
+- Updated translations with all new strings
+
+## [0.2.2] - 2026-02-02
+
+### Fixed
+
+- Fixed `wc_orders_count()` call missing required status parameter in WooCommerce orders metrics
+
+## [0.2.1] - 2026-02-02
+
+### Added
+
+- Localhost license bypass for development environments (localhost, 127.0.0.1, ::1, \*.localhost, \*.local)
+- Automatic rewrite rules flush when license status changes
+
+### Fixed
+
+- Fixed 404 error on `/metrics` endpoint when license becomes valid after plugin activation
+
 ## [0.2.0] - 2026-02-02
 
 ### Added

CLAUDE.md

@@ -18,6 +18,9 @@ This plugin provides a Prometheus `/metrics` endpoint and an extensible way to a
 - Cron job metrics (scheduled events, overdue, next run)
 - Transient cache metrics (total, expiring, expired)
 - WooCommerce integration (products, orders, revenue, customers)
+- Custom metric builder with admin UI (gauges with static or option-based values)
+- Metric export/import for backup and site migration
+- Grafana dashboard templates for easy visualization
 - Dedicated plugin settings under 'Settings/Metrics' menu
 - Extensible by other plugins using `wp_prometheus_collect_metrics` action hook
 - License management integration
@@ -30,11 +33,7 @@ This project is proudly **"vibe-coded"** using Claude.AI - the entire codebase w
 
 **Note for AI Assistants:** Clean this section after the specific features are done or new releases are made. Effective changes are tracked in `CHANGELOG.md`. Do not add completed versions here - document them in the Session History section at the end of this file.
 
-### Version 0.3.0 (Planned)
+*No planned features at this time.*
-
-- Custom metric builder in admin
-- Metric export/import
-- Grafana dashboard templates
 
 ## Technical Stack
 
@@ -214,6 +213,10 @@ wp-prometheus/
 │   └── release.yml          # CI/CD pipeline
 ├── assets/
 │   ├── css/                  # Admin/Frontend styles
+│   ├── dashboards/           # Grafana dashboard templates
+│   │   ├── wordpress-overview.json
+│   │   ├── wordpress-runtime.json
+│   │   └── wordpress-woocommerce.json
 │   └── js/
 │       └── admin.js          # Admin JavaScript
 ├── languages/                # Translation files
@@ -222,6 +225,7 @@ wp-prometheus/
 ├── releases/                 # Release packages
 ├── src/
 │   ├── Admin/
+│   │   ├── DashboardProvider.php # Grafana dashboard provider
 │   │   └── Settings.php      # Settings page
 │   ├── Endpoint/
 │   │   └── MetricsEndpoint.php  # /metrics endpoint
@@ -229,7 +233,9 @@ wp-prometheus/
 │   │   └── Manager.php       # License management
 │   ├── Metrics/
 │   │   ├── Collector.php        # Prometheus metrics collector
-│   │   └── RuntimeCollector.php # Runtime metrics collector
+│   │   ├── CustomMetricBuilder.php # Custom metric CRUD
+│   │   ├── RuntimeCollector.php # Runtime metrics collector
+│   │   └── StorageFactory.php   # Storage adapter factory
 │   ├── Installer.php         # Activation/Deactivation
 │   ├── Plugin.php            # Main plugin class
 │   └── index.php
@@ -285,6 +291,65 @@ add_action( 'wp_prometheus_collect_metrics', function( $collector ) {
 
 ## Session History
 
+### 2026-02-02 - Persistent Storage (v0.4.0)
+
+- Added persistent storage support for metrics:
+  - `StorageFactory.php` - Factory class for storage adapter instantiation
+  - Redis storage adapter for shared metrics across multiple instances
+  - APCu storage adapter for single-server high-performance caching
+  - Automatic fallback to In-Memory if configured adapter fails
+- Added new "Storage" tab in admin settings:
+  - Storage adapter selection (In-Memory, Redis, APCu)
+  - Redis configuration (host, port, password, database, key prefix)
+  - APCu configuration (key prefix)
+  - Connection test button with detailed error messages
+- Added environment variable support for Docker deployments:
+  - `WP_PROMETHEUS_STORAGE_ADAPTER` - Adapter selection
+  - `WP_PROMETHEUS_REDIS_HOST`, `_PORT`, `_PASSWORD`, `_DATABASE`, `_PREFIX`
+  - `WP_PROMETHEUS_APCU_PREFIX`
+  - Environment variables take precedence over admin settings
+- Updated `Collector.php` to use `StorageFactory::get_adapter()`
+- Updated Help tab with storage backends documentation
+- Updated translation files with all new strings
+- **Key Learning**: promphp/prometheus_client_php storage adapters
+  - Redis adapter requires options array with host, port, password, timeout
+  - APCu adapter just needs a prefix string
+  - Use `Redis::setPrefix()` before instantiation for custom key prefixes
+- **Key Learning**: Docker environment variable configuration
+  - Use `getenv()` with explicit false check (`false !== getenv()`)
+  - Environment variables should override WordPress options for containerized deployments
+
+### 2026-02-02 - Custom Metrics & Dashboards (v0.3.0)
+
+- Added Custom Metric Builder with full admin UI:
+  - `CustomMetricBuilder.php` - CRUD operations, validation, export/import
+  - Support for static values and WordPress option-based values
+  - Label support (max 5 labels, 50 value combinations)
+  - Prometheus naming convention validation (`[a-zA-Z_:][a-zA-Z0-9_:]*`)
+- Added Grafana Dashboard Templates:
+  - `DashboardProvider.php` - Dashboard file provider with path traversal protection
+  - `wordpress-overview.json` - General WordPress metrics
+  - `wordpress-runtime.json` - HTTP/DB performance metrics
+  - `wordpress-woocommerce.json` - WooCommerce store metrics
+- Added export/import functionality:
+  - JSON-based configuration export
+  - Three import modes: skip, overwrite, rename duplicates
+  - Version tracking in export format
+- Updated Settings page with new tabs:
+  - "Custom Metrics" tab with metric form and table
+  - "Dashboards" tab with download buttons
+  - "Reset Runtime Metrics" button in Metrics tab
+- Updated `Collector.php` to integrate custom metrics
+- Updated translation files with all new strings
+- **Key Learning**: Dynamic form handling in WordPress admin
+  - Use `wp_create_nonce()` with unique nonce names per AJAX action
+  - Localize script with `wp_localize_script()` for nonces and AJAX URL
+  - Always verify `current_user_can('manage_options')` in AJAX handlers
+- **Key Learning**: Grafana dashboard JSON format
+  - Use `${DS_PROMETHEUS}` for data source variable
+  - Schema version 39 for current Grafana compatibility
+  - Panels use `gridPos` for layout positioning
+
 ### 2026-02-02 - Extended Metrics (v0.2.0)
 
 - Added WooCommerce integration metrics (only when WooCommerce is active):

PLAN.md

@@ -59,6 +59,7 @@ wp-prometheus/
 │   └── release.yml          # CI/CD pipeline
 ├── assets/
 │   ├── css/                  # Admin/Frontend styles
+│   ├── dashboards/           # Grafana dashboard templates
 │   └── js/
 │       └── admin.js          # Admin JavaScript
 ├── languages/                # Translation files
@@ -67,13 +68,17 @@ wp-prometheus/
 ├── releases/                 # Release packages
 ├── src/
 │   ├── Admin/
+│   │   ├── DashboardProvider.php
 │   │   └── Settings.php
 │   ├── Endpoint/
 │   │   └── MetricsEndpoint.php
 │   ├── License/
 │   │   └── Manager.php
 │   ├── Metrics/
-│   │   └── Collector.php
+│   │   ├── Collector.php
+│   │   ├── CustomMetricBuilder.php
+│   │   ├── RuntimeCollector.php
+│   │   └── StorageFactory.php
 │   ├── Installer.php
 │   ├── Plugin.php
 │   └── index.php
@@ -159,13 +164,57 @@ Alternatively, the token can be passed as a query parameter (for testing):
 https://example.com/metrics/?token=your-auth-token
 ```
 
+## Storage Configuration
+
+The plugin supports multiple storage backends for Prometheus metrics:
+
+### Available Adapters
+
+| Adapter   | Description                     | Use Case                              |
+| --------- | ------------------------------- | ------------------------------------- |
+| In-Memory | Default, no persistence         | Development, single request metrics   |
+| Redis     | Shared storage across instances | Production, load-balanced environments|
+| APCu      | High-performance local cache    | Production, single-server deployments |
+
+### Environment Variables
+
+For Docker or containerized environments, configure storage via environment variables:
+
+```bash
+# Storage adapter selection
+WP_PROMETHEUS_STORAGE_ADAPTER=redis
+
+# Redis configuration
+WP_PROMETHEUS_REDIS_HOST=redis
+WP_PROMETHEUS_REDIS_PORT=6379
+WP_PROMETHEUS_REDIS_PASSWORD=secret
+WP_PROMETHEUS_REDIS_DATABASE=0
+WP_PROMETHEUS_REDIS_PREFIX=WORDPRESS_PROMETHEUS_
+
+# APCu configuration
+WP_PROMETHEUS_APCU_PREFIX=wp_prom
+```
+
+### Docker Compose Example
+
+```yaml
+services:
+  wordpress:
+    image: wordpress:latest
+    environment:
+      WP_PROMETHEUS_STORAGE_ADAPTER: redis
+      WP_PROMETHEUS_REDIS_HOST: redis
+      WP_PROMETHEUS_REDIS_PORT: 6379
+    depends_on:
+      - redis
+
+  redis:
+    image: redis:alpine
+```
+
 ## Future Enhancements
 
-### Version 0.3.0
+*No planned features at this time.*
-
-- Custom metric builder in admin
-- Metric export/import
-- Grafana dashboard templates
 
 ## Dependencies
 

assets/css/admin.css

@@ -45,3 +45,163 @@
 .wp-prometheus-tab-content .form-table {
     margin-top: 10px;
 }
+
+/* Custom metrics form */
+.wp-prometheus-metric-form {
+    background: #fff;
+    border: 1px solid #ccd0d4;
+    border-radius: 4px;
+    padding: 20px;
+    margin: 20px 0;
+}
+
+.wp-prometheus-metric-form h3 {
+    margin-top: 0;
+    padding-bottom: 10px;
+    border-bottom: 1px solid #eee;
+}
+
+.wp-prometheus-metric-form .required {
+    color: #d63638;
+}
+
+/* Label rows */
+.metric-label-row {
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    margin-bottom: 8px;
+}
+
+.metric-label-row input {
+    flex: 1;
+    max-width: 300px;
+}
+
+.metric-label-row .remove-label {
+    padding: 0 8px;
+    min-width: auto;
+}
+
+/* Value rows */
+.metric-value-row {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    margin-bottom: 8px;
+    flex-wrap: wrap;
+}
+
+.metric-value-row input {
+    width: 120px;
+}
+
+.metric-value-row .remove-value-row {
+    padding: 0 8px;
+    min-width: auto;
+}
+
+/* Custom metrics table */
+.wp-prometheus-custom-metrics .wp-list-table code {
+    background: #f0f0f1;
+    padding: 2px 6px;
+    border-radius: 3px;
+}
+
+.wp-prometheus-custom-metrics .wp-list-table td {
+    vertical-align: middle;
+}
+
+.wp-prometheus-custom-metrics .wp-list-table .dashicons {
+    font-size: 18px;
+    width: 18px;
+    height: 18px;
+}
+
+/* Dashboard grid */
+.wp-prometheus-dashboard-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
+    gap: 20px;
+    margin: 20px 0;
+}
+
+.wp-prometheus-dashboard-card {
+    background: #fff;
+    border: 1px solid #ccd0d4;
+    border-radius: 4px;
+    padding: 20px;
+    text-align: center;
+    transition: box-shadow 0.2s ease;
+}
+
+.wp-prometheus-dashboard-card:hover {
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+}
+
+.wp-prometheus-dashboard-card .dashboard-icon {
+    margin-bottom: 15px;
+}
+
+.wp-prometheus-dashboard-card .dashboard-icon .dashicons {
+    font-size: 48px;
+    width: 48px;
+    height: 48px;
+    color: #2271b1;
+}
+
+.wp-prometheus-dashboard-card h3 {
+    margin: 0 0 10px 0;
+    font-size: 16px;
+}
+
+.wp-prometheus-dashboard-card p {
+    color: #646970;
+    margin: 0 0 15px 0;
+    font-size: 13px;
+}
+
+/* Import options panel */
+#import-options {
+    border-radius: 4px;
+}
+
+#import-options label {
+    display: block;
+    margin-bottom: 8px;
+}
+
+/* Spinner alignment */
+.spinner {
+    float: none;
+    vertical-align: middle;
+}
+
+/* Button groups */
+.wp-prometheus-tab-content .button + .button {
+    margin-left: 5px;
+}
+
+/* Notice messages in forms */
+.wp-prometheus-metric-form .notice,
+.wp-prometheus-custom-metrics .notice {
+    margin: 10px 0;
+    padding: 10px 15px;
+}
+
+/* Responsive adjustments */
+@media screen and (max-width: 782px) {
+    .wp-prometheus-dashboard-grid {
+        grid-template-columns: 1fr;
+    }
+
+    .metric-value-row {
+        flex-direction: column;
+        align-items: flex-start;
+    }
+
+    .metric-value-row input {
+        width: 100%;
+        max-width: none;
+    }
+}

assets/dashboards/wordpress-overview.json

@@ -0,0 +1,851 @@
+{
+  "annotations": {
+    "list": []
+  },
+  "editable": true,
+  "fiscalYearStartMonth": 0,
+  "graphTooltip": 0,
+  "id": null,
+  "links": [],
+  "panels": [
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 0
+      },
+      "id": 1,
+      "panels": [],
+      "title": "System Info",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 0,
+        "y": 1
+      },
+      "id": 2,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "/^version$/",
+          "values": false
+        },
+        "textMode": "value"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_info",
+          "format": "table",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "WordPress Version",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 6,
+        "y": 1
+      },
+      "id": 3,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "/^php_version$/",
+          "values": false
+        },
+        "textMode": "value"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_info",
+          "format": "table",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "PHP Version",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 12,
+        "y": 1
+      },
+      "id": 4,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_users_total)",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Total Users",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 18,
+        "y": 1
+      },
+      "id": 5,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_plugins_total{status=\"active\"}",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Active Plugins",
+      "type": "stat"
+    },
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 5
+      },
+      "id": 6,
+      "panels": [],
+      "title": "Content",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            }
+          },
+          "mappings": []
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 0,
+        "y": 6
+      },
+      "id": 7,
+      "options": {
+        "legend": {
+          "displayMode": "list",
+          "placement": "right",
+          "showLegend": true
+        },
+        "pieType": "pie",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_users_total",
+          "instant": true,
+          "legendFormat": "{{role}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Users by Role",
+      "type": "piechart"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            }
+          },
+          "mappings": []
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 8,
+        "y": 6
+      },
+      "id": 8,
+      "options": {
+        "legend": {
+          "displayMode": "list",
+          "placement": "right",
+          "showLegend": true
+        },
+        "pieType": "pie",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_posts_total{post_type=\"post\"}",
+          "instant": true,
+          "legendFormat": "{{status}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Posts by Status",
+      "type": "piechart"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            }
+          },
+          "mappings": []
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 16,
+        "y": 6
+      },
+      "id": 9,
+      "options": {
+        "legend": {
+          "displayMode": "list",
+          "placement": "right",
+          "showLegend": true
+        },
+        "pieType": "pie",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_comments_total{status!=\"total_comments\"}",
+          "instant": true,
+          "legendFormat": "{{status}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Comments by Status",
+      "type": "piechart"
+    },
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 14
+      },
+      "id": 10,
+      "panels": [],
+      "title": "System Health",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "yellow",
+                "value": 5
+              },
+              {
+                "color": "red",
+                "value": 10
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 0,
+        "y": 15
+      },
+      "id": 11,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_cron_overdue_total",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Overdue Cron Events",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 6,
+        "y": 15
+      },
+      "id": 12,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_cron_events_total)",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Total Cron Events",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 12,
+        "y": 15
+      },
+      "id": 13,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_transients_total{type=\"total\"}",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Total Transients",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "yellow",
+                "value": 50
+              },
+              {
+                "color": "red",
+                "value": 100
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 6,
+        "x": 18,
+        "y": 15
+      },
+      "id": 14,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_transients_total{type=\"expired\"}",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Expired Transients",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "bars",
+            "fillOpacity": 80,
+            "gradientMode": "none",
+            "hideFrom": {
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+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "auto",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
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+        "w": 24,
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+        "y": 19
+      },
+      "id": 15,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "list",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "topk(10, wordpress_cron_events_total)",
+          "instant": false,
+          "legendFormat": "{{hook}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Top 10 Cron Hooks",
+      "type": "timeseries"
+    }
+  ],
+  "refresh": "30s",
+  "schemaVersion": 39,
+  "tags": ["wordpress", "prometheus"],
+  "templating": {
+    "list": [
+      {
+        "current": {
+          "selected": false,
+          "text": "Prometheus",
+          "value": "Prometheus"
+        },
+        "hide": 0,
+        "includeAll": false,
+        "label": "Data Source",
+        "multi": false,
+        "name": "DS_PROMETHEUS",
+        "options": [],
+        "query": "prometheus",
+        "queryValue": "",
+        "refresh": 1,
+        "regex": "",
+        "skipUrlSync": false,
+        "type": "datasource"
+      }
+    ]
+  },
+  "time": {
+    "from": "now-6h",
+    "to": "now"
+  },
+  "timepicker": {},
+  "timezone": "browser",
+  "title": "WordPress Overview",
+  "uid": "wp-prometheus-overview",
+  "version": 1,
+  "weekStart": ""
+}

assets/dashboards/wordpress-runtime.json

@@ -0,0 +1,987 @@
+{
+  "annotations": {
+    "list": []
+  },
+  "editable": true,
+  "fiscalYearStartMonth": 0,
+  "graphTooltip": 0,
+  "id": null,
+  "links": [],
+  "panels": [
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+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 0
+      },
+      "id": 1,
+      "panels": [],
+      "title": "HTTP Requests",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "smooth",
+            "lineWidth": 2,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "reqps"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 1
+      },
+      "id": 2,
+      "options": {
+        "legend": {
+          "calcs": ["mean", "max"],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(wordpress_http_requests_total[5m])) by (endpoint)",
+          "legendFormat": "{{endpoint}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Requests per Second by Endpoint",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
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+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
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+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "smooth",
+            "lineWidth": 2,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "reqps"
+        },
+        "overrides": [
+          {
+            "matcher": {
+              "id": "byRegexp",
+              "options": "/2..$/"
+            },
+            "properties": [
+              {
+                "id": "color",
+                "value": {
+                  "fixedColor": "green",
+                  "mode": "fixed"
+                }
+              }
+            ]
+          },
+          {
+            "matcher": {
+              "id": "byRegexp",
+              "options": "/4..$/"
+            },
+            "properties": [
+              {
+                "id": "color",
+                "value": {
+                  "fixedColor": "orange",
+                  "mode": "fixed"
+                }
+              }
+            ]
+          },
+          {
+            "matcher": {
+              "id": "byRegexp",
+              "options": "/5..$/"
+            },
+            "properties": [
+              {
+                "id": "color",
+                "value": {
+                  "fixedColor": "red",
+                  "mode": "fixed"
+                }
+              }
+            ]
+          }
+        ]
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 1
+      },
+      "id": 3,
+      "options": {
+        "legend": {
+          "calcs": ["mean", "max"],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(wordpress_http_requests_total[5m])) by (status)",
+          "legendFormat": "{{status}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Requests per Second by Status",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
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+              "tooltip": false,
+              "viz": false
+            }
+          },
+          "mappings": []
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 0,
+        "y": 9
+      },
+      "id": 4,
+      "options": {
+        "legend": {
+          "displayMode": "list",
+          "placement": "right",
+          "showLegend": true
+        },
+        "pieType": "donut",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_http_requests_total) by (method)",
+          "instant": true,
+          "legendFormat": "{{method}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Requests by Method",
+      "type": "piechart"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            }
+          },
+          "mappings": []
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 8,
+        "y": 9
+      },
+      "id": 5,
+      "options": {
+        "legend": {
+          "displayMode": "list",
+          "placement": "right",
+          "showLegend": true
+        },
+        "pieType": "donut",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_http_requests_total) by (endpoint)",
+          "instant": true,
+          "legendFormat": "{{endpoint}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Requests by Endpoint",
+      "type": "piechart"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 8,
+        "x": 16,
+        "y": 9
+      },
+      "id": 6,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_http_requests_total)",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Total Requests (All Time)",
+      "type": "stat"
+    },
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 17
+      },
+      "id": 7,
+      "panels": [],
+      "title": "Request Duration",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "smooth",
+            "lineWidth": 2,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 18
+      },
+      "id": 8,
+      "options": {
+        "legend": {
+          "calcs": ["mean", "max"],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_http_request_duration_seconds_sum / wordpress_http_request_duration_seconds_count",
+          "legendFormat": "{{method}} {{endpoint}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Average Request Duration",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "fillOpacity": 80,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineWidth": 1,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 18
+      },
+      "id": 9,
+      "options": {
+        "barRadius": 0,
+        "barWidth": 0.97,
+        "fullHighlight": false,
+        "groupWidth": 0.7,
+        "legend": {
+          "calcs": [],
+          "displayMode": "list",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "orientation": "horizontal",
+        "showValue": "auto",
+        "stacking": "none",
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        },
+        "xTickLabelRotation": 0,
+        "xTickLabelSpacing": 0
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_http_request_duration_seconds_bucket) by (le)",
+          "format": "table",
+          "instant": true,
+          "legendFormat": "{{le}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Request Duration Distribution (Buckets)",
+      "type": "barchart"
+    },
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 26
+      },
+      "id": 10,
+      "panels": [],
+      "title": "Database Queries",
+      "type": "row"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "smooth",
+            "lineWidth": 2,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 27
+      },
+      "id": 11,
+      "options": {
+        "legend": {
+          "calcs": ["mean", "max"],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "rate(wordpress_db_queries_total[5m])",
+          "legendFormat": "{{endpoint}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Database Queries per Second",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisBorderShow": false,
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "insertNulls": false,
+            "lineInterpolation": "smooth",
+            "lineWidth": 2,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 27
+      },
+      "id": 12,
+      "options": {
+        "legend": {
+          "calcs": ["mean", "max"],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "wordpress_db_query_duration_seconds_sum / wordpress_db_query_duration_seconds_count",
+          "legendFormat": "{{endpoint}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Average Query Duration",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "blue",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 12,
+        "x": 0,
+        "y": 35
+      },
+      "id": 13,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_db_queries_total)",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Total Database Queries (All Time)",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "yellow",
+                "value": 0.1
+              },
+              {
+                "color": "red",
+                "value": 0.5
+              }
+            ]
+          },
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 4,
+        "w": 12,
+        "x": 12,
+        "y": 35
+      },
+      "id": 14,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "expr": "sum(wordpress_db_query_duration_seconds_sum) / sum(wordpress_db_query_duration_seconds_count)",
+          "instant": true,
+          "legendFormat": "__auto",
+          "refId": "A"
+        }
+      ],
+      "title": "Average Query Duration (Overall)",
+      "type": "stat"
+    }
+  ],
+  "refresh": "30s",
+  "schemaVersion": 39,
+  "tags": ["wordpress", "prometheus", "performance"],
+  "templating": {
+    "list": [
+      {
+        "current": {
+          "selected": false,
+          "text": "Prometheus",
+          "value": "Prometheus"
+        },
+        "hide": 0,
+        "includeAll": false,
+        "label": "Data Source",
+        "multi": false,
+        "name": "DS_PROMETHEUS",
+        "options": [],
+        "query": "prometheus",
+        "queryValue": "",
+        "refresh": 1,
+        "regex": "",
+        "skipUrlSync": false,
+        "type": "datasource"
+      }
+    ]
+  },
+  "time": {
+    "from": "now-6h",
+    "to": "now"
+  },
+  "timepicker": {},
+  "timezone": "browser",
+  "title": "WordPress Runtime Performance",
+  "uid": "wp-prometheus-runtime",
+  "version": 1,
+  "weekStart": ""
+}

assets/js/admin.js

@@ -7,7 +7,29 @@
 (function($) {
     'use strict';
 
+    var importFileContent = null;
+
     $(document).ready(function() {
+        // License tab handlers.
+        initLicenseHandlers();
+
+        // Custom metrics tab handlers.
+        initCustomMetricsHandlers();
+
+        // Dashboards tab handlers.
+        initDashboardsHandlers();
+
+        // Runtime metrics reset handler.
+        initResetRuntimeHandler();
+
+        // Storage tab handlers.
+        initStorageHandlers();
+    });
+
+    /**
+     * Initialize license tab handlers.
+     */
+    function initLicenseHandlers() {
         // Validate license button.
         $('#wp-prometheus-validate-license').on('click', function(e) {
             e.preventDefault();
@@ -23,11 +45,171 @@
         // Regenerate token button.
         $('#wp-prometheus-regenerate-token').on('click', function(e) {
             e.preventDefault();
-            if (confirm('Are you sure you want to regenerate the auth token? You will need to update your Prometheus configuration.')) {
+            if (confirm(wpPrometheus.confirmRegenerateToken)) {
                 var newToken = generateToken(32);
                 $('#wp_prometheus_auth_token').val(newToken);
             }
         });
+    }
+
+    /**
+     * Initialize custom metrics tab handlers.
+     */
+    function initCustomMetricsHandlers() {
+        var $formContainer = $('#wp-prometheus-metric-form-container');
+        var $form = $('#wp-prometheus-metric-form');
+        var $showFormBtn = $('#show-metric-form');
+
+        // Show metric form.
+        $showFormBtn.on('click', function() {
+            resetMetricForm();
+            $formContainer.slideDown();
+            $(this).hide();
+        });
+
+        // Cancel metric form.
+        $('#cancel-metric-form').on('click', function() {
+            $formContainer.slideUp();
+            $showFormBtn.show();
+            // Remove edit parameter from URL.
+            if (window.location.search.indexOf('edit=') > -1) {
+                window.history.pushState({}, '', window.location.pathname + '?page=wp-prometheus&tab=custom');
+            }
+        });
+
+        // Value type toggle.
+        $('input[name="value_type"]').on('change', function() {
+            var valueType = $(this).val();
+            if (valueType === 'option') {
+                $('#option-config-row').show();
+                $('#static-values-row').hide();
+            } else {
+                $('#option-config-row').hide();
+                $('#static-values-row').show();
+            }
+        });
+
+        // Add label.
+        $('#add-label').on('click', function() {
+            var $container = $('#metric-labels-container');
+            var labelCount = $container.find('.metric-label-row').length;
+
+            if (labelCount >= 5) {
+                alert('Maximum 5 labels allowed per metric.');
+                return;
+            }
+
+            var $row = $('<div class="metric-label-row">' +
+                '<input type="text" name="labels[]" class="regular-text" placeholder="label_name" pattern="[a-zA-Z_][a-zA-Z0-9_]*">' +
+                '<button type="button" class="button remove-label">&times;</button>' +
+                '</div>');
+            $container.append($row);
+            updateValueRows();
+        });
+
+        // Remove label.
+        $(document).on('click', '.remove-label', function() {
+            $(this).closest('.metric-label-row').remove();
+            updateValueRows();
+        });
+
+        // Add value row.
+        $('#add-value-row').on('click', function() {
+            var $container = $('#metric-values-container');
+            var rowCount = $container.find('.metric-value-row').length;
+            var labelCount = getLabelCount();
+
+            var $row = $('<div class="metric-value-row"></div>');
+
+            // Add label value inputs.
+            var labels = getLabels();
+            for (var i = 0; i < labelCount; i++) {
+                $row.append('<input type="text" name="label_values[' + rowCount + '][]" class="small-text" placeholder="' + (labels[i] || 'value') + '">');
+            }
+
+            // Add metric value input.
+            $row.append('<input type="number" name="label_values[' + rowCount + '][]" class="small-text" step="any" placeholder="Value">');
+            $row.append('<button type="button" class="button remove-value-row">&times;</button>');
+
+            $container.append($row);
+        });
+
+        // Remove value row.
+        $(document).on('click', '.remove-value-row', function() {
+            $(this).closest('.metric-value-row').remove();
+        });
+
+        // Submit metric form.
+        $form.on('submit', function(e) {
+            e.preventDefault();
+            saveCustomMetric();
+        });
+
+        // Delete metric.
+        $(document).on('click', '.delete-metric', function() {
+            var id = $(this).data('id');
+            if (confirm(wpPrometheus.confirmDelete)) {
+                deleteCustomMetric(id);
+            }
+        });
+
+        // Export metrics.
+        $('#export-metrics').on('click', function() {
+            exportMetrics();
+        });
+
+        // Import metrics - trigger file input.
+        $('#import-metrics-btn').on('click', function() {
+            $('#import-metrics-file').click();
+        });
+
+        // Import file selected.
+        $('#import-metrics-file').on('change', function(e) {
+            var file = e.target.files[0];
+            if (file) {
+                var reader = new FileReader();
+                reader.onload = function(e) {
+                    importFileContent = e.target.result;
+                    $('#import-options').slideDown();
+                };
+                reader.readAsText(file);
+            }
+        });
+
+        // Confirm import.
+        $('#confirm-import').on('click', function() {
+            var mode = $('input[name="import_mode"]:checked').val();
+            importMetrics(importFileContent, mode);
+        });
+
+        // Cancel import.
+        $('#cancel-import').on('click', function() {
+            $('#import-options').slideUp();
+            $('#import-metrics-file').val('');
+            importFileContent = null;
+        });
+    }
+
+    /**
+     * Initialize dashboards tab handlers.
+     */
+    function initDashboardsHandlers() {
+        $(document).on('click', '.download-dashboard', function() {
+            var slug = $(this).data('slug');
+            downloadDashboard(slug);
+        });
+    }
+
+    /**
+     * Initialize reset runtime metrics handler.
+     */
+    function initResetRuntimeHandler() {
+        $('#wp-prometheus-reset-runtime').on('click', function() {
+            if (confirm(wpPrometheus.confirmReset)) {
+                resetRuntimeMetrics();
+            }
+        });
+    }
 
     /**
      * Perform a license action via AJAX.
@@ -82,6 +264,325 @@
         });
     }
 
+    /**
+     * Save custom metric via AJAX.
+     */
+    function saveCustomMetric() {
+        var $spinner = $('#wp-prometheus-metric-spinner');
+        var $message = $('#wp-prometheus-metric-message');
+        var $form = $('#wp-prometheus-metric-form');
+
+        $spinner.addClass('is-active');
+        $message.hide();
+
+        var formData = $form.serialize();
+        formData += '&action=wp_prometheus_save_custom_metric';
+        formData += '&nonce=' + wpPrometheus.customMetricNonce;
+
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: formData,
+            success: function(response) {
+                $spinner.removeClass('is-active');
+
+                if (response.success) {
+                    $message
+                        .removeClass('notice-error')
+                        .addClass('notice notice-success')
+                        .html('<p>' + response.data.message + '</p>')
+                        .show();
+
+                    setTimeout(function() {
+                        window.location.href = window.location.pathname + '?page=wp-prometheus&tab=custom';
+                    }, 1000);
+                } else {
+                    $message
+                        .removeClass('notice-success')
+                        .addClass('notice notice-error')
+                        .html('<p>' + (response.data.message || 'An error occurred.') + '</p>')
+                        .show();
+                }
+            },
+            error: function() {
+                $spinner.removeClass('is-active');
+                $message
+                    .removeClass('notice-success')
+                    .addClass('notice notice-error')
+                    .html('<p>Connection error. Please try again.</p>')
+                    .show();
+            }
+        });
+    }
+
+    /**
+     * Delete custom metric via AJAX.
+     *
+     * @param {string} id Metric ID.
+     */
+    function deleteCustomMetric(id) {
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: {
+                action: 'wp_prometheus_delete_custom_metric',
+                nonce: wpPrometheus.customMetricNonce,
+                id: id
+            },
+            success: function(response) {
+                if (response.success) {
+                    $('tr[data-metric-id="' + id + '"]').fadeOut(function() {
+                        $(this).remove();
+                        // Check if table is empty.
+                        if ($('.wp-prometheus-custom-metrics tbody tr').length === 0) {
+                            location.reload();
+                        }
+                    });
+                } else {
+                    alert(response.data.message || 'An error occurred.');
+                }
+            },
+            error: function() {
+                alert('Connection error. Please try again.');
+            }
+        });
+    }
+
+    /**
+     * Export metrics via AJAX.
+     */
+    function exportMetrics() {
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: {
+                action: 'wp_prometheus_export_metrics',
+                nonce: wpPrometheus.exportNonce
+            },
+            success: function(response) {
+                if (response.success) {
+                    downloadFile(response.data.json, response.data.filename, 'application/json');
+                } else {
+                    alert(response.data.message || 'An error occurred.');
+                }
+            },
+            error: function() {
+                alert('Connection error. Please try again.');
+            }
+        });
+    }
+
+    /**
+     * Import metrics via AJAX.
+     *
+     * @param {string} json JSON content.
+     * @param {string} mode Import mode.
+     */
+    function importMetrics(json, mode) {
+        var $spinner = $('#wp-prometheus-import-spinner');
+        var $message = $('#wp-prometheus-import-message');
+
+        $spinner.addClass('is-active');
+        $message.hide();
+
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: {
+                action: 'wp_prometheus_import_metrics',
+                nonce: wpPrometheus.importNonce,
+                json: json,
+                mode: mode
+            },
+            success: function(response) {
+                $spinner.removeClass('is-active');
+
+                if (response.success) {
+                    $message
+                        .removeClass('notice-error')
+                        .addClass('notice notice-success')
+                        .html('<p>' + response.data.message + '</p>')
+                        .show();
+
+                    $('#import-options').slideUp();
+                    $('#import-metrics-file').val('');
+                    importFileContent = null;
+
+                    setTimeout(function() {
+                        location.reload();
+                    }, 1500);
+                } else {
+                    $message
+                        .removeClass('notice-success')
+                        .addClass('notice notice-error')
+                        .html('<p>' + (response.data.message || 'An error occurred.') + '</p>')
+                        .show();
+                }
+            },
+            error: function() {
+                $spinner.removeClass('is-active');
+                $message
+                    .removeClass('notice-success')
+                    .addClass('notice notice-error')
+                    .html('<p>Connection error. Please try again.</p>')
+                    .show();
+            }
+        });
+    }
+
+    /**
+     * Download dashboard via AJAX.
+     *
+     * @param {string} slug Dashboard slug.
+     */
+    function downloadDashboard(slug) {
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: {
+                action: 'wp_prometheus_download_dashboard',
+                nonce: wpPrometheus.dashboardNonce,
+                slug: slug
+            },
+            success: function(response) {
+                if (response.success) {
+                    downloadFile(response.data.json, response.data.filename, 'application/json');
+                } else {
+                    alert(response.data.message || 'An error occurred.');
+                }
+            },
+            error: function() {
+                alert('Connection error. Please try again.');
+            }
+        });
+    }
+
+    /**
+     * Reset runtime metrics via AJAX.
+     */
+    function resetRuntimeMetrics() {
+        var $spinner = $('#wp-prometheus-reset-spinner');
+        var $message = $('#wp-prometheus-reset-message');
+
+        $spinner.addClass('is-active');
+        $message.hide();
+
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: {
+                action: 'wp_prometheus_reset_runtime_metrics',
+                nonce: wpPrometheus.resetRuntimeNonce
+            },
+            success: function(response) {
+                $spinner.removeClass('is-active');
+
+                if (response.success) {
+                    $message
+                        .removeClass('notice-error')
+                        .addClass('notice notice-success')
+                        .html('<p>' + response.data.message + '</p>')
+                        .show();
+                } else {
+                    $message
+                        .removeClass('notice-success')
+                        .addClass('notice notice-error')
+                        .html('<p>' + (response.data.message || 'An error occurred.') + '</p>')
+                        .show();
+                }
+            },
+            error: function() {
+                $spinner.removeClass('is-active');
+                $message
+                    .removeClass('notice-success')
+                    .addClass('notice notice-error')
+                    .html('<p>Connection error. Please try again.</p>')
+                    .show();
+            }
+        });
+    }
+
+    /**
+     * Reset the metric form to default state.
+     */
+    function resetMetricForm() {
+        var $form = $('#wp-prometheus-metric-form');
+        $form[0].reset();
+        $('#metric-id').val('');
+        $('#wp-prometheus-form-title').text('Add New Metric');
+        $('#option-config-row').hide();
+        $('#static-values-row').show();
+        $('#wp-prometheus-metric-message').hide();
+
+        // Reset labels to single empty row.
+        $('#metric-labels-container').html(
+            '<div class="metric-label-row">' +
+            '<input type="text" name="labels[]" class="regular-text" placeholder="label_name" pattern="[a-zA-Z_][a-zA-Z0-9_]*">' +
+            '<button type="button" class="button remove-label">&times;</button>' +
+            '</div>'
+        );
+
+        // Reset values to single empty row.
+        $('#metric-values-container').html(
+            '<div class="metric-value-row">' +
+            '<input type="number" name="label_values[0][]" class="small-text" step="any" placeholder="Value">' +
+            '<button type="button" class="button remove-value-row">&times;</button>' +
+            '</div>'
+        );
+    }
+
+    /**
+     * Update value rows when labels change.
+     */
+    function updateValueRows() {
+        var labels = getLabels();
+        var labelCount = labels.length;
+
+        $('#metric-values-container .metric-value-row').each(function(rowIndex) {
+            var $row = $(this);
+            var inputs = $row.find('input').toArray();
+            var currentValues = inputs.map(function(input) { return input.value; });
+
+            // Remove all inputs except the value and button.
+            $row.find('input').remove();
+
+            // Re-add label inputs.
+            for (var i = 0; i < labelCount; i++) {
+                var val = currentValues[i] || '';
+                $row.prepend('<input type="text" name="label_values[' + rowIndex + '][]" class="small-text" placeholder="' + (labels[i] || 'value') + '" value="' + val + '">');
+            }
+
+            // Re-add value input.
+            var metricVal = currentValues[currentValues.length - 1] || '';
+            $row.find('.remove-value-row').before('<input type="number" name="label_values[' + rowIndex + '][]" class="small-text" step="any" placeholder="Value" value="' + metricVal + '">');
+        });
+    }
+
+    /**
+     * Get current label names.
+     *
+     * @return {string[]} Array of label names.
+     */
+    function getLabels() {
+        var labels = [];
+        $('#metric-labels-container input[name="labels[]"]').each(function() {
+            var val = $(this).val().trim();
+            if (val) {
+                labels.push(val);
+            }
+        });
+        return labels;
+    }
+
+    /**
+     * Get current label count.
+     *
+     * @return {number} Number of labels.
+     */
+    function getLabelCount() {
+        return getLabels().length;
+    }
+
     /**
      * Generate a random token.
      *
@@ -96,5 +597,150 @@
         }
         return token;
     }
+
+    /**
+     * Download a file.
+     *
+     * @param {string} content File content.
+     * @param {string} filename Filename.
+     * @param {string} type MIME type.
+     */
+    function downloadFile(content, filename, type) {
+        var blob = new Blob([content], { type: type });
+        var url = URL.createObjectURL(blob);
+        var a = document.createElement('a');
+        a.href = url;
+        a.download = filename;
+        document.body.appendChild(a);
+        a.click();
+        document.body.removeChild(a);
+        URL.revokeObjectURL(url);
+    }
+
+    /**
+     * Initialize storage tab handlers.
+     */
+    function initStorageHandlers() {
+        var $form = $('#wp-prometheus-storage-form');
+        var $adapterSelect = $('#storage-adapter');
+
+        // Show/hide adapter-specific config.
+        $adapterSelect.on('change', function() {
+            var adapter = $(this).val();
+            $('#redis-config').toggle(adapter === 'redis');
+            $('#apcu-config').toggle(adapter === 'apcu');
         });
+
+        // Save storage settings.
+        $form.on('submit', function(e) {
+            e.preventDefault();
+            saveStorageSettings();
+        });
+
+        // Test storage connection.
+        $('#test-storage').on('click', function() {
+            testStorageConnection();
+        });
+    }
+
+    /**
+     * Save storage settings via AJAX.
+     */
+    function saveStorageSettings() {
+        var $spinner = $('#wp-prometheus-storage-spinner');
+        var $message = $('#wp-prometheus-storage-message');
+        var $form = $('#wp-prometheus-storage-form');
+
+        $spinner.addClass('is-active');
+        $message.hide();
+
+        var formData = $form.serialize();
+        formData += '&action=wp_prometheus_save_storage';
+        formData += '&nonce=' + wpPrometheus.storageNonce;
+
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: formData,
+            success: function(response) {
+                $spinner.removeClass('is-active');
+
+                if (response.success) {
+                    var noticeClass = response.data.warning ? 'notice-warning' : 'notice-success';
+                    $message
+                        .removeClass('notice-error notice-success notice-warning')
+                        .addClass('notice ' + noticeClass)
+                        .html('<p>' + response.data.message + '</p>')
+                        .show();
+
+                    if (!response.data.warning) {
+                        setTimeout(function() {
+                            location.reload();
+                        }, 1500);
+                    }
+                } else {
+                    $message
+                        .removeClass('notice-success notice-warning')
+                        .addClass('notice notice-error')
+                        .html('<p>' + (response.data.message || 'An error occurred.') + '</p>')
+                        .show();
+                }
+            },
+            error: function() {
+                $spinner.removeClass('is-active');
+                $message
+                    .removeClass('notice-success notice-warning')
+                    .addClass('notice notice-error')
+                    .html('<p>Connection error. Please try again.</p>')
+                    .show();
+            }
+        });
+    }
+
+    /**
+     * Test storage connection via AJAX.
+     */
+    function testStorageConnection() {
+        var $spinner = $('#wp-prometheus-storage-spinner');
+        var $message = $('#wp-prometheus-storage-message');
+        var $form = $('#wp-prometheus-storage-form');
+
+        $spinner.addClass('is-active');
+        $message.hide();
+
+        var formData = $form.serialize();
+        formData += '&action=wp_prometheus_test_storage';
+        formData += '&nonce=' + wpPrometheus.storageNonce;
+
+        $.ajax({
+            url: wpPrometheus.ajaxUrl,
+            type: 'POST',
+            data: formData,
+            success: function(response) {
+                $spinner.removeClass('is-active');
+
+                if (response.success) {
+                    $message
+                        .removeClass('notice-error notice-warning')
+                        .addClass('notice notice-success')
+                        .html('<p>' + response.data.message + '</p>')
+                        .show();
+                } else {
+                    $message
+                        .removeClass('notice-success notice-warning')
+                        .addClass('notice notice-error')
+                        .html('<p>' + (response.data.message || 'Connection test failed.') + '</p>')
+                        .show();
+                }
+            },
+            error: function() {
+                $spinner.removeClass('is-active');
+                $message
+                    .removeClass('notice-success notice-warning')
+                    .addClass('notice notice-error')
+                    .html('<p>Connection error. Please try again.</p>')
+                    .show();
+            }
+        });
+    }
 })(jQuery);

languages/wp-prometheus-de_CH.po

@@ -3,7 +3,7 @@
 # This file is distributed under the GPL v2 or later.
 msgid ""
 msgstr ""
-"Project-Id-Version: WP Prometheus 0.2.0\n"
+"Project-Id-Version: WP Prometheus 0.4.0\n"
 "Report-Msgid-Bugs-To: https://src.bundespruefstelle.ch/magdev/wp-prometheus/issues\n"
 "POT-Creation-Date: 2026-02-02T00:00:00+00:00\n"
 "PO-Revision-Date: 2026-02-02T00:00:00+00:00\n"
@@ -31,6 +31,14 @@ msgstr "Lizenz"
 msgid "Help"
 msgstr "Hilfe"
 
+#: src/Admin/Settings.php
+msgid "Custom Metrics"
+msgstr "Eigene Metriken"
+
+#: src/Admin/Settings.php
+msgid "Dashboards"
+msgstr "Dashboards"
+
 #: src/Admin/Settings.php
 msgid "License settings saved."
 msgstr "Lizenz-Einstellungen gespeichert."
@@ -213,6 +221,18 @@ msgstr "WooCommerce-Umsatz (gesamt, heute, Monat)"
 msgid "WooCommerce Customers (registered, guest)"
 msgstr "WooCommerce-Kunden (registriert, Gast)"
 
+#: src/Admin/Settings.php
+msgid "Reset Runtime Metrics"
+msgstr "Laufzeit-Metriken zuruecksetzen"
+
+#: src/Admin/Settings.php
+msgid "Clear all accumulated runtime metric data."
+msgstr "Alle gesammelten Laufzeit-Metrikdaten loeschen."
+
+#: src/Admin/Settings.php
+msgid "Reset Metrics"
+msgstr "Metriken zuruecksetzen"
+
 #: src/Admin/Settings.php
 msgid "Prometheus Configuration"
 msgstr "Prometheus-Konfiguration"
@@ -329,14 +349,252 @@ msgstr "WooCommerce-Umsatz nach Zeitraum"
 msgid "WooCommerce customers by type"
 msgstr "WooCommerce-Kunden nach Typ"
 
-#: src/Admin/Settings.php
-msgid "Custom Metrics"
-msgstr "Benutzerdefinierte Metriken"
-
 #: src/Admin/Settings.php
 msgid "You can add custom metrics using the wp_prometheus_collect_metrics action:"
 msgstr "Sie koennen benutzerdefinierte Metriken mit der wp_prometheus_collect_metrics-Aktion hinzufuegen:"
 
+#: src/Admin/Settings.php
+msgid "Add Custom Metric"
+msgstr "Eigene Metrik hinzufuegen"
+
+#: src/Admin/Settings.php
+msgid "Edit Custom Metric"
+msgstr "Eigene Metrik bearbeiten"
+
+#: src/Admin/Settings.php
+msgid "Metric Name"
+msgstr "Metrik-Name"
+
+#: src/Admin/Settings.php
+msgid "Must follow Prometheus naming conventions."
+msgstr "Muss den Prometheus-Namenskonventionen entsprechen."
+
+#: src/Admin/Settings.php
+msgid "Help Text"
+msgstr "Hilfetext"
+
+#: src/Admin/Settings.php
+msgid "Description shown in Prometheus output."
+msgstr "Beschreibung in der Prometheus-Ausgabe."
+
+#: src/Admin/Settings.php
+msgid "Value Type"
+msgstr "Werttyp"
+
+#: src/Admin/Settings.php
+msgid "Static Value"
+msgstr "Statischer Wert"
+
+#: src/Admin/Settings.php
+msgid "WordPress Option"
+msgstr "WordPress-Option"
+
+#: src/Admin/Settings.php
+msgid "Static Value:"
+msgstr "Statischer Wert:"
+
+#: src/Admin/Settings.php
+msgid "Option Name:"
+msgstr "Optionsname:"
+
+#: src/Admin/Settings.php
+msgid "The name of the WordPress option to read."
+msgstr "Der Name der zu lesenden WordPress-Option."
+
+#: src/Admin/Settings.php
+msgid "Labels"
+msgstr "Labels"
+
+#: src/Admin/Settings.php
+msgid "Label name"
+msgstr "Label-Name"
+
+#: src/Admin/Settings.php
+msgid "Add Label"
+msgstr "Label hinzufuegen"
+
+#: src/Admin/Settings.php
+msgid "Label Values"
+msgstr "Label-Werte"
+
+#: src/Admin/Settings.php
+msgid "Value"
+msgstr "Wert"
+
+#: src/Admin/Settings.php
+msgid "Add Value Row"
+msgstr "Wertezeile hinzufuegen"
+
+#: src/Admin/Settings.php
+msgid "Enabled"
+msgstr "Aktiviert"
+
+#: src/Admin/Settings.php
+msgid "Save Metric"
+msgstr "Metrik speichern"
+
+#: src/Admin/Settings.php
+msgid "Cancel"
+msgstr "Abbrechen"
+
+#: src/Admin/Settings.php
+msgid "Your Custom Metrics"
+msgstr "Ihre eigenen Metriken"
+
+#: src/Admin/Settings.php
+msgid "Name"
+msgstr "Name"
+
+#: src/Admin/Settings.php
+msgid "Status"
+msgstr "Status"
+
+#: src/Admin/Settings.php
+msgid "Actions"
+msgstr "Aktionen"
+
+#: src/Admin/Settings.php
+msgid "Active"
+msgstr "Aktiv"
+
+#: src/Admin/Settings.php
+msgid "Inactive"
+msgstr "Inaktiv"
+
+#: src/Admin/Settings.php
+msgid "Edit"
+msgstr "Bearbeiten"
+
+#: src/Admin/Settings.php
+msgid "Delete"
+msgstr "Loeschen"
+
+#: src/Admin/Settings.php
+msgid "No custom metrics defined yet."
+msgstr "Noch keine eigenen Metriken definiert."
+
+#: src/Admin/Settings.php
+msgid "Export / Import"
+msgstr "Export / Import"
+
+#: src/Admin/Settings.php
+msgid "Export your custom metrics configuration for backup or transfer to another site."
+msgstr "Exportieren Sie Ihre Metriken-Konfiguration zur Sicherung oder Uebertragung auf eine andere Website."
+
+#: src/Admin/Settings.php
+msgid "Export Metrics"
+msgstr "Metriken exportieren"
+
+#: src/Admin/Settings.php
+msgid "Import Metrics"
+msgstr "Metriken importieren"
+
+#: src/Admin/Settings.php
+msgid "Import Options"
+msgstr "Import-Optionen"
+
+#: src/Admin/Settings.php
+msgid "Skip existing metrics"
+msgstr "Bestehende Metriken ueberspringen"
+
+#: src/Admin/Settings.php
+msgid "Overwrite existing metrics"
+msgstr "Bestehende Metriken ueberschreiben"
+
+#: src/Admin/Settings.php
+msgid "Rename duplicates"
+msgstr "Duplikate umbenennen"
+
+#: src/Admin/Settings.php
+msgid "Import"
+msgstr "Importieren"
+
+#: src/Admin/Settings.php
+msgid "Grafana Dashboard Templates"
+msgstr "Grafana Dashboard-Vorlagen"
+
+#: src/Admin/Settings.php
+msgid "Download pre-built Grafana dashboards for visualizing your WordPress metrics."
+msgstr "Laden Sie vorgefertigte Grafana-Dashboards zur Visualisierung Ihrer WordPress-Metriken herunter."
+
+#: src/Admin/Settings.php
+msgid "Download"
+msgstr "Herunterladen"
+
+#: src/Admin/Settings.php
+msgid "Import instructions:"
+msgstr "Import-Anleitung:"
+
+#: src/Admin/Settings.php
+msgid "Download the desired dashboard JSON file"
+msgstr "Laden Sie die gewuenschte Dashboard-JSON-Datei herunter"
+
+#: src/Admin/Settings.php
+msgid "In Grafana, go to Dashboards > Import"
+msgstr "Gehen Sie in Grafana zu Dashboards > Import"
+
+#: src/Admin/Settings.php
+msgid "Upload the JSON file or paste its contents"
+msgstr "Laden Sie die JSON-Datei hoch oder fuegen Sie deren Inhalt ein"
+
+#: src/Admin/Settings.php
+msgid "Select your Prometheus data source"
+msgstr "Waehlen Sie Ihre Prometheus-Datenquelle"
+
+#: src/Admin/Settings.php
+msgid "Click Import"
+msgstr "Klicken Sie auf Import"
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Metric name is required."
+msgstr "Metrik-Name ist erforderlich."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid metric name format."
+msgstr "Ungueltiges Metrik-Namensformat."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "A metric with this name already exists."
+msgstr "Eine Metrik mit diesem Namen existiert bereits."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Help text is required."
+msgstr "Hilfetext ist erforderlich."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid value type."
+msgstr "Ungueltiger Werttyp."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Static value must be numeric."
+msgstr "Statischer Wert muss numerisch sein."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Option name is required for option value type."
+msgstr "Optionsname ist fuer den Options-Werttyp erforderlich."
+
+#. translators: %d: Maximum number of labels
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Maximum %d labels allowed."
+msgstr "Maximal %d Labels erlaubt."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid label name format."
+msgstr "Ungueltiges Label-Namensformat."
+
+#. translators: %d: Maximum number of label value combinations
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Maximum %d label value combinations allowed."
+msgstr "Maximal %d Label-Wert-Kombinationen erlaubt."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid JSON format."
+msgstr "Ungueltiges JSON-Format."
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid export format."
+msgstr "Ungueltiges Export-Format."
+
 #: src/Plugin.php
 msgid "Settings"
 msgstr "Einstellungen"
@@ -359,3 +617,265 @@ msgstr "WP Prometheus erfordert installierte Composer-Abhaengigkeiten. Bitte fue
 #: wp-prometheus.php
 msgid "WP Prometheus requires PHP version %s or higher."
 msgstr "WP Prometheus erfordert PHP-Version %s oder hoeher."
+
+#: src/Admin/Settings.php
+msgid "Storage"
+msgstr "Speicher"
+
+#: src/Admin/Settings.php
+msgid "Metrics Storage Configuration"
+msgstr "Metriken-Speicherkonfiguration"
+
+#: src/Admin/Settings.php
+msgid "Configure how Prometheus metrics are stored. Persistent storage (Redis, APCu) allows metrics to survive between requests and aggregate data over time."
+msgstr "Konfigurieren Sie, wie Prometheus-Metriken gespeichert werden. Persistenter Speicher (Redis, APCu) ermoeglicht es, Metriken zwischen Anfragen zu erhalten und Daten ueber Zeit zu aggregieren."
+
+#: src/Admin/Settings.php
+msgid "Environment Override Active"
+msgstr "Umgebungsvariablen-Ueberschreibung aktiv"
+
+#: src/Admin/Settings.php
+msgid "Storage adapter is configured via environment variable. Admin settings will be ignored."
+msgstr "Speicher-Adapter ist ueber Umgebungsvariable konfiguriert. Admin-Einstellungen werden ignoriert."
+
+#: src/Admin/Settings.php
+msgid "Storage Fallback Active"
+msgstr "Speicher-Fallback aktiv"
+
+#: src/Admin/Settings.php
+msgid "Falling back to In-Memory storage."
+msgstr "Faellt zurueck auf In-Memory-Speicher."
+
+#: src/Admin/Settings.php
+msgid "Current Status:"
+msgstr "Aktueller Status:"
+
+#. translators: %s: Active adapter name
+#: src/Admin/Settings.php
+msgid "Using %s storage."
+msgstr "Verwende %s-Speicher."
+
+#: src/Admin/Settings.php
+msgid "Storage Adapter"
+msgstr "Speicher-Adapter"
+
+#: src/Admin/Settings.php
+msgid "unavailable"
+msgstr "nicht verfuegbar"
+
+#: src/Admin/Settings.php
+msgid "Select the storage backend for metrics. Redis and APCu require their respective PHP extensions."
+msgstr "Waehlen Sie das Speicher-Backend fuer Metriken. Redis und APCu erfordern ihre jeweiligen PHP-Erweiterungen."
+
+#: src/Admin/Settings.php
+msgid "Redis Configuration"
+msgstr "Redis-Konfiguration"
+
+#: src/Admin/Settings.php
+msgid "Host"
+msgstr "Host"
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Can be overridden with %s environment variable."
+msgstr "Kann mit Umgebungsvariable %s ueberschrieben werden."
+
+#: src/Admin/Settings.php
+msgid "Port"
+msgstr "Port"
+
+#: src/Admin/Settings.php
+msgid "Password"
+msgstr "Passwort"
+
+#: src/Admin/Settings.php
+msgid "Leave empty if not required"
+msgstr "Leer lassen, falls nicht erforderlich"
+
+#: src/Admin/Settings.php
+msgid "Database"
+msgstr "Datenbank"
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Redis database index (0-15). Can be overridden with %s."
+msgstr "Redis-Datenbankindex (0-15). Kann mit %s ueberschrieben werden."
+
+#: src/Admin/Settings.php
+msgid "Key Prefix"
+msgstr "Schluessel-Praefix"
+
+#: src/Admin/Settings.php
+msgid "Prefix for Redis keys. Useful when sharing Redis with other applications."
+msgstr "Praefix fuer Redis-Schluessel. Nuetzlich bei gemeinsamer Redis-Nutzung mit anderen Anwendungen."
+
+#: src/Admin/Settings.php
+msgid "APCu Configuration"
+msgstr "APCu-Konfiguration"
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Prefix for APCu keys. Can be overridden with %s."
+msgstr "Praefix fuer APCu-Schluessel. Kann mit %s ueberschrieben werden."
+
+#: src/Admin/Settings.php
+msgid "Save Storage Settings"
+msgstr "Speicher-Einstellungen speichern"
+
+#: src/Admin/Settings.php
+msgid "Test Connection"
+msgstr "Verbindung testen"
+
+#: src/Admin/Settings.php
+msgid "Environment Variables"
+msgstr "Umgebungsvariablen"
+
+#: src/Admin/Settings.php
+msgid "For Docker or containerized environments, you can configure storage using environment variables. These take precedence over admin settings."
+msgstr "Fuer Docker- oder Container-Umgebungen koennen Sie den Speicher ueber Umgebungsvariablen konfigurieren. Diese haben Vorrang vor Admin-Einstellungen."
+
+#: src/Admin/Settings.php
+msgid "Variable"
+msgstr "Variable"
+
+#: src/Admin/Settings.php
+msgid "Example"
+msgstr "Beispiel"
+
+#: src/Admin/Settings.php
+msgid "Storage adapter to use"
+msgstr "Zu verwendender Speicher-Adapter"
+
+#: src/Admin/Settings.php
+msgid "Redis server hostname"
+msgstr "Redis-Server-Hostname"
+
+#: src/Admin/Settings.php
+msgid "Redis server port"
+msgstr "Redis-Server-Port"
+
+#: src/Admin/Settings.php
+msgid "Redis authentication password"
+msgstr "Redis-Authentifizierungspasswort"
+
+#: src/Admin/Settings.php
+msgid "Redis database index"
+msgstr "Redis-Datenbankindex"
+
+#: src/Admin/Settings.php
+msgid "Redis key prefix"
+msgstr "Redis-Schluessel-Praefix"
+
+#: src/Admin/Settings.php
+msgid "APCu key prefix"
+msgstr "APCu-Schluessel-Praefix"
+
+#: src/Admin/Settings.php
+msgid "Docker Compose Example"
+msgstr "Docker Compose-Beispiel"
+
+#: src/Admin/Settings.php
+msgid "Permission denied."
+msgstr "Zugriff verweigert."
+
+#: src/Admin/Settings.php
+msgid "Storage adapter is configured via environment variable and cannot be changed."
+msgstr "Speicher-Adapter ist ueber Umgebungsvariable konfiguriert und kann nicht geaendert werden."
+
+#: src/Admin/Settings.php
+msgid "Invalid storage adapter."
+msgstr "Ungueltiger Speicher-Adapter."
+
+#: src/Admin/Settings.php
+msgid "Storage settings saved successfully."
+msgstr "Speicher-Einstellungen erfolgreich gespeichert."
+
+#: src/Admin/Settings.php
+msgid "Storage settings saved, but connection test failed:"
+msgstr "Speicher-Einstellungen gespeichert, aber Verbindungstest fehlgeschlagen:"
+
+#: src/Metrics/StorageFactory.php
+msgid "In-Memory (default, no persistence)"
+msgstr "In-Memory (Standard, keine Persistenz)"
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis (requires PHP Redis extension)"
+msgstr "Redis (erfordert PHP-Redis-Erweiterung)"
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu (requires APCu extension)"
+msgstr "APCu (erfordert APCu-Erweiterung)"
+
+#: src/Metrics/StorageFactory.php
+msgid "PHP Redis extension is not installed."
+msgstr "PHP-Redis-Erweiterung ist nicht installiert."
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Redis connection failed: %s"
+msgstr "Redis-Verbindung fehlgeschlagen: %s"
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Redis error: %s"
+msgstr "Redis-Fehler: %s"
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Storage error: %s"
+msgstr "Speicherfehler: %s"
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu extension is not installed."
+msgstr "APCu-Erweiterung ist nicht installiert."
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu is installed but not enabled."
+msgstr "APCu ist installiert, aber nicht aktiviert."
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "APCu error: %s"
+msgstr "APCu-Fehler: %s"
+
+#: src/Metrics/StorageFactory.php
+msgid "In-Memory storage is always available."
+msgstr "In-Memory-Speicher ist immer verfuegbar."
+
+#: src/Metrics/StorageFactory.php
+msgid "Unknown storage adapter."
+msgstr "Unbekannter Speicher-Adapter."
+
+#: src/Metrics/StorageFactory.php
+msgid "Could not connect to Redis server."
+msgstr "Verbindung zum Redis-Server konnte nicht hergestellt werden."
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis authentication failed."
+msgstr "Redis-Authentifizierung fehlgeschlagen."
+
+#. translators: %s: Redis host:port
+#: src/Metrics/StorageFactory.php
+msgid "Successfully connected to Redis at %s."
+msgstr "Erfolgreich mit Redis verbunden unter %s."
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis ping failed."
+msgstr "Redis-Ping fehlgeschlagen."
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu is installed but not enabled. Check your php.ini settings."
+msgstr "APCu ist installiert, aber nicht aktiviert. Pruefen Sie Ihre php.ini-Einstellungen."
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu store operation failed."
+msgstr "APCu-Speicheroperation fehlgeschlagen."
+
+#. translators: %s: Memory info
+#: src/Metrics/StorageFactory.php
+msgid "APCu is working. Memory: %s used."
+msgstr "APCu funktioniert. Speicher: %s belegt."
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu fetch operation returned unexpected value."
+msgstr "APCu-Abrufoperation hat unerwarteten Wert zurueckgegeben."

languages/wp-prometheus.pot

@@ -2,7 +2,7 @@
 # This file is distributed under the GPL v2 or later.
 msgid ""
 msgstr ""
-"Project-Id-Version: WP Prometheus 0.2.0\n"
+"Project-Id-Version: WP Prometheus 0.4.0\n"
 "Report-Msgid-Bugs-To: https://src.bundespruefstelle.ch/magdev/wp-prometheus/issues\n"
 "POT-Creation-Date: 2026-02-02T00:00:00+00:00\n"
 "MIME-Version: 1.0\n"
@@ -28,6 +28,14 @@ msgstr ""
 msgid "Help"
 msgstr ""
 
+#: src/Admin/Settings.php
+msgid "Custom Metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Dashboards"
+msgstr ""
+
 #: src/Admin/Settings.php
 msgid "License settings saved."
 msgstr ""
@@ -210,6 +218,18 @@ msgstr ""
 msgid "WooCommerce Customers (registered, guest)"
 msgstr ""
 
+#: src/Admin/Settings.php
+msgid "Reset Runtime Metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Clear all accumulated runtime metric data."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Reset Metrics"
+msgstr ""
+
 #: src/Admin/Settings.php
 msgid "Prometheus Configuration"
 msgstr ""
@@ -327,11 +347,249 @@ msgid "WooCommerce customers by type"
 msgstr ""
 
 #: src/Admin/Settings.php
-msgid "Custom Metrics"
+msgid "You can add custom metrics using the wp_prometheus_collect_metrics action:"
 msgstr ""
 
 #: src/Admin/Settings.php
-msgid "You can add custom metrics using the wp_prometheus_collect_metrics action:"
+msgid "Add Custom Metric"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Edit Custom Metric"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Metric Name"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Must follow Prometheus naming conventions."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Help Text"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Description shown in Prometheus output."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Value Type"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Static Value"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "WordPress Option"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Static Value:"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Option Name:"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "The name of the WordPress option to read."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Labels"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Label name"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Add Label"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Label Values"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Value"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Add Value Row"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Enabled"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Save Metric"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Cancel"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Your Custom Metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Name"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Status"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Actions"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Active"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Inactive"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Edit"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Delete"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "No custom metrics defined yet."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Export / Import"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Export your custom metrics configuration for backup or transfer to another site."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Export Metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Import Metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Import Options"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Skip existing metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Overwrite existing metrics"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Rename duplicates"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Import"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Grafana Dashboard Templates"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Download pre-built Grafana dashboards for visualizing your WordPress metrics."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Download"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Import instructions:"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Download the desired dashboard JSON file"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "In Grafana, go to Dashboards > Import"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Upload the JSON file or paste its contents"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Select your Prometheus data source"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Click Import"
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Metric name is required."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid metric name format."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "A metric with this name already exists."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Help text is required."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid value type."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Static value must be numeric."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Option name is required for option value type."
+msgstr ""
+
+#. translators: %d: Maximum number of labels
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Maximum %d labels allowed."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid label name format."
+msgstr ""
+
+#. translators: %d: Maximum number of label value combinations
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Maximum %d label value combinations allowed."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid JSON format."
+msgstr ""
+
+#: src/Metrics/CustomMetricBuilder.php
+msgid "Invalid export format."
 msgstr ""
 
 #: src/Plugin.php
@@ -356,3 +614,265 @@ msgstr ""
 #: wp-prometheus.php
 msgid "WP Prometheus requires PHP version %s or higher."
 msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Metrics Storage Configuration"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Configure how Prometheus metrics are stored. Persistent storage (Redis, APCu) allows metrics to survive between requests and aggregate data over time."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Environment Override Active"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage adapter is configured via environment variable. Admin settings will be ignored."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage Fallback Active"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Falling back to In-Memory storage."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Current Status:"
+msgstr ""
+
+#. translators: %s: Active adapter name
+#: src/Admin/Settings.php
+msgid "Using %s storage."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage Adapter"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "unavailable"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Select the storage backend for metrics. Redis and APCu require their respective PHP extensions."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis Configuration"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Host"
+msgstr ""
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Can be overridden with %s environment variable."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Port"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Password"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Leave empty if not required"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Database"
+msgstr ""
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Redis database index (0-15). Can be overridden with %s."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Key Prefix"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Prefix for Redis keys. Useful when sharing Redis with other applications."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "APCu Configuration"
+msgstr ""
+
+#. translators: %s: Environment variable name
+#: src/Admin/Settings.php
+msgid "Prefix for APCu keys. Can be overridden with %s."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Save Storage Settings"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Test Connection"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Environment Variables"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "For Docker or containerized environments, you can configure storage using environment variables. These take precedence over admin settings."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Variable"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Example"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage adapter to use"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis server hostname"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis server port"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis authentication password"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis database index"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Redis key prefix"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "APCu key prefix"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Docker Compose Example"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Permission denied."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage adapter is configured via environment variable and cannot be changed."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Invalid storage adapter."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage settings saved successfully."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Storage settings saved, but connection test failed:"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "In-Memory (default, no persistence)"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis (requires PHP Redis extension)"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu (requires APCu extension)"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "PHP Redis extension is not installed."
+msgstr ""
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Redis connection failed: %s"
+msgstr ""
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Redis error: %s"
+msgstr ""
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "Storage error: %s"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu extension is not installed."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu is installed but not enabled."
+msgstr ""
+
+#. translators: %s: Error message
+#: src/Metrics/StorageFactory.php
+msgid "APCu error: %s"
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "In-Memory storage is always available."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "Unknown storage adapter."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "Could not connect to Redis server."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis authentication failed."
+msgstr ""
+
+#. translators: %s: Redis host:port
+#: src/Metrics/StorageFactory.php
+msgid "Successfully connected to Redis at %s."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "Redis ping failed."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu is installed but not enabled. Check your php.ini settings."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu store operation failed."
+msgstr ""
+
+#. translators: %s: Memory info
+#: src/Metrics/StorageFactory.php
+msgid "APCu is working. Memory: %s used."
+msgstr ""
+
+#: src/Metrics/StorageFactory.php
+msgid "APCu fetch operation returned unexpected value."
+msgstr ""

src/Admin/DashboardProvider.php

@@ -0,0 +1,151 @@
+<?php
+/**
+ * Dashboard provider class.
+ *
+ * @package WP_Prometheus
+ */
+
+namespace Magdev\WpPrometheus\Admin;
+
+// Prevent direct file access.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * DashboardProvider class.
+ *
+ * Provides Grafana dashboard templates for download.
+ */
+class DashboardProvider {
+
+	/**
+	 * Dashboard directory path.
+	 *
+	 * @var string
+	 */
+	private string $dashboard_dir;
+
+	/**
+	 * Available dashboard definitions.
+	 *
+	 * @var array
+	 */
+	private array $dashboards = array();
+
+	/**
+	 * Constructor.
+	 */
+	public function __construct() {
+		$this->dashboard_dir = WP_PROMETHEUS_PATH . 'assets/dashboards/';
+
+		$this->dashboards = array(
+			'wordpress-overview'    => array(
+				'title'       => __( 'WordPress Overview', 'wp-prometheus' ),
+				'description' => __( 'General WordPress metrics including users, posts, comments, and plugins.', 'wp-prometheus' ),
+				'file'        => 'wordpress-overview.json',
+				'icon'        => 'dashicons-wordpress',
+			),
+			'wordpress-runtime'     => array(
+				'title'       => __( 'Runtime Performance', 'wp-prometheus' ),
+				'description' => __( 'HTTP request metrics, database query performance, and response times.', 'wp-prometheus' ),
+				'file'        => 'wordpress-runtime.json',
+				'icon'        => 'dashicons-performance',
+			),
+			'wordpress-woocommerce' => array(
+				'title'       => __( 'WooCommerce Store', 'wp-prometheus' ),
+				'description' => __( 'WooCommerce metrics including products, orders, revenue, and customers.', 'wp-prometheus' ),
+				'file'        => 'wordpress-woocommerce.json',
+				'icon'        => 'dashicons-cart',
+			),
+		);
+	}
+
+	/**
+	 * Get list of available dashboards.
+	 *
+	 * @return array
+	 */
+	public function get_available(): array {
+		$available = array();
+
+		foreach ( $this->dashboards as $slug => $dashboard ) {
+			$file_path = $this->dashboard_dir . $dashboard['file'];
+			if ( file_exists( $file_path ) ) {
+				$available[ $slug ] = $dashboard;
+			}
+		}
+
+		return $available;
+	}
+
+	/**
+	 * Get dashboard content by slug.
+	 *
+	 * @param string $slug Dashboard slug.
+	 * @return string|null JSON content or null if not found.
+	 */
+	public function get_dashboard( string $slug ): ?string {
+		// Validate slug to prevent directory traversal.
+		$slug = sanitize_file_name( $slug );
+
+		if ( ! isset( $this->dashboards[ $slug ] ) ) {
+			return null;
+		}
+
+		$file_path = $this->dashboard_dir . $this->dashboards[ $slug ]['file'];
+
+		// Security: Ensure file is within dashboard directory.
+		$real_path = realpath( $file_path );
+		$real_dir  = realpath( $this->dashboard_dir );
+
+		if ( false === $real_path || false === $real_dir || strpos( $real_path, $real_dir ) !== 0 ) {
+			return null;
+		}
+
+		if ( ! file_exists( $file_path ) || ! is_readable( $file_path ) ) {
+			return null;
+		}
+
+		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
+		$content = file_get_contents( $file_path );
+
+		if ( false === $content ) {
+			return null;
+		}
+
+		return $content;
+	}
+
+	/**
+	 * Get dashboard metadata by slug.
+	 *
+	 * @param string $slug Dashboard slug.
+	 * @return array|null Dashboard metadata or null if not found.
+	 */
+	public function get_metadata( string $slug ): ?array {
+		$slug = sanitize_file_name( $slug );
+
+		if ( ! isset( $this->dashboards[ $slug ] ) ) {
+			return null;
+		}
+
+		return $this->dashboards[ $slug ];
+	}
+
+	/**
+	 * Get filename for download.
+	 *
+	 * @param string $slug Dashboard slug.
+	 * @return string|null Filename or null if not found.
+	 */
+	public function get_filename( string $slug ): ?string {
+		$slug = sanitize_file_name( $slug );
+
+		if ( ! isset( $this->dashboards[ $slug ] ) ) {
+			return null;
+		}
+
+		return $this->dashboards[ $slug ]['file'];
+	}
+}

src/Installer.php

@@ -64,6 +64,7 @@ final class Installer {
             'wp_prometheus_enable_default_metrics',
             'wp_prometheus_enabled_metrics',
             'wp_prometheus_runtime_metrics',
+            'wp_prometheus_custom_metrics',
         );
 
         foreach ( $options as $option ) {

src/License/Manager.php

@@ -302,10 +302,47 @@ final class Manager {
      * @return bool
      */
     public static function is_license_valid(): bool {
+        // Bypass license check on localhost for development.
+        if ( self::is_localhost() ) {
+            return true;
+        }
+
         $status = get_option( self::OPTION_LICENSE_STATUS, 'unchecked' );
         return 'valid' === $status;
     }
 
+    /**
+     * Check if the current site is running on localhost.
+     *
+     * @return bool
+     */
+    public static function is_localhost(): bool {
+        $host = wp_parse_url( home_url(), PHP_URL_HOST );
+
+        $localhost_patterns = array(
+            'localhost',
+            '127.0.0.1',
+            '::1',
+        );
+
+        // Check exact matches.
+        if ( in_array( $host, $localhost_patterns, true ) ) {
+            return true;
+        }
+
+        // Check .localhost TLD (e.g., mysite.localhost).
+        if ( str_ends_with( $host, '.localhost' ) ) {
+            return true;
+        }
+
+        // Check .local TLD (common for local development).
+        if ( str_ends_with( $host, '.local' ) ) {
+            return true;
+        }
+
+        return false;
+    }
+
     /**
      * Get the license key.
      *
@@ -396,9 +433,16 @@ final class Manager {
      * @return void
      */
     private function update_cached_status( string $status, array $data = array() ): void {
+        $previous_status = get_option( self::OPTION_LICENSE_STATUS, 'unchecked' );
+
         update_option( self::OPTION_LICENSE_STATUS, $status );
         update_option( self::OPTION_LICENSE_DATA, $data );
         update_option( self::OPTION_LAST_CHECK, time() );
+
+        // Flush rewrite rules when license becomes valid to register the /metrics endpoint.
+        if ( 'valid' === $status && 'valid' !== $previous_status ) {
+            flush_rewrite_rules();
+        }
     }
 
     /**
@@ -465,6 +509,9 @@ final class Manager {
         update_option( self::OPTION_LICENSE_DATA, array() );
         delete_transient( self::TRANSIENT_LICENSE_CHECK );
 
+        // Flush rewrite rules to remove the /metrics endpoint.
+        flush_rewrite_rules();
+
         wp_send_json_success( array(
             'success' => true,
             'message' => __( 'License deactivated.', 'wp-prometheus' ),

src/Metrics/Collector.php

@@ -8,8 +8,9 @@
 namespace Magdev\WpPrometheus\Metrics;
 
 use Prometheus\CollectorRegistry;
-use Prometheus\Storage\InMemory;
 use Prometheus\RenderTextFormat;
+use Magdev\WpPrometheus\Metrics\CustomMetricBuilder;
+use Magdev\WpPrometheus\Metrics\StorageFactory;
 
 // Prevent direct file access.
 if ( ! defined( 'ABSPATH' ) ) {
@@ -41,7 +42,7 @@ class Collector {
      * Constructor.
      */
     public function __construct() {
-        $this->registry = new CollectorRegistry( new InMemory() );
+        $this->registry = new CollectorRegistry( StorageFactory::get_adapter() );
     }
 
     /**
@@ -113,6 +114,10 @@ class Collector {
         // Collect runtime metrics (HTTP requests, DB queries).
         $this->collect_runtime_metrics( $enabled_metrics );
 
+        // Collect custom user-defined metrics.
+        $custom_builder = new CustomMetricBuilder();
+        $custom_builder->register_with_collector( $this );
+
         /**
          * Fires after default metrics are collected.
          *
@@ -466,11 +471,14 @@ class Collector {
             array( 'status' )
         );
 
-        // Use WooCommerce's built-in order count function.
+        // Get all registered order statuses and count each.
-        $order_counts = wc_orders_count();
+        $statuses = wc_get_order_statuses();
 
-        foreach ( $order_counts as $status => $count ) {
+        foreach ( array_keys( $statuses ) as $status ) {
-            $gauge->set( (int) $count, array( $status ) );
+            // Remove 'wc-' prefix for the label.
+            $status_label = str_replace( 'wc-', '', $status );
+            $count        = wc_orders_count( $status );
+            $gauge->set( (int) $count, array( $status_label ) );
         }
     }
 

src/Metrics/CustomMetricBuilder.php

@@ -0,0 +1,496 @@
+<?php
+/**
+ * Custom metric builder class.
+ *
+ * @package WP_Prometheus
+ */
+
+namespace Magdev\WpPrometheus\Metrics;
+
+// Prevent direct file access.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * CustomMetricBuilder class.
+ *
+ * Manages custom user-defined Prometheus metrics.
+ */
+class CustomMetricBuilder {
+
+	/**
+	 * Option name for storing custom metrics.
+	 *
+	 * @var string
+	 */
+	const OPTION_NAME = 'wp_prometheus_custom_metrics';
+
+	/**
+	 * Export format version.
+	 *
+	 * @var string
+	 */
+	const EXPORT_VERSION = '1.0.0';
+
+	/**
+	 * Maximum number of labels per metric.
+	 *
+	 * @var int
+	 */
+	const MAX_LABELS = 5;
+
+	/**
+	 * Maximum number of label value combinations per metric.
+	 *
+	 * @var int
+	 */
+	const MAX_LABEL_VALUES = 50;
+
+	/**
+	 * Get all custom metrics.
+	 *
+	 * @return array
+	 */
+	public function get_all(): array {
+		$metrics = get_option( self::OPTION_NAME, array() );
+		return is_array( $metrics ) ? $metrics : array();
+	}
+
+	/**
+	 * Get a single metric by ID.
+	 *
+	 * @param string $id Metric ID.
+	 * @return array|null
+	 */
+	public function get( string $id ): ?array {
+		$metrics = $this->get_all();
+		return $metrics[ $id ] ?? null;
+	}
+
+	/**
+	 * Save a metric (create or update).
+	 *
+	 * @param array $metric Metric data.
+	 * @return string Metric ID.
+	 * @throws \InvalidArgumentException If validation fails.
+	 */
+	public function save( array $metric ): string {
+		$errors = $this->validate( $metric );
+		if ( ! empty( $errors ) ) {
+			throw new \InvalidArgumentException( implode( ', ', $errors ) );
+		}
+
+		$metrics = $this->get_all();
+
+		// Generate ID if not provided.
+		if ( empty( $metric['id'] ) ) {
+			$metric['id'] = wp_generate_uuid4();
+			$metric['created_at'] = time();
+		}
+
+		$metric['updated_at'] = time();
+
+		// Sanitize and normalize the metric data.
+		$metric = $this->sanitize_metric( $metric );
+
+		$metrics[ $metric['id'] ] = $metric;
+		update_option( self::OPTION_NAME, $metrics );
+
+		return $metric['id'];
+	}
+
+	/**
+	 * Delete a metric.
+	 *
+	 * @param string $id Metric ID.
+	 * @return bool True if deleted, false if not found.
+	 */
+	public function delete( string $id ): bool {
+		$metrics = $this->get_all();
+
+		if ( ! isset( $metrics[ $id ] ) ) {
+			return false;
+		}
+
+		unset( $metrics[ $id ] );
+		update_option( self::OPTION_NAME, $metrics );
+
+		return true;
+	}
+
+	/**
+	 * Validate a Prometheus metric name.
+	 *
+	 * @param string $name Metric name.
+	 * @return bool True if valid.
+	 */
+	public function validate_name( string $name ): bool {
+		// Prometheus metric names must match: [a-zA-Z_:][a-zA-Z0-9_:]*
+		return (bool) preg_match( '/^[a-zA-Z_:][a-zA-Z0-9_:]*$/', $name );
+	}
+
+	/**
+	 * Validate a Prometheus label name.
+	 *
+	 * @param string $name Label name.
+	 * @return bool True if valid.
+	 */
+	public function validate_label_name( string $name ): bool {
+		// Prometheus label names must match: [a-zA-Z_][a-zA-Z0-9_]*
+		// Labels starting with __ are reserved.
+		if ( strpos( $name, '__' ) === 0 ) {
+			return false;
+		}
+		return (bool) preg_match( '/^[a-zA-Z_][a-zA-Z0-9_]*$/', $name );
+	}
+
+	/**
+	 * Validate a complete metric definition.
+	 *
+	 * @param array $metric Metric data.
+	 * @return array Array of error messages (empty if valid).
+	 */
+	public function validate( array $metric ): array {
+		$errors = array();
+
+		// Name is required.
+		if ( empty( $metric['name'] ) ) {
+			$errors[] = __( 'Metric name is required.', 'wp-prometheus' );
+		} elseif ( ! $this->validate_name( $metric['name'] ) ) {
+			$errors[] = __( 'Metric name must start with a letter, underscore, or colon, and contain only letters, numbers, underscores, and colons.', 'wp-prometheus' );
+		}
+
+		// Check for reserved prefixes.
+		if ( ! empty( $metric['name'] ) ) {
+			$reserved_prefixes = array( 'wordpress_', 'go_', 'process_', 'promhttp_' );
+			foreach ( $reserved_prefixes as $prefix ) {
+				if ( strpos( $metric['name'], $prefix ) === 0 ) {
+					$errors[] = sprintf(
+						/* translators: %s: Reserved prefix */
+						__( 'Metric name cannot start with reserved prefix "%s".', 'wp-prometheus' ),
+						$prefix
+					);
+					break;
+				}
+			}
+		}
+
+		// Check for duplicate names (excluding current metric if editing).
+		if ( ! empty( $metric['name'] ) ) {
+			$existing = $this->get_all();
+			foreach ( $existing as $id => $existing_metric ) {
+				if ( $existing_metric['name'] === $metric['name'] && ( empty( $metric['id'] ) || $metric['id'] !== $id ) ) {
+					$errors[] = __( 'A metric with this name already exists.', 'wp-prometheus' );
+					break;
+				}
+			}
+		}
+
+		// Help text is required.
+		if ( empty( $metric['help'] ) ) {
+			$errors[] = __( 'Help text is required.', 'wp-prometheus' );
+		}
+
+		// Validate type.
+		$valid_types = array( 'gauge' );
+		if ( empty( $metric['type'] ) || ! in_array( $metric['type'], $valid_types, true ) ) {
+			$errors[] = __( 'Invalid metric type. Only gauge is supported.', 'wp-prometheus' );
+		}
+
+		// Validate labels.
+		if ( ! empty( $metric['labels'] ) ) {
+			if ( ! is_array( $metric['labels'] ) ) {
+				$errors[] = __( 'Labels must be an array.', 'wp-prometheus' );
+			} elseif ( count( $metric['labels'] ) > self::MAX_LABELS ) {
+				$errors[] = sprintf(
+					/* translators: %d: Maximum labels */
+					__( 'Maximum %d labels allowed per metric.', 'wp-prometheus' ),
+					self::MAX_LABELS
+				);
+			} else {
+				foreach ( $metric['labels'] as $label ) {
+					if ( ! $this->validate_label_name( $label ) ) {
+						$errors[] = sprintf(
+							/* translators: %s: Label name */
+							__( 'Invalid label name: %s', 'wp-prometheus' ),
+							$label
+						);
+					}
+				}
+			}
+		}
+
+		// Validate value type.
+		$valid_value_types = array( 'static', 'option' );
+		if ( empty( $metric['value_type'] ) || ! in_array( $metric['value_type'], $valid_value_types, true ) ) {
+			$errors[] = __( 'Invalid value type. Must be "static" or "option".', 'wp-prometheus' );
+		}
+
+		// Validate value config based on type.
+		if ( ! empty( $metric['value_type'] ) ) {
+			if ( 'static' === $metric['value_type'] ) {
+				// Static values validated in label_values.
+			} elseif ( 'option' === $metric['value_type'] ) {
+				if ( empty( $metric['value_config']['option_name'] ) ) {
+					$errors[] = __( 'Option name is required for option-based metrics.', 'wp-prometheus' );
+				}
+			}
+		}
+
+		// Validate label values count.
+		if ( ! empty( $metric['label_values'] ) && is_array( $metric['label_values'] ) ) {
+			if ( count( $metric['label_values'] ) > self::MAX_LABEL_VALUES ) {
+				$errors[] = sprintf(
+					/* translators: %d: Maximum label combinations */
+					__( 'Maximum %d label value combinations allowed.', 'wp-prometheus' ),
+					self::MAX_LABEL_VALUES
+				);
+			}
+
+			// Validate each row has correct number of values.
+			$label_count = count( $metric['labels'] ?? array() );
+			foreach ( $metric['label_values'] as $row ) {
+				if ( is_array( $row ) && count( $row ) !== $label_count + 1 ) { // +1 for value.
+					$errors[] = __( 'Each label value row must have values for all labels plus a metric value.', 'wp-prometheus' );
+					break;
+				}
+			}
+		}
+
+		return $errors;
+	}
+
+	/**
+	 * Sanitize metric data.
+	 *
+	 * @param array $metric Raw metric data.
+	 * @return array Sanitized metric data.
+	 */
+	private function sanitize_metric( array $metric ): array {
+		$sanitized = array(
+			'id'           => sanitize_key( $metric['id'] ?? '' ),
+			'name'         => sanitize_key( $metric['name'] ?? '' ),
+			'help'         => sanitize_text_field( $metric['help'] ?? '' ),
+			'type'         => sanitize_key( $metric['type'] ?? 'gauge' ),
+			'labels'       => array(),
+			'value_type'   => sanitize_key( $metric['value_type'] ?? 'static' ),
+			'value_config' => array(),
+			'label_values' => array(),
+			'enabled'      => ! empty( $metric['enabled'] ),
+			'created_at'   => absint( $metric['created_at'] ?? time() ),
+			'updated_at'   => absint( $metric['updated_at'] ?? time() ),
+		);
+
+		// Sanitize labels.
+		if ( ! empty( $metric['labels'] ) && is_array( $metric['labels'] ) ) {
+			foreach ( $metric['labels'] as $label ) {
+				$sanitized['labels'][] = sanitize_key( $label );
+			}
+		}
+
+		// Sanitize value config.
+		if ( 'static' === $sanitized['value_type'] ) {
+			$sanitized['value_config'] = array();
+		} elseif ( 'option' === $sanitized['value_type'] ) {
+			$sanitized['value_config'] = array(
+				'option_name' => sanitize_key( $metric['value_config']['option_name'] ?? '' ),
+				'default'     => floatval( $metric['value_config']['default'] ?? 0 ),
+			);
+		}
+
+		// Sanitize label values.
+		if ( ! empty( $metric['label_values'] ) && is_array( $metric['label_values'] ) ) {
+			foreach ( $metric['label_values'] as $row ) {
+				if ( is_array( $row ) ) {
+					$sanitized_row = array();
+					foreach ( $row as $index => $value ) {
+						// Last value is the metric value (numeric).
+						if ( $index === count( $row ) - 1 ) {
+							$sanitized_row[] = floatval( $value );
+						} else {
+							$sanitized_row[] = sanitize_text_field( $value );
+						}
+					}
+					$sanitized['label_values'][] = $sanitized_row;
+				}
+			}
+		}
+
+		return $sanitized;
+	}
+
+	/**
+	 * Export all metrics to JSON.
+	 *
+	 * @return string JSON string.
+	 */
+	public function export(): string {
+		$metrics = $this->get_all();
+
+		$export_data = array(
+			'version'        => self::EXPORT_VERSION,
+			'plugin_version' => WP_PROMETHEUS_VERSION,
+			'exported_at'    => gmdate( 'c' ),
+			'site_url'       => home_url(),
+			'metrics'        => array_values( $metrics ),
+		);
+
+		return wp_json_encode( $export_data, JSON_PRETTY_PRINT );
+	}
+
+	/**
+	 * Import metrics from JSON.
+	 *
+	 * @param string $json      JSON string.
+	 * @param string $mode      Import mode: 'skip', 'overwrite', or 'rename'.
+	 * @return array Result with 'imported', 'skipped', 'errors' counts.
+	 * @throws \InvalidArgumentException If JSON is invalid.
+	 */
+	public function import( string $json, string $mode = 'skip' ): array {
+		$data = json_decode( $json, true );
+
+		if ( json_last_error() !== JSON_ERROR_NONE ) {
+			throw new \InvalidArgumentException( __( 'Invalid JSON format.', 'wp-prometheus' ) );
+		}
+
+		if ( empty( $data['metrics'] ) || ! is_array( $data['metrics'] ) ) {
+			throw new \InvalidArgumentException( __( 'No metrics found in import file.', 'wp-prometheus' ) );
+		}
+
+		$result = array(
+			'imported' => 0,
+			'skipped'  => 0,
+			'errors'   => 0,
+			'messages' => array(),
+		);
+
+		$existing_metrics = $this->get_all();
+		$existing_names   = array_column( $existing_metrics, 'name', 'id' );
+
+		foreach ( $data['metrics'] as $metric ) {
+			if ( empty( $metric['name'] ) ) {
+				$result['errors']++;
+				continue;
+			}
+
+			// Check for name collision.
+			$name_exists = in_array( $metric['name'], $existing_names, true );
+
+			if ( $name_exists ) {
+				if ( 'skip' === $mode ) {
+					$result['skipped']++;
+					$result['messages'][] = sprintf(
+						/* translators: %s: Metric name */
+						__( 'Skipped "%s" (already exists).', 'wp-prometheus' ),
+						$metric['name']
+					);
+					continue;
+				} elseif ( 'rename' === $mode ) {
+					// Generate unique name.
+					$base_name = $metric['name'];
+					$counter   = 1;
+					while ( in_array( $metric['name'], $existing_names, true ) ) {
+						$metric['name'] = $base_name . '_imported_' . $counter;
+						$counter++;
+					}
+				}
+				// 'overwrite' mode: continue with same name, will overwrite below.
+			}
+
+			// Clear ID to create new metric (unless overwriting).
+			if ( 'overwrite' === $mode && $name_exists ) {
+				// Find existing ID by name.
+				$metric['id'] = array_search( $metric['name'], $existing_names, true );
+			} else {
+				unset( $metric['id'] );
+			}
+
+			try {
+				$this->save( $metric );
+				$result['imported']++;
+
+				// Update existing names for subsequent collision checks.
+				$existing_names = array_column( $this->get_all(), 'name', 'id' );
+			} catch ( \InvalidArgumentException $e ) {
+				$result['errors']++;
+				$result['messages'][] = sprintf(
+					/* translators: 1: Metric name, 2: Error message */
+					__( 'Error importing "%1$s": %2$s', 'wp-prometheus' ),
+					$metric['name'],
+					$e->getMessage()
+				);
+			}
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Register custom metrics with the Collector.
+	 *
+	 * @param Collector $collector The metrics collector instance.
+	 * @return void
+	 */
+	public function register_with_collector( Collector $collector ): void {
+		$metrics = $this->get_all();
+
+		foreach ( $metrics as $metric ) {
+			if ( empty( $metric['enabled'] ) ) {
+				continue;
+			}
+
+			try {
+				$gauge = $collector->register_gauge(
+					$metric['name'],
+					$metric['help'],
+					$metric['labels'] ?? array()
+				);
+
+				// Set values based on value type.
+				if ( 'option' === $metric['value_type'] ) {
+					// Option-based metric: read from WordPress option.
+					$option_name = $metric['value_config']['option_name'] ?? '';
+					$default     = $metric['value_config']['default'] ?? 0;
+
+					if ( ! empty( $option_name ) ) {
+						$value = get_option( $option_name, $default );
+						$value = is_numeric( $value ) ? floatval( $value ) : $default;
+
+						// For option-based, use empty labels if no labels defined.
+						$label_values = array();
+						if ( ! empty( $metric['labels'] ) && ! empty( $metric['label_values'][0] ) ) {
+							// Use first row of labels (without the value).
+							$label_values = array_slice( $metric['label_values'][0], 0, count( $metric['labels'] ) );
+						}
+
+						$gauge->set( $value, $label_values );
+					}
+				} elseif ( 'static' === $metric['value_type'] ) {
+					// Static metric: use predefined label values.
+					if ( ! empty( $metric['label_values'] ) ) {
+						foreach ( $metric['label_values'] as $row ) {
+							if ( ! is_array( $row ) || count( $row ) < 1 ) {
+								continue;
+							}
+
+							// Last element is the value.
+							$value = array_pop( $row );
+
+							// Remaining elements are label values.
+							$gauge->set( floatval( $value ), $row );
+						}
+					} else {
+						// No labels, single value.
+						$gauge->set( 0, array() );
+					}
+				}
+			} catch ( \Exception $e ) {
+				// Log error but don't break metric collection.
+				if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
+					error_log( sprintf( 'WP Prometheus: Failed to register custom metric "%s": %s', $metric['name'], $e->getMessage() ) );
+				}
+			}
+		}
+	}
+}

src/Metrics/StorageFactory.php

@@ -0,0 +1,502 @@
+<?php
+/**
+ * Storage factory for Prometheus metrics.
+ *
+ * @package WP_Prometheus
+ */
+
+namespace Magdev\WpPrometheus\Metrics;
+
+use Prometheus\Storage\Adapter;
+use Prometheus\Storage\InMemory;
+use Prometheus\Storage\Redis;
+use Prometheus\Storage\APC;
+use Prometheus\Exception\StorageException;
+
+// Prevent direct file access.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * StorageFactory class.
+ *
+ * Creates and configures storage adapters for Prometheus metrics.
+ * Supports configuration via WordPress options or environment variables.
+ */
+class StorageFactory {
+
+	/**
+	 * Available storage adapters.
+	 */
+	public const ADAPTER_INMEMORY = 'inmemory';
+	public const ADAPTER_REDIS    = 'redis';
+	public const ADAPTER_APCU     = 'apcu';
+
+	/**
+	 * Environment variable names.
+	 */
+	private const ENV_STORAGE_ADAPTER  = 'WP_PROMETHEUS_STORAGE_ADAPTER';
+	private const ENV_REDIS_HOST       = 'WP_PROMETHEUS_REDIS_HOST';
+	private const ENV_REDIS_PORT       = 'WP_PROMETHEUS_REDIS_PORT';
+	private const ENV_REDIS_PASSWORD   = 'WP_PROMETHEUS_REDIS_PASSWORD';
+	private const ENV_REDIS_DATABASE   = 'WP_PROMETHEUS_REDIS_DATABASE';
+	private const ENV_REDIS_PREFIX     = 'WP_PROMETHEUS_REDIS_PREFIX';
+	private const ENV_APCU_PREFIX      = 'WP_PROMETHEUS_APCU_PREFIX';
+
+	/**
+	 * Default Redis prefix.
+	 */
+	private const DEFAULT_REDIS_PREFIX = 'WORDPRESS_PROMETHEUS_';
+
+	/**
+	 * Default APCu prefix.
+	 */
+	private const DEFAULT_APCU_PREFIX = 'wp_prom';
+
+	/**
+	 * Singleton instance of the storage adapter.
+	 *
+	 * @var Adapter|null
+	 */
+	private static ?Adapter $instance = null;
+
+	/**
+	 * Last error message.
+	 *
+	 * @var string
+	 */
+	private static string $last_error = '';
+
+	/**
+	 * Get the storage adapter instance.
+	 *
+	 * @return Adapter
+	 */
+	public static function get_adapter(): Adapter {
+		if ( null === self::$instance ) {
+			self::$instance = self::create_adapter();
+		}
+		return self::$instance;
+	}
+
+	/**
+	 * Reset the singleton instance (useful for testing or config changes).
+	 *
+	 * @return void
+	 */
+	public static function reset(): void {
+		self::$instance = null;
+		self::$last_error = '';
+	}
+
+	/**
+	 * Get the last error message.
+	 *
+	 * @return string
+	 */
+	public static function get_last_error(): string {
+		return self::$last_error;
+	}
+
+	/**
+	 * Get available storage adapters.
+	 *
+	 * @return array<string, string>
+	 */
+	public static function get_available_adapters(): array {
+		return array(
+			self::ADAPTER_INMEMORY => __( 'In-Memory (default, no persistence)', 'wp-prometheus' ),
+			self::ADAPTER_REDIS    => __( 'Redis (requires PHP Redis extension)', 'wp-prometheus' ),
+			self::ADAPTER_APCU     => __( 'APCu (requires APCu extension)', 'wp-prometheus' ),
+		);
+	}
+
+	/**
+	 * Check if a storage adapter is available on this system.
+	 *
+	 * @param string $adapter Adapter name.
+	 * @return bool
+	 */
+	public static function is_adapter_available( string $adapter ): bool {
+		switch ( $adapter ) {
+			case self::ADAPTER_INMEMORY:
+				return true;
+
+			case self::ADAPTER_REDIS:
+				return extension_loaded( 'redis' );
+
+			case self::ADAPTER_APCU:
+				return extension_loaded( 'apcu' ) && apcu_enabled();
+
+			default:
+				return false;
+		}
+	}
+
+	/**
+	 * Get the configured storage adapter name.
+	 *
+	 * @return string
+	 */
+	public static function get_configured_adapter(): string {
+		// Check environment variable first.
+		$env_adapter = getenv( self::ENV_STORAGE_ADAPTER );
+		if ( false !== $env_adapter && ! empty( $env_adapter ) ) {
+			return strtolower( $env_adapter );
+		}
+
+		// Fall back to WordPress option.
+		return get_option( 'wp_prometheus_storage_adapter', self::ADAPTER_INMEMORY );
+	}
+
+	/**
+	 * Get the active storage adapter name (may differ from configured if fallback occurred).
+	 *
+	 * @return string
+	 */
+	public static function get_active_adapter(): string {
+		// Ensure adapter is created.
+		self::get_adapter();
+
+		$configured = self::get_configured_adapter();
+		if ( self::is_adapter_available( $configured ) && empty( self::$last_error ) ) {
+			return $configured;
+		}
+
+		return self::ADAPTER_INMEMORY;
+	}
+
+	/**
+	 * Create the storage adapter based on configuration.
+	 *
+	 * @return Adapter
+	 */
+	private static function create_adapter(): Adapter {
+		$adapter = self::get_configured_adapter();
+		self::$last_error = '';
+
+		switch ( $adapter ) {
+			case self::ADAPTER_REDIS:
+				return self::create_redis_adapter();
+
+			case self::ADAPTER_APCU:
+				return self::create_apcu_adapter();
+
+			case self::ADAPTER_INMEMORY:
+			default:
+				return new InMemory();
+		}
+	}
+
+	/**
+	 * Create Redis storage adapter.
+	 *
+	 * @return Adapter
+	 */
+	private static function create_redis_adapter(): Adapter {
+		if ( ! extension_loaded( 'redis' ) ) {
+			self::$last_error = __( 'PHP Redis extension is not installed.', 'wp-prometheus' );
+			return new InMemory();
+		}
+
+		$config = self::get_redis_config();
+
+		try {
+			Redis::setPrefix( $config['prefix'] );
+
+			$redis = new Redis( array(
+				'host'                   => $config['host'],
+				'port'                   => $config['port'],
+				'password'               => $config['password'] ?: null,
+				'timeout'                => 0.5,
+				'read_timeout'           => 10,
+				'persistent_connections' => true,
+			) );
+
+			// Test connection by triggering initialization.
+			// The Redis adapter connects lazily, so we need to check it works.
+			return $redis;
+		} catch ( StorageException $e ) {
+			self::$last_error = sprintf(
+				/* translators: %s: Error message */
+				__( 'Redis connection failed: %s', 'wp-prometheus' ),
+				$e->getMessage()
+			);
+			return new InMemory();
+		} catch ( \RedisException $e ) {
+			self::$last_error = sprintf(
+				/* translators: %s: Error message */
+				__( 'Redis error: %s', 'wp-prometheus' ),
+				$e->getMessage()
+			);
+			return new InMemory();
+		} catch ( \Exception $e ) {
+			self::$last_error = sprintf(
+				/* translators: %s: Error message */
+				__( 'Storage error: %s', 'wp-prometheus' ),
+				$e->getMessage()
+			);
+			return new InMemory();
+		}
+	}
+
+	/**
+	 * Create APCu storage adapter.
+	 *
+	 * @return Adapter
+	 */
+	private static function create_apcu_adapter(): Adapter {
+		if ( ! extension_loaded( 'apcu' ) ) {
+			self::$last_error = __( 'APCu extension is not installed.', 'wp-prometheus' );
+			return new InMemory();
+		}
+
+		if ( ! apcu_enabled() ) {
+			self::$last_error = __( 'APCu is installed but not enabled.', 'wp-prometheus' );
+			return new InMemory();
+		}
+
+		$prefix = self::get_apcu_prefix();
+
+		try {
+			return new APC( $prefix );
+		} catch ( StorageException $e ) {
+			self::$last_error = sprintf(
+				/* translators: %s: Error message */
+				__( 'APCu error: %s', 'wp-prometheus' ),
+				$e->getMessage()
+			);
+			return new InMemory();
+		}
+	}
+
+	/**
+	 * Get Redis configuration.
+	 *
+	 * @return array{host: string, port: int, password: string, database: int, prefix: string}
+	 */
+	public static function get_redis_config(): array {
+		// Check environment variables first.
+		$env_host = getenv( self::ENV_REDIS_HOST );
+		$env_port = getenv( self::ENV_REDIS_PORT );
+		$env_password = getenv( self::ENV_REDIS_PASSWORD );
+		$env_database = getenv( self::ENV_REDIS_DATABASE );
+		$env_prefix = getenv( self::ENV_REDIS_PREFIX );
+
+		// Get WordPress options as fallback.
+		$options = get_option( 'wp_prometheus_redis_config', array() );
+
+		return array(
+			'host'     => ( false !== $env_host && ! empty( $env_host ) ) ? $env_host : ( $options['host'] ?? '127.0.0.1' ),
+			'port'     => ( false !== $env_port && ! empty( $env_port ) ) ? (int) $env_port : ( (int) ( $options['port'] ?? 6379 ) ),
+			'password' => ( false !== $env_password ) ? $env_password : ( $options['password'] ?? '' ),
+			'database' => ( false !== $env_database && ! empty( $env_database ) ) ? (int) $env_database : ( (int) ( $options['database'] ?? 0 ) ),
+			'prefix'   => ( false !== $env_prefix && ! empty( $env_prefix ) ) ? $env_prefix : ( $options['prefix'] ?? self::DEFAULT_REDIS_PREFIX ),
+		);
+	}
+
+	/**
+	 * Get APCu prefix.
+	 *
+	 * @return string
+	 */
+	public static function get_apcu_prefix(): string {
+		$env_prefix = getenv( self::ENV_APCU_PREFIX );
+		if ( false !== $env_prefix && ! empty( $env_prefix ) ) {
+			return $env_prefix;
+		}
+
+		return get_option( 'wp_prometheus_apcu_prefix', self::DEFAULT_APCU_PREFIX );
+	}
+
+	/**
+	 * Save storage configuration.
+	 *
+	 * @param array $config Configuration array.
+	 * @return void
+	 */
+	public static function save_config( array $config ): void {
+		if ( isset( $config['adapter'] ) ) {
+			update_option( 'wp_prometheus_storage_adapter', sanitize_key( $config['adapter'] ) );
+		}
+
+		if ( isset( $config['redis'] ) && is_array( $config['redis'] ) ) {
+			$redis_config = array(
+				'host'     => sanitize_text_field( $config['redis']['host'] ?? '127.0.0.1' ),
+				'port'     => absint( $config['redis']['port'] ?? 6379 ),
+				'password' => sanitize_text_field( $config['redis']['password'] ?? '' ),
+				'database' => absint( $config['redis']['database'] ?? 0 ),
+				'prefix'   => sanitize_key( $config['redis']['prefix'] ?? self::DEFAULT_REDIS_PREFIX ),
+			);
+			update_option( 'wp_prometheus_redis_config', $redis_config );
+		}
+
+		if ( isset( $config['apcu_prefix'] ) ) {
+			update_option( 'wp_prometheus_apcu_prefix', sanitize_key( $config['apcu_prefix'] ) );
+		}
+
+		// Reset the singleton to apply new configuration.
+		self::reset();
+	}
+
+	/**
+	 * Test storage adapter connection.
+	 *
+	 * @param string $adapter Adapter name.
+	 * @param array  $config  Optional configuration to test.
+	 * @return array{success: bool, message: string}
+	 */
+	public static function test_connection( string $adapter, array $config = array() ): array {
+		switch ( $adapter ) {
+			case self::ADAPTER_REDIS:
+				return self::test_redis_connection( $config );
+
+			case self::ADAPTER_APCU:
+				return self::test_apcu_connection( $config );
+
+			case self::ADAPTER_INMEMORY:
+				return array(
+					'success' => true,
+					'message' => __( 'In-Memory storage is always available.', 'wp-prometheus' ),
+				);
+
+			default:
+				return array(
+					'success' => false,
+					'message' => __( 'Unknown storage adapter.', 'wp-prometheus' ),
+				);
+		}
+	}
+
+	/**
+	 * Test Redis connection.
+	 *
+	 * @param array $config Redis configuration.
+	 * @return array{success: bool, message: string}
+	 */
+	private static function test_redis_connection( array $config ): array {
+		if ( ! extension_loaded( 'redis' ) ) {
+			return array(
+				'success' => false,
+				'message' => __( 'PHP Redis extension is not installed.', 'wp-prometheus' ),
+			);
+		}
+
+		$redis_config = ! empty( $config ) ? $config : self::get_redis_config();
+
+		try {
+			$redis = new \Redis();
+
+			$connected = $redis->connect(
+				$redis_config['host'],
+				$redis_config['port'],
+				0.5 // timeout
+			);
+
+			if ( ! $connected ) {
+				return array(
+					'success' => false,
+					'message' => __( 'Could not connect to Redis server.', 'wp-prometheus' ),
+				);
+			}
+
+			if ( ! empty( $redis_config['password'] ) ) {
+				$authenticated = $redis->auth( $redis_config['password'] );
+				if ( ! $authenticated ) {
+					return array(
+						'success' => false,
+						'message' => __( 'Redis authentication failed.', 'wp-prometheus' ),
+					);
+				}
+			}
+
+			if ( $redis_config['database'] > 0 ) {
+				$redis->select( $redis_config['database'] );
+			}
+
+			// Test with a ping.
+			$pong = $redis->ping();
+			$redis->close();
+
+			if ( $pong ) {
+				return array(
+					'success' => true,
+					'message' => sprintf(
+						/* translators: %s: Redis host:port */
+						__( 'Successfully connected to Redis at %s.', 'wp-prometheus' ),
+						$redis_config['host'] . ':' . $redis_config['port']
+					),
+				);
+			}
+
+			return array(
+				'success' => false,
+				'message' => __( 'Redis ping failed.', 'wp-prometheus' ),
+			);
+		} catch ( \RedisException $e ) {
+			return array(
+				'success' => false,
+				'message' => sprintf(
+					/* translators: %s: Error message */
+					__( 'Redis error: %s', 'wp-prometheus' ),
+					$e->getMessage()
+				),
+			);
+		}
+	}
+
+	/**
+	 * Test APCu connection.
+	 *
+	 * @param array $config APCu configuration.
+	 * @return array{success: bool, message: string}
+	 */
+	private static function test_apcu_connection( array $config ): array {
+		if ( ! extension_loaded( 'apcu' ) ) {
+			return array(
+				'success' => false,
+				'message' => __( 'APCu extension is not installed.', 'wp-prometheus' ),
+			);
+		}
+
+		if ( ! apcu_enabled() ) {
+			return array(
+				'success' => false,
+				'message' => __( 'APCu is installed but not enabled. Check your php.ini settings.', 'wp-prometheus' ),
+			);
+		}
+
+		// Test with a simple store/fetch.
+		$test_key = 'wp_prometheus_test_' . time();
+		$test_value = 'test_' . wp_rand();
+
+		$stored = apcu_store( $test_key, $test_value, 5 );
+		if ( ! $stored ) {
+			return array(
+				'success' => false,
+				'message' => __( 'APCu store operation failed.', 'wp-prometheus' ),
+			);
+		}
+
+		$fetched = apcu_fetch( $test_key );
+		apcu_delete( $test_key );
+
+		if ( $fetched === $test_value ) {
+			$info = apcu_cache_info( true );
+			return array(
+				'success' => true,
+				'message' => sprintf(
+					/* translators: %s: Memory info */
+					__( 'APCu is working. Memory: %s used.', 'wp-prometheus' ),
+					size_format( $info['mem_size'] ?? 0 )
+				),
+			);
+		}
+
+		return array(
+			'success' => false,
+			'message' => __( 'APCu fetch operation returned unexpected value.', 'wp-prometheus' ),
+		);
+	}
+}

wp-prometheus.php

@@ -3,7 +3,7 @@
  * Plugin Name: WP Prometheus
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wp-prometheus
  * Description: Prometheus metrics endpoint for WordPress with extensible hooks for custom metrics.
- * Version: 0.2.0
+ * Version: 0.4.0
  * Requires at least: 6.4
  * Requires PHP: 8.3
  * Author: Marco Graetsch
@@ -26,7 +26,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  *
  * @var string
  */
-define( 'WP_PROMETHEUS_VERSION', '0.2.0' );
+define( 'WP_PROMETHEUS_VERSION', '0.4.0' );
 
 /**
  * Plugin file path.