expose frigate_camera_events as a gauge

The metric reports the current count of events in the database, which drops when retention prunes old events. As a counter, each prune read as a counter reset, so increase() and rate() inflated event counts. The series name changes from frigate_camera_events_total to frigate_camera_events. The test's porch/inside assertion was missing its `in event.text` and always passed.

docs/docs/configuration/metrics.md

@@ -69,7 +69,7 @@ These gauges report the operating system's figures for the whole filesystem (the
 
 ### Event Metrics
 
-- `frigate_camera_events{camera="", label=""}` - Count of camera events since exporter started
+- `frigate_camera_events{camera="", label=""}` - Current number of events stored in the database for each camera and label
 
 ## Configuring Prometheus
 
@@ -101,8 +101,8 @@ rate(frigate_detection_fps{camera_name="front_door"}[5m])
 # Storage usage percentage
 (frigate_storage_used_bytes / frigate_storage_total_bytes) * 100
 
-# Event count by camera in last hour
+# Number of events currently stored in the database by camera
-increase(frigate_camera_events[1h])
+sum by (camera) (frigate_camera_events)
 ```
 
 ## Grafana Dashboard
@@ -121,8 +121,7 @@ A sample Grafana dashboard JSON will be provided in a future update.
 
 The metrics exposed by Frigate use the following Prometheus metric types:
 
-- **Counter**: Cumulative values that only increase (e.g., `frigate_camera_events`)
+- **Gauge**: Values that can go up and down (e.g., `frigate_cpu_usage_percent`, `frigate_camera_events`)
-- **Gauge**: Values that can go up and down (e.g., `frigate_cpu_usage_percent`)
 - **Info**: Key-value pairs for metadata (e.g., `frigate_storage_mount_type`)
 
 For more information about Prometheus metric types, see the [Prometheus documentation](https://prometheus.io/docs/concepts/metric_types/).

frigate/stats/prometheus.py

@@ -5,7 +5,6 @@ from typing import Any
 from prometheus_client import CONTENT_TYPE_LATEST, generate_latest
 from prometheus_client.core import (
     REGISTRY,
-    CounterMetricFamily,
     GaugeMetricFamily,
     InfoMetricFamily,
 )
@@ -472,9 +471,9 @@ class CustomCollector:
         yield storage_total
         yield storage_used
 
-        camera_events = CounterMetricFamily(
+        camera_events = GaugeMetricFamily(
             "frigate_camera_events",
-            "Count of camera events since exporter started",
+            "Current number of events stored in the database per camera and label",
             labels=["camera", "label"],
         )
 

frigate/test/http_api/test_http_event.py

@@ -563,23 +563,20 @@ class TestHttpApp(BaseTestHttp):
         assert "# TYPE frigate_detection_total_fps gauge" in event.text
         assert "frigate_detection_total_fps 13.7" in event.text
         assert (
-            "# HELP frigate_camera_events_total Count of camera events since exporter started"
+            "# HELP frigate_camera_events Current number of events stored in the database per camera and label"
             in event.text
         )
-        assert "# TYPE frigate_camera_events_total counter" in event.text
+        assert "# TYPE frigate_camera_events gauge" in event.text
         assert (
-            'frigate_camera_events_total{camera="front_door",label="Mock"} 3.0'
+            'frigate_camera_events{camera="front_door",label="Mock"} 3.0' in event.text
+        )
+        assert (
+            'frigate_camera_events{camera="front_door",label="inside"} 2.0'
             in event.text
         )
         assert (
-            'frigate_camera_events_total{camera="front_door",label="inside"} 2.0'
+            'frigate_camera_events{camera="front_door",label="outside"} 2.0'
             in event.text
         )
-        assert (
+        assert 'frigate_camera_events{camera="porch",label="Mock"} 2.0' in event.text
-            'frigate_camera_events_total{camera="front_door",label="outside"} 2.0'
+        assert 'frigate_camera_events{camera="porch",label="inside"} 2.0' in event.text
-            in event.text
-        )
-        assert (
-            'frigate_camera_events_total{camera="porch",label="Mock"} 2.0' in event.text
-        )
-        assert 'frigate_camera_events_total{camera="porch",label="inside"} 2.0'