Pull count of detection events by label into prometheus metrics (#20119)

* pull count of detection events by label into prometheus metrics

* format changes with ruff

* remove unneeded f-string

* fix imports format

---------

Co-authored-by: iesad <iesad>

frigate/test/http_api/test_http_event.py

@@ -8,7 +8,9 @@ from playhouse.shortcuts import model_to_dict
 from frigate.api.auth import get_allowed_cameras_for_filter, get_current_user
 from frigate.comms.event_metadata_updater import EventMetadataPublisher
 from frigate.models import Event, Recordings, ReviewSegment, Timeline
+from frigate.stats.emitter import StatsEmitter
 from frigate.test.http_api.base_http_test import BaseTestHttp
+from frigate.test.test_storage import _insert_mock_event
 
 
 class TestHttpApp(BaseTestHttp):
@@ -293,3 +295,108 @@ class TestHttpApp(BaseTestHttp):
             sub_labels = client.get("/sub_labels").json()
             assert sub_labels
             assert sub_labels == [sub_label]
+
+    ####################################################################################################################
+    ###################################  GET /metrics Endpoint   #########################################################
+    ####################################################################################################################
+    def test_get_metrics(self):
+        """ensure correct prometheus metrics api response"""
+        with TestClient(self.app) as client:
+            ts_start = datetime.now().timestamp()
+            ts_end = ts_start + 30
+            _insert_mock_event(
+                id="abcde.random", start=ts_start, end=ts_end, retain=True
+            )
+            _insert_mock_event(
+                id="01234.random", start=ts_start, end=ts_end, retain=True
+            )
+            _insert_mock_event(
+                id="56789.random", start=ts_start, end=ts_end, retain=True
+            )
+            _insert_mock_event(
+                id="101112.random",
+                label="outside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="131415.random",
+                label="outside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="161718.random",
+                camera="porch",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="192021.random",
+                camera="porch",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="222324.random",
+                camera="porch",
+                label="inside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="252627.random",
+                camera="porch",
+                label="inside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="282930.random",
+                label="inside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+            _insert_mock_event(
+                id="313233.random",
+                label="inside",
+                start=ts_start,
+                end=ts_end,
+                retain=True,
+            )
+
+            stats_emitter = Mock(spec=StatsEmitter)
+            stats_emitter.get_latest_stats.return_value = self.test_stats
+            self.app.stats_emitter = stats_emitter
+            event = client.get("/metrics")
+
+        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"
+            in event.text
+        )
+        assert "# TYPE frigate_camera_events_total counter" in event.text
+        assert (
+            'frigate_camera_events_total{camera="front_door",label="Mock"} 3.0'
+            in event.text
+        )
+        assert (
+            'frigate_camera_events_total{camera="front_door",label="inside"} 2.0'
+            in event.text
+        )
+        assert (
+            'frigate_camera_events_total{camera="front_door",label="outside"} 2.0'
+            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'

frigate/test/test_storage.py

@@ -261,12 +261,19 @@ class TestHttp(unittest.TestCase):
         assert Recordings.get(Recordings.id == rec_k3_id)
 
 
-def _insert_mock_event(id: str, start: int, end: int, retain: bool) -> Event:
+def _insert_mock_event(
+    id: str,
+    start: int,
+    end: int,
+    retain: bool,
+    camera: str = "front_door",
+    label: str = "Mock",
+) -> Event:
     """Inserts a basic event model with a given id."""
     return Event.insert(
         id=id,
-        label="Mock",
-        camera="front_door",
+        label=label,
+        camera=camera,
         start_time=start,
         end_time=end,
         top_score=100,