Add counter entities support to Prometheus component (#62410)

homeassistant/components/prometheus/__init__.py

@@ -515,6 +515,15 @@ class PrometheusMetrics:
 
         metric.labels(**self._labels(state)).inc()
 
+    def _handle_counter(self, state):
+        metric = self._metric(
+            "counter_value",
+            self.prometheus_cli.Gauge,
+            "Value of counter entities",
+        )
+
+        metric.labels(**self._labels(state)).set(self.state_as_number(state))
+
 
 class PrometheusView(HomeAssistantView):
     """Handle Prometheus requests."""

tests/components/prometheus/test_init.py

@@ -7,7 +7,7 @@ import unittest.mock as mock
 import prometheus_client
 import pytest
 
-from homeassistant.components import climate, humidifier, lock, sensor
+from homeassistant.components import climate, counter, humidifier, lock, sensor
 from homeassistant.components.demo.binary_sensor import DemoBinarySensor
 from homeassistant.components.demo.light import DemoLight
 from homeassistant.components.demo.number import DemoNumber
@@ -662,6 +662,31 @@ async def test_lock(hass, hass_client):
     )
 
 
+async def test_counter(hass, hass_client):
+    """Test prometheus metrics for counter."""
+    assert await async_setup_component(
+        hass,
+        "conversation",
+        {},
+    )
+
+    client = await setup_prometheus_client(hass, hass_client, "")
+
+    await async_setup_component(
+        hass, counter.DOMAIN, {"counter": {"counter": {"initial": "2"}}}
+    )
+
+    await hass.async_block_till_done()
+
+    body = await generate_latest_metrics(client)
+
+    assert (
+        'counter_value{domain="counter",'
+        'entity="counter.counter",'
+        'friendly_name="None"} 2.0' in body
+    )
+
+
 @pytest.fixture(name="mock_client")
 def mock_client_fixture():
     """Mock the prometheus client."""