Add lightweight API to get core state (#96860)

homeassistant/components/api/__init__.py

@@ -18,6 +18,7 @@ from homeassistant.const import (
     URL_API,
     URL_API_COMPONENTS,
     URL_API_CONFIG,
+    URL_API_CORE_STATE,
     URL_API_ERROR_LOG,
     URL_API_EVENTS,
     URL_API_SERVICES,
@@ -55,6 +56,7 @@ CONFIG_SCHEMA = cv.empty_config_schema(DOMAIN)
 async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     """Register the API with the HTTP interface."""
     hass.http.register_view(APIStatusView)
+    hass.http.register_view(APICoreStateView)
     hass.http.register_view(APIEventStream)
     hass.http.register_view(APIConfigView)
     hass.http.register_view(APIStatesView)
@@ -84,6 +86,24 @@ class APIStatusView(HomeAssistantView):
         return self.json_message("API running.")
 
 
+class APICoreStateView(HomeAssistantView):
+    """View to handle core state requests."""
+
+    url = URL_API_CORE_STATE
+    name = "api:core:state"
+
+    @ha.callback
+    def get(self, request: web.Request) -> web.Response:
+        """Retrieve the current core state.
+
+        This API is intended to be a fast and lightweight way to check if the
+        Home Assistant core is running. Its primary use case is for supervisor
+        to check if Home Assistant is running.
+        """
+        hass: HomeAssistant = request.app["hass"]
+        return self.json({"state": hass.state.value})
+
+
 class APIEventStream(HomeAssistantView):
     """View to handle EventStream requests."""
 

homeassistant/const.py

@@ -1101,6 +1101,7 @@ SERVER_PORT: Final = 8123
 URL_ROOT: Final = "/"
 URL_API: Final = "/api/"
 URL_API_STREAM: Final = "/api/stream"
+URL_API_CORE_STATE: Final = "/api/core/state"
 URL_API_CONFIG: Final = "/api/config"
 URL_API_STATES: Final = "/api/states"
 URL_API_STATES_ENTITY: Final = "/api/states/{}"

tests/components/api/test_init.py

@@ -678,3 +678,19 @@ async def test_api_call_service_bad_data(
         "/api/services/test_domain/test_service", json={"hello": 5}
     )
     assert resp.status == HTTPStatus.BAD_REQUEST
+
+
+async def test_api_status(hass: HomeAssistant, mock_api_client: TestClient) -> None:
+    """Test getting the api status."""
+    resp = await mock_api_client.get("/api/")
+    assert resp.status == HTTPStatus.OK
+    json = await resp.json()
+    assert json["message"] == "API running."
+
+
+async def test_api_core_state(hass: HomeAssistant, mock_api_client: TestClient) -> None:
+    """Test getting core status."""
+    resp = await mock_api_client.get("/api/core/state")
+    assert resp.status == HTTPStatus.OK
+    json = await resp.json()
+    assert json["state"] == "RUNNING"