Merge pull request #24817 from backstage/healthcheck-router

Healthcheck service

docs/backend-system/core-services/01-index.md

@@ -28,6 +28,7 @@ import { coreServices } from '@backstage/backend-plugin-api';
 - [Permissions Service](./permissions.md) - Permission system integration for authorization of user actions.
 - [Plugin Metadata Service](./plugin-metadata.md) - Built-in service for accessing metadata about the current plugin.
 - [Root Config Service](./root-config.md) - Access to static configuration.
+- [Root Health Service](./root-health.md) - Health check endpoints for the backend.
 - [Root Http Router Service](./root-http-router.md) - HTTP route registration for root services.
 - [Root Lifecycle Service](./root-lifecycle.md) - Registration of backend startup and shutdown lifecycle hooks.
 - [Root Logger Service](./root-logger.md) - Root-level logging.

docs/backend-system/core-services/root-health.md

@@ -0,0 +1,40 @@
+---
+id: root-health
+title: Root Health Service
+sidebar_label: Health
+description: Documentation for the Health service
+---
+
+The Root Health service provides some health check endpoints for the backend. By default, the `rootHttpRouter` exposes a `/.backstage/health/v1/readiness` and `/.backstage/health/v1/liveness` endpoints, which return a JSON object with the status of the backend services according the implementation of the Root Health Service.
+
+## Configuring the service
+
+The following example shows how you can override the root health service implementation.
+
+```ts
+import { RootHealthService, coreServices } from '@backstage/backend-plugin-api';
+
+const backend = createBackend();
+
+class MyRootHealthService implements RootHealthService {
+  async getLiveness() {
+    // provide your own implementation
+    return { status: 200, payload: { status: 'ok' } };
+  }
+
+  async getReadiness() {
+    // provide your own implementation
+    return { status: 200, payload: { status: 'ok' } };
+  }
+}
+
+backend.add(
+  createServiceFactory({
+    service: coreServices.rootHealth,
+    deps: {},
+    async factory({}) {
+      return new MyRootHealthService();
+    },
+  }),
+);
+```