feat(core): Introduce DB health check

packages/cli/src/abstract-server.ts

@@ -119,11 +119,17 @@ export abstract class AbstractServer {
 	protected setupPushServer() {}
 
 	private async setupHealthCheck() {
-		// health check should not care about DB connections
+		// main health check should not care about DB connections
 		this.app.get('/healthz', async (_req, res) => {
 			res.send({ status: 'ok' });
 		});
 
+		this.app.get('/healthz/readiness', async (_req, res) => {
+			return Db.connectionState.connected && Db.connectionState.migrated
+				? res.status(200).send({ status: 'ok' })
+				: res.status(503).send({ status: 'error' });
+		});
+
 		const { connectionState } = Db;
 		this.app.use((_req, res, next) => {
 			if (connectionState.connected) {

packages/cli/src/commands/worker.ts

@@ -172,6 +172,12 @@ export class Worker extends BaseCommand {
 
 		const server = http.createServer(app);
 
+		app.get('/healthz/readiness', async (_req, res) => {
+			return Db.connectionState.connected && Db.connectionState.migrated
+				? res.status(200).send({ status: 'ok' })
+				: res.status(503).send({ status: 'error' });
+		});
+
 		app.get(
 			'/healthz',
 

packages/cli/test/integration/healthcheck.controller.test.ts

@@ -0,0 +1,22 @@
+import * as testDb from './shared/test-db';
+import { setupTestServer } from '@test-integration/utils';
+
+const testServer = setupTestServer({ endpointGroups: ['health'] });
+
+describe('HealthcheckController', () => {
+	it('should return ok when DB is connected and migrated', async () => {
+		const response = await testServer.restlessAgent.get('/healthz/readiness');
+
+		expect(response.statusCode).toBe(200);
+		expect(response.body).toEqual({ status: 'ok' });
+	});
+
+	it('should return error when DB is not connected', async () => {
+		await testDb.terminate();
+
+		const response = await testServer.restlessAgent.get('/healthz/readiness');
+
+		expect(response.statusCode).toBe(503);
+		expect(response.body).toEqual({ status: 'error' });
+	});
+});

packages/cli/test/integration/shared/test-db.ts

@@ -39,11 +39,16 @@ export async function init() {
 	await Db.migrate();
 }
 
+export function isReady() {
+	return Db.connectionState.connected && Db.connectionState.migrated;
+}
+
 /**
  * Drop test DB, closing bootstrap connection if existing.
  */
 export async function terminate() {
 	await Db.close();
+	Db.connectionState.connected = false;
 }
 
 // Can't use `Object.keys(entities)` here because some entities have a `Entity` suffix, while the repositories don't

packages/cli/test/integration/shared/types.ts

@@ -10,6 +10,7 @@ import type { LicenseMocker } from './license';
 import type { Project } from '@/databases/entities/project';
 
 type EndpointGroup =
+	| 'health'
 	| 'me'
 	| 'users'
 	| 'auth'
@@ -54,6 +55,7 @@ export interface TestServer {
 	authAgentFor: (user: User) => TestAgent;
 	publicApiAgentFor: (user: User) => TestAgent;
 	authlessAgent: TestAgent;
+	restlessAgent: TestAgent;
 	license: LicenseMocker;
 }
 

packages/cli/test/integration/shared/utils/test-server.ts

@@ -44,9 +44,16 @@ function prefix(pathSegment: string) {
 }
 
 const browserId = 'test-browser-id';
-function createAgent(app: express.Application, options?: { auth: boolean; user: User }) {
+function createAgent(
+	app: express.Application,
+	options?: { auth: boolean; user?: User; noRest?: boolean },
+) {
 	const agent = request.agent(app);
-	void agent.use(prefix(REST_PATH_SEGMENT));
+
+	const withRestSegment = !options?.noRest;
+
+	if (withRestSegment) void agent.use(prefix(REST_PATH_SEGMENT));
+
 	if (options?.auth && options?.user) {
 		const token = Container.get(AuthService).issueJWT(options.user, browserId);
 		agent.jar.setCookie(`${AUTH_COOKIE_NAME}=${token}`);
@@ -89,6 +96,7 @@ export const setupTestServer = ({
 		httpServer: app.listen(0),
 		authAgentFor: (user: User) => createAgent(app, { auth: true, user }),
 		authlessAgent: createAgent(app),
+		restlessAgent: createAgent(app, { auth: false, noRest: true }),
 		publicApiAgentFor: (user) => publicApiAgent(app, { user }),
 		license: new LicenseMocker(),
 	};
@@ -119,6 +127,13 @@ export const setupTestServer = ({
 			app.use(...apiRouters);
 		}
 
+		if (endpointGroups?.includes('health')) {
+			app.get('/healthz/readiness', async (_req, res) => {
+				testDb.isReady()
+					? res.status(200).send({ status: 'ok' })
+					: res.status(503).send({ status: 'error' });
+			});
+		}
 		if (endpointGroups.length) {
 			for (const group of endpointGroups) {
 				switch (group) {