add restart tolerance

web/frontend/server.js

@@ -6,6 +6,12 @@ const app = express();
 app.use('/assets', express.static('build/client/assets', { immutable: true, maxAge: '1y' }));
 app.use(express.static('build/client', { maxAge: '1h' }));
 
+// Answers from Express alone so the container health check reports on this
+// process only, independent of whether the API is reachable yet.
+app.get('/healthz', (_req, res) => {
+    res.status(200).type('text/plain').send('ok');
+});
+
 const requestHandler = createRequestHandler({
     build: () => import('./build/server/index.js'),
 });