Give the server a health check

How to do it

Add an address such as /healthz that runs a cheap query against the database and other dependencies. Answer 200 when all work and 503 when one fails. Keep it fast and free of private data. The one-step deploy polls it and rolls back on failure. For more depth, see liveness and readiness.

Example

app.get('/healthz', (req, res) => {
  try {
    db.prepare('SELECT 1').get();
    res.type('text').send('ok');
  } catch {
    res.status(503).type('text').send('database unavailable');
  }
});

How to check

Stop a dependency on a test server. The health check answers 503 within a second.