How do you design a graceful shutdown mechanism in a Node.js app when receiving SIGTERM or SIGINT signals?

Short answer

Intercept the signal, stop accepting new requests through server.close(), wait for in-flight requests to finish, close the database connections, then exit with process.exit(0).

Explanation

In cloud container environments, the system sends a SIGTERM signal to give the app a chance to shut down cleanly. The correct steps include stopping the server, setting a maximum timeout in case any requests hang, closing database connection pools and WebSocket sockets, then exiting with the success code 0.

Code example

process.on("SIGTERM", async () => {
  server.close(async () => {
    await db.close();
    process.exit(0);
  });
});

Common mistakes

• Not setting a forced timeout in case there is a stuck request or an endlessly open connection.

Follow-up questions

• What is the difference between uncaughtException and unhandledRejection in Node.js and what is the right action when they occur?

Sources

• Node.js docs — process: Signal events