How to ensure an Express app closes and releases the port when your process dies?

I'm using nodemon to run my Express server in development and auto-restart my process whenever a file changes. When it restarts, it frequently errors with "Port 3000 is already in use".

Killing nodemon, running killall node, and then restarting nodemon fixes it temporarily. But I want to fix it properly, and make sure the port gets released every time the app gets killed.

I've tried using signal-exit to manually call server.close() as a cleanup job:

const onExit = require('signal-exit')

onExit(() => {
  server.close();
});

But that doesn't work either. It still frequently fails to release the port. Any ideas?

via callum