angularserver-side-renderingpm2angular19

Is Angular 19.0 incompatible with pm2?

I can't get pm2 to work with a fresh Angular 19.0 build.

Here's what I’ve tried:

The node server is not listening on any port. The process appears online in pm2, but it doesn't log anything.

When I launch the server directly using node dist/server/server.mjs, the server starts up and runs as expected. If I downgrade to angular 18.2, the server runs as usual with pm2.

Environment:

I have no clue what's happening since the logs are empty. How can I debug this?

Solution

  • I'll answer my own question as I figured it out. In the default generated server.ts file when creating a new app, the following lines appear at the end of the file:

    /**
 * Start the server if this module is the main entry point.
 * The server listens on the port defined by the `PORT` environment variable, or defaults to 4000.
 */
if (isMainModule(import.meta.url)) {
  const port = process.env['PORT'] || 4000;
  app.listen(port, () => {
    console.log(`Node Express server listening on http://localhost:${port}`);
  });
}

    The isMainModule function comes from the @angular/ssr package and "Determines whether the provided URL represents the main entry point module." However, PM2 uses a container around the Node process to manage it (see pm2/lib/ProcessContainerFork.js). As a result, the function failed to determine that it's the main module who call it, the condition is never met, and the process stops there.