Need a callback on start of standalone server

[rajatdhoot123]

Goal

Deploy a Next.js standalone app with zero downtime by running a specific command (process.send) when the server starts.

Background

There is a need for a server start callback to facilitate various purposes, including deploying with pm2 without downtime.

Proposal

Add a callback in the finally block of the server start process to execute the desired command. Modify the existing code as follows:

startServer({
  dir,
  isDev: false,
  config: nextConfig,
  hostname,
  port: currentPort,
  allowRetry: false,
  keepAliveTimeout,
  useWorkers: true,
}).catch((err) => {
  console.error(err);
  process.exit(1);
}).finally(() => {
  nextConfig.onServerCallback();
});

This modification ensures that the specified command (nextConfig.onServerCallback()) is executed after the server starts, addressing the need for a server start callback.

[rajatdhoot123]

https://pm2.keymetrics.io/docs/usage/pm2-api/