Send Message Via Nodemon

[nahtnam]

• nodemon -v:1.18.9
• node -v:10.14.2
• Operating system/terminal environment: MacOS High Sierra
• Using Docker? What image: No
• Command you ran: Used required version of nodemon

So I have a weird/interesting use case of nodemon. I want to conditionally restart the server (which is possible), however the times I don't want to restart the server, I would like to send a message/event to the child process/instance of my code.

Expected behaviour

I have looked at the docs and skimmed through the source code, I don't think its possible.

Actual behaviour

Nothing happens

Steps to reproduce

Here is the code I use:

const server = nodemon({
  watch: ['src'],
  ext, // assume .js
  ignore: [path.join(cwd, `./src/routes/**/*.${ext}`)], // i am excluding this folder so I can conditionally restart
  exec, // node src/index.js
});

// this is fine
server.on('start', function () {
  console.log('nodemon started');
}).on('crash', function () {
  console.log('script crashed for some reason');
}).on('restart', () => {
  console.log('nodemon is restarting')
})

chokidar.watch(
  path.join(cwd, './src/routes', `**/*.js`),
  {
    ignored: /(^|[\/\\])\../, // ignore dot files
  }
).on('change', (path) => {
  if (something) {
    nodemon.restart(); // great
  } else {
    nodemon.send('message', 'dont restart but do this'); // UNIMPLEMENTED/HOW DO I DO THIS?
  }
});

One possible solution is to give access to the child_process that nodemon opens up.

---

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[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3

[nahtnam]

Bump!

[remy]

By "send message" - can you be more specific? What exactly do you want to send?

[nahtnam]

@remy Kind of like emitting events to a child process. https://medium.com/@NorbertdeLangen/communicating-between-nodejs-processes-4e68be42b917 Something like this but the events should go to my server such that I can tell it to hot swap the module instead of restarting

[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3

[nahtnam]

Bump!

[nahtnam]

@remy Any thoughts on this issue?

[remy]

Your original reply didn't really answer my question.

nodemon.send('message', 'dont restart but do this'); // UNIMPLEMENTED/HOW DO I DO THIS?

nodemon supports postMessage for RPC, but your slim example is two things: 1) don't restart, 2) "this"

What is "this" supposed to be. Can you provide an example of exactly what you would like to do?

[nahtnam]

@remy

Sorry for the late response. So here is my use case: I am working on a "framework"/library for my app where it will hot-swap certain modules so the server doesn't have to restart (boot-time is a few seconds) only in development mode. I would however like to use nodemon to restart the server if any of the files that are not in that specific folder change.

Here is how I start the server in my CLI program:

const server = nodemon({
  watch: ['src'],
  ext, // assume .js
  ignore: [path.join(cwd, `./src/routes/**/*.${ext}`)], // i am excluding this folder so I can conditionally restart
  exec: 'node src/index.js',
});

Notice how I ignore the routes folder. I then set up chokidar to watch the routes folder manually:

chokidar.watch(
  path.join(cwd, './src/routes', `**/*.js`),
  {
    ignored: /(^|[\/\\])\../, // ignore dot files
  }
).on('change', (path) => {
  if (shouldFullyRestartServer) {
    nodemon.restart(); // great
  } else {
    # HERE
  }
});

Where it says HERE, I want to tell the child process which is running node src/index.js to emit a "swapModule" event or something which would trigger the child app to swap out the modules.

Maybe there is a simpler solution that I can't see, but basically, I would like the ability for the parent process running nodemon via script to be able to send messages to the child process that nodemon starts.

Thanks!

[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3

[remy]

Okay, I can follow your code example. You want to push the message directly into the child but it needs to go via nodemon. I think I can see how that would work.

I'll have to come back to you (though the stalebot will keep trying to close this issue - sorry!)

[nahtnam]

Hey!

Thank you! I think the opposite should also work (and I might need it for that specific use case). If the child emits an event, nodemon could capture it and add a "event" hook or something that the parent can listen on.

Thanks,
@nahtnam

[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3

[nahtnam]

bump!

[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3

[nahtnam]

Bump (because it looks like there is some progress being made).

Unfortunately I don't need this feature anymore (I ended up with a better solution) but hopefully, someone finds this useful. Thank you!

[stale]

This issue has been automatically marked as idle and stale because it hasn't had any recent activity. It will be automtically closed if no further activity occurs. If you think this is wrong, or the problem still persists, just pop a reply in the comments and @remy will (try!) to follow up.
Thank you for contributing <3