Do moon repo offer concurrency?

[diraneyya]

Hey all 👋

As we continue to adopt moon as the official monorepo tool my in my full-stack development cohort, we ran into an issue using the concurrently package.

Not to use strong language, but a package such as concurrently should not exist, rather, a decent task runner should instead offer this functionality (let me know what you think of this).

Motivated by an error using concurrently (in which the commands tsc and nodemon were not found) me and my students decided to aim for using moon itself for concurrent execution. As it turns out, this is very easily and beautifully done using:

moon run server:dev-tsc server:dev-nodemon

We also liked the consistency of the output formatting, compared to the [0] and [1] markers of concurrently, all achieved without any configuration.

However, we weren't so sure as we went from there to investigating the right way to enter the concurrent task into the tasks file in moon, allowing us to invoke the above using the following command:

moon run server:dev

Doing so we tried using a noop command with the deps property and using the task references of ~:dev-tsc and ~:dev-nodemon. It was a clean syntax and we hoped it would work, but it did not.

My understanding is that the deps property is intended for build dependencies and not for concurrent execution, hence it is likely that one of the watching command was blocking the rest of the pipeline.

As a result we ended up using the following:

tasks:
  dev:
    command: "moon run server:dev-tsc server:dev-nodemon"

I do not like this for a few reasons. The one thing that stands out the most is the use of the redundant scope of server instead of self ~. The other thing is mentioning the moon command itself, which also seems redundant.

I am posting to see what you think of this, if there is a better way to achieve the same, and hopefully have more fun and constructive discussions around this and related wishes of a modern task runner.

[milesj]

Hey @diraneyya,

Great question. A noop command with deps is our go to solution for this at the moment, here's an example: https://moonrepo.dev/docs/cheat-sheet#run-multiple-watchersservers-in-parallel

You mentioned you tried this. Can you talk about why it didn't work? It should theoretically be the same as moon run server:dev-tsc server:dev-nodemon.

[diraneyya]

Thank you for the reply!

I tested it again and it indeed works 🙈 I am not sure why my earlier test showed the opposite. Apologies!

I like this syntax much better, but the output of the dependencies seem to be suppressed.

In an attempt to reproduce the same output as with moon run server:dev-tsc server:dev-nodemon I used the following (which did not work):

  dev:
    command: "noop"
    deps:
      - "~:dev-tsc"
      - "~:dev-nodemon"
    options:
      outputStyle: 'stream'

Is there a way to produce similar output from the dependencies as the case is when running multiple tasks?

[milesj]

@diraneyya Are you saying the output of dev-tsc and dev-nodemon are not showing? Or the deps of those deps?

Be sure you're dev-* tasks have local: true or the outputStyle option set. outputStyle only applies to the current task and not its deps.

[diraneyya]

Oh I see! I got to reading the following, which clarified things to me:

I did not realise that by switching the task's name from dev to dev-tsc or dev-nodemon that I was implicitly affecting the outputStyle setting, implied by the local setting 🤯🙈🤓

I have explicitly specified the outputStyle of both constituent tasks to 'stream' and now I can see the output from the dependencies. And yes it makes sense that outputStyle and other options apply to the task itself, rather than its dependencies.

Thank you!

[milesj]

Awesome, glad it works 👍