Make OTP installation optional

[michallepicki]

Currently the otp-version argument is required. In some scenarios (e.g. when using custom OTP build from a different source, or compiling Javascript with Gleam, or only creating a Gleam project without running it etc), the action could still be useful - e.g. to install Elixir or Gleam.

Would it make sense to make the otp-version argument optional, similarly to other versions?

[starbelly]

Anything is possible of course 😁 I suppose if we made it optional, then we would simply opt to grab a build against the latest stable version of OTP. Thus, if you said elixir 1.13.1 as an example, we would grab whatever the latest OTP 24 build for that version of elixir is. Is that the idea here?

[michallepicki]

@starbelly If otp_version is not provided, the OTP would not be installed (assuming it already is installed, or is not needed). Does it make sense?

Alternatively it could be a otp_version: false setting

[paulo-ferraz-oliveira]

Alternatively it could be a otp_version: false setting

If we're to update anything, I'd probably go with this approach (a compulsory input). No default: we want it explicit that the action doesn't require OTP (which is the base for all the building process, as it stands).

@starbelly, thoughts?

[starbelly]

I'd be ok with it, but here's the rub as FYI for others. We won't know what build of elixir to grab. A docker image, as an example may contain an incompatible version of OTP from what we grab for elixir. This might not be the case with gleam though?

If it's an option specific to gleam we might want to keep it that way, but for elixir it makes it all quite non-deterministic, such that people might use this option (or lack thereof), run into issues, open up issues here, etc.

Of course having a gleam specific option could be a tad confusing, I'm not against it, but it would need to be documented loudly.

[michallepicki]

I didn't think of that. So it would be really a gleam-only feature, only for some use-cases of Gleam, and introducing a bit of complexity.

If you decide not to introduce this feature, Gleam still has an option to un-archive and keep maintaining gleam-lang/setup-gleam :)

[paulo-ferraz-oliveira]

If it's an option specific to gleam we might want to keep it that way, but for elixir it makes it all quite non-deterministic, such that people might use this option (or lack thereof), run into issues, open up issues here, etc.

This is what I'm afraid of, and also the cost of "more options" (though in this very specific case the number isn't increasing, just the change of error 😄). They come at a price! But this is also why I referred, if we're to implement this, we need to make sure the option is visible (eg. with a false as proposed by @michallepicki). As it stands, there's no version relation between OTP and Gleam, as there is for OTP and Elixir, but that's because that relation is kept outside the scope of this action.

So, at the most I'd say we could allow for otp-version: false iff gleam-version is defined, for now. Would that suit everybody? I mean, if we run into trouble there's always the possibility to rollback and/or search for alternatives.

[starbelly]

I'm fine with it.

[paulo-ferraz-oliveira]

@michallepicki, we're accepting a pull request for this, then 😄, according to the previous discussion. Either that or wait for a while before I have time to tackle this.

[michallepicki]

@paulo-ferraz-oliveira Thanks! I will try to hack it together and I'll report back in a few days.