Add action typing

[Vampire]

I would like to see your action first-class supported by https://github.com/typesafegithub/github-workflows-kt, a Kotlin DSL to write GitHub Action workflows.

The project came up with ways to reduce operational load when keeping the library's action wrappers in sync with actions' inputs and outputs.
The solutions include onboarding https://github.com/typesafegithub/github-actions-typing.
It is as easy as adding an extra YAML file to your repository root, and (optionally) adding a simple GitHub workflow that validates this new file.
Thanks to this, the code generator in the Kotlin DSL can fetch typing info provided by you instead of them, which has a number of benefits.
It has no negative effects on current action consumers, they continue to use the action via regular GitHub API, as if the file was not there.

In this pull request, I would like to ask you if you are open to introduce such typings in your action and also provide the current state as far as I could determine it.
You would not be the first, there are already other actions using it, like e.g. my https://github.com/Vampire/setup-wsl or also Microsoft's https://github.com/microsoft/setup-msbuild.

Also "regular" users can benefit from this clear and formalized typing definition, seeing exactly what values are valid.
And as the typings are made independent from the Kotlin DSL library, also other DSL or similar consumers could use these typings in the future.

When accepting this PR and in the future maintaining the typing yourself,
please keep in mind that API are generated from these typing information.
So if you for example recognize that a type is wrong and want to change it for example from string to integer,
this would be a breaking change for such consumers and should therefore be done with a major version bump.
Backwards compatible changes like new enum options, or new inputs or outputs can of course be released in a minor version as usual.

After hopefully merging this PR it would be nice if you could cut a release soon,
so that the shiny new typings can be used right away.

[mxschmitt]

Thank you for your contribution! We don't feel comfortable promoting non-standard tooling.

[Vampire]

Totally understandable, but thanks for considering, and thanks for the awesome action, saved my ass a couple of times already. :-)
If it is only the note in the readme that bugs you, I can of course remove it.
The typing per-se is independent of any tooling and is merely a piece of documentation, just formalized in a way it can be helpful for users and tooling alike.

[dscho]

Well, this is not correct. The default is auto, which is not a Boolean value.

This actually points out a direction that I could get behind: using input types in the action.yml file. For example, the sudo input, which is currently declared thusly:

  sudo:
    description: 'If apt should be executed with sudo or without'
    required: false
    default: 'auto'

we could add the type and options attributes to define it like this instead:

  sudo:
    description: 'If apt should be executed with sudo or without'
    required: false
    default: 'auto'
    type: choice
    options:
    - auto
    - false
    - true

This would likely achieve at least most of what typesafegithub seems to aim for?

[dscho]

Oh, on second glance, it looks as if this is only for workflow_dispatch workflows, not for GitHub Actions' action.yml files (whose syntax appears to be limited to description, required, default and deprecationMessage, something that would appear unlikely to change).

[krzema12]

Right, we could model it as an enum, github-actions-typing supports it.

[Vampire]

Oh, on second glance, it looks as if this is only for workflow_dispatch workflows, not for GitHub Actions' action.yml files

Exactly, it was requested in https://github.com/orgs/community/discussions/32054 that they add native typing information, but for the time being there is no definition or support for it.

The 3rd party typing information could of course also be stored within the action file, but it was considered a better idea to have it in a separate file in case GitHub makes up their mind and supports native typing which likely would then be in the action file so that there will not be a clash of the tow approaches.

This would likely achieve at least most of what typesafegithub seems to aim for?

This could also be achieved with gat as @krzema12 said, using

sudo:
  type: enum
  allowed-values:
    - auto
    - true
    - false

if you like.

I just interpreted the situation as a three-sate boolean.
Not having anything set behaves either like true or false depending on context.
That is what you call auto.
I thought if you set a value, you will set either true or false but never explicitly auto.
But I could of course change this to enum if you like.

[dscho]

This is where I would wish for a much more powerful type declaration. RSA fingerprints have a very specific format that could totally be automatically type-checked statically, but simply saying string won't help that.

[krzema12]

github-actions-typing supports just primitive types for now.

[Vampire]

Who knows, maybe in the future there will be some support for validations, like min and max values for numbers like tmate-server-port, or regexes for strings like tmate-server-rsa-fingerprint.

This is just not defined yet.
But actually it might be a good idea, so I created a feature request for it at typesafegithub/github-actions-typing#205 :-)