Automatically enable web builds in forks

[wjt]

Currently after forking this repo you have to take two steps to enable web builds:

1. Go to Settings → Pages, and set the source to GitHub Actions
2. Go to Actions and allow actions to run in the fork

We may be able to automate the first one. amalgamate-pages already checks whether Pages is configured correctly:

https://github.com/endlessm/amalgamate-pages/blob/d1b9a5f9311c766c99b187bfdf6c58fef0725c24/action.yml#L13-L23

Maybe we can make it change the setting itself! (And if not we could make that step cause the rest of the workflow to be skipped rather than failing – someone was sad that it was failing and didn't click through to see why.)

We can't automate enabling actions from the workflow, by definition, but we may be able to do this in the magic script (which lives in a private repo unfortunately) which we use to clone the project board. It already does some other repo configuration such as enabling issues.

[wjt]

Unfortunately the first one can't be automated from a GitHub Actions workflow either. The POST and PUT verbs for the pages configuration require a token with "Administration" write repository permissions but you cannot grant this permission in a workflow without manually configuring your own fine-grained access token as a repo secret (which is harder than enabling Pages by hand).

OK, I think we will have to put both steps into the magic tool.

[wjt]

It is not immediately obvious if there is an API that is equivalent to this big green button:

Some discussion threads:

• https://github.com/orgs/community/discussions/104281
• https://github.com/orgs/community/discussions/40727

[wjt]

If I GET /repos/willbrushtestwood/threadbare/actions/permissions for a test fork I just created, the response is:

{
  "enabled": true,
  "allowed_actions": "all"
}

But they are not enabled. POST to that URL (to try to set enabled to true but harder) gives me 404.

OK, we will have to continue to tell mentors/contributors to enable Actions.

[wjt]

Now I am looking at configuring GitHub Pages automatically. I have some code that I think should work, but I don't think the app has the necessary permissions:

    data: {
      message: 'Resource not accessible by integration',
      documentation_url: 'https://docs.github.com/rest/pages/pages#create-a-apiname-pages-site',
      status: '403'
    }

I will follow up with the relevant team within Endless Access.