Make GitHubTagProvider server URL configurable to enable mock testing

[LalatenduMohanty]

Problem

GitHubTagProvider hardcodes its API endpoint as a class variable:

host = "github.com:443"
api_url = "https://api.{self.host}/repos/{self.organization}/{self.repo}/tags"

This can't be overridden per-instance, so every use hits the real GitHub API. In CI, fork PRs can't use GITHUB_TOKEN (GitHub security restriction), leaving tests subject to the shared 60 req/hr unauthenticated rate limit.

GitLabTagProvider already supports this — it accepts a server_url constructor parameter.

Proposed Solution

1. Add a server_url parameter to GitHubTagProvider.__init__(), defaulting to https://api.github.com. Derive api_url from it, matching the GitLab pattern.

2. Update the stevedore_github.py e2e plugin to accept a mock URL (e.g. via env var).

3. Update test_bootstrap_cooldown_github.sh to start a local HTTP server serving static tag JSON, using the existing local server pattern from e2e/common.sh.

This eliminates ~16 GitHub API calls per CI run (4 paginated pages × 4 parallel ci_bootstrap_suite jobs) and makes the test deterministic regardless of GitHub API availability.

Context

• Rate limiting:
  • Fail fast on GitHub API rate limit instead of hanging for 25+ minutes #1118
  • PR tests: pass GITHUB_TOKEN to tests #1117
• Fork PRs cannot use GITHUB_TOKEN, so mocking is the only reliable fix for CI
• GitLabTagProvider already has server_url parameter — this brings parity

Files

• src/fromager/resolver.py — GitHubTagProvider
• e2e/github_override_example/src/package_plugins/stevedore_github.py
• e2e/test_bootstrap_cooldown_github.sh

[tiran]

Questions:

• Do forks get no GitHub token at all or is the GitHub token of personal forks limited and scoped to the fork?
• Is the issue worth the additional code and less realistic tests? It's the first time I noticed the delay due to rate limiting.

[tiran]

#1122 is a PR from my personal fork. It shows that jobs from a fork have access to a valid GitHub token.

      - name: Show github token
        run: gh auth status
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Run gh auth status
github.com
  ✓ Logged in to github.com account github-actions[bot] (GITHUB_TOKEN)
  - Active account: true
  - Git operations protocol: https
  - Token: ghs_************************************

[LalatenduMohanty]

I was under the impression that token are not accessible to forks. Fork PRs have a read-only GITHUB_TOKEN (confirmed in #1122), giving 5,000 req/hr for API reads. The rate-limiting concern doesn't apply, so mocking isn't needed.

So closing the issue and the PR.