PRs from forks break - Githubissues

After applying the centralized CI to pyiron_contrib, the dependabot PRs revealed that the current automated update to docs and binder environment files breaks for third-party PRs, e.g.:

Run actions/checkout@v3
  with:
    ref: dependabot/pip/scikit-image-0.21.0
    fetch-depth: 0
    repository: pyiron/pyiron_contrib
    ssh-strict: true
    persist-credentials: true
    clean: true
    lfs: false
    submodules: false
    set-safe-directory: true
Error: Input required and not supplied: token

Going back and re-reading the security docs confirmed our suspicion that the secrets are not getting passed nor is write permission available from external forks using on: pull_request. We do get these powers in the dependabot PR because that is explicitly on: pull_request_target.

So before pyiron_contrib was on the centralized CI, the only place that got third-party write access and secrets was the dependabot workflow. Now, under the centralized CI we are expecting these privileges in the main on: pull_request workflow in order to keep the docs/environment.yml and .binder/environment.yml files synchronized with .ci_support/environment.yml (plus the extra stuff we need for docs/notebooks).

The advantage to the centralized CI way is that we never need to modify the docs and binder environments, they are just always kept up-to-date.

One solution:

Add this environment update to the dependabot update on: pull_request_target script
- With the same actor filtering we have for the existing environment update providing security
- Now dependabot will propagate its environment updates through to the other env files
Filter this environment update step to only happen on PRs originating from pyiron
- Non-dependabot forks may possibly result in the docs and binder envs getting out-of-date
- This will be fixed automatically on the next PR from either pyiron or dependabot
- Dependabot will not be double-propagating the changes, since it gets filtered out here
Remove the needs: commit-updated-env from the rest of the CI steps in the main push-pull workflow
- These were here for efficiency, since the other steps would sometimes start, then get killed and restarted when there was a commit to update the envs, so we're very slightly wasteful by removing this.

Then dependabot can update all the env files it needs to, the dependent env-files stay (almost always) up-to-date, and the rest of the CI is free to run even on third-party PRs.

If you like it, I'll take care of implementation, but I wanted to solicit feedback on the plan first.

pyiron / actions

PRs from forks break #44