Explicitly checkout to PR commit

[ydshieh]

Allow passing commit sha of the package, so we can checkout to it.

This is necessary when we want to trigger doc-build on a PR with other trigger event, like leaving a comment build-doc, otherwise it will checkout to the main branch in this case

[ydshieh]

we checkout to the merge commit (this is what we get if the event is pull_request without the change in this PR, so the behavior would be consistent in both event types)

[gante]

LGTM

question: wouldn't ref: ${{ inputs.commit_sha }} on L81 work as well?

[gante]

(tagged @hanouticelina for a second pair of 👀 )

[ydshieh]

You are likely right. The nit is:

in the caller (the workflow I created in transformers), we have

.github/workflows/pr_build_doc_with_comment.yml

    uses: huggingface/doc-builder/.github/workflows/build_pr_documentation.yml
        commit_sha: ${{ needs.get-pr-info.outputs.PR_HEAD_SHA }}

which is the head sha of the branch, and that corresponds to

.github/workflows/build_pr_documentation.yml

    uses: huggingface/doc-builder/.github/workflows/build_pr_documentation.yml@main
    with:
      commit_sha: ${{ github.event.pull_request.head.sha }}

that also use the same head sha.

However, arriving doc-builder, in the file .github/workflows/build_pr_documentation.yml

If we use ref: ${{ inputs.commit_sha }}, it will checkout to the PR head sha.

However, currently (without this PR), it will checkout to the so called merge commit sha (when it is triggered by pull_request).
This is the usual way that Github Actions works: it doesn't directly use the head sha, but dynamically create a ``
merge commit.

So we want to:

• follow what Github Actions does things (use merge commit sha)
• follow what we have before (i.e. the doc is built with merge commit sha)

And if we don't grab this merge commit sha from the caller (which is extra work), the step I added is necessary

[hanouticelina]

Conceptually approving ✅
my understanding of the PR: the extra step makes sure that no matter how the doc build is triggered, it always checks out the correct PR merge. That makes sense to me!

[gante]

@ydshieh thank you for the detailed explanation 💛