I need to run a workflow when a Pull Request closes, and it depends on the SHA of the most recent commit before the pull request was closed. However, when looking into ways to do that, I’ve found that $GITHUB_SHA did not, in fact, have that - instead, I could only find it by grabbing it from the github context, in the path github.event.pull_request.head.sha.

These are my results from running these two commands in my action:

      - name: sha from context
        run: echo ${{ github.event.pull_request.head.sha }}
  - name: sha from env var
    run: echo $GITHUB_SHA

image851×410 35.1 KB

As you can see, what I get from $GITHUB_SHA does not match the hash displayed under the commit message. Why are these two different?