set associated head sha on pull request event

[crazy-max]

fixes #206

Signed-off-by: CrazyMax [email protected]

[gustavovalverde]

This might seem as a fix in versioning, but it's a breaking change. For example, this breaks all our workflows which depend on the built image sha

Now we have to include extra conditions as the sha won't be the same when there's a PR and a push to main. It would have been nice to increase the version to 5.0.0 considering this would break most scenarios being based on GITHUB_SHA or ${{ github.sha }}

This now requires implementations to use ( ${{ github.event.pull_request.head.sha }} || {{ github.sha }} ) for a single pull to work on both GitHub events (PRs and push)

[crazy-max]

@gustavovalverde From what I see on ZcashFoundation/zebra#5390, you're pushing an image on PR and others jobs depend on it using github.sha as tag.

I didn't think about this use case as pushing on PR is not possible in majority of cases as secrets can't be exposed. But in your case I see you're using google-github-actions/auth action to connect to your provider using the OIDC token so you're able to push to its registry.

Even if you can share image between jobs without pushing them, it still sounds like a valid use case to use a registry. I will revert this change, sorry about that.

[dimaqq]

This appears to check that substring “pull_request” appears anywhere in the event name. Maybe the intention was to check if the name starts with a certain substring? Or matches exactly if that’s the entire event name?