GitHub reusable workflow: use latest commit

Question

I'm setting up a reusable workflow using GitHub actions: https://docs.github.com/en/actions/learn-github-actions/reusing-workflows

Since the calling workflow and called workflow are both in the same repo, I want to reference the latest commit of the called workflow inside my calling workflow's uses statement.

Example:

uses: owner/repo/.github/workflows/called-workflow.yml@${{GITHUB_SHA}}

That ${{GITHUB_SHA}} doesn't get interpolated, so I get the following error:

Invalid workflow file : .github/workflows/calling-workflow.yml#L1
handling usage of workflow "owner/repo/.github/workflows/called-workflow.yml@${{GITHUB_SHA}}": can't obtain workflow file: reference to workflow should be either a valid branch, tag, or commit

How can I set the ref to the latest commit when calling a workflow within a workflow?

Answer 1

This is now possible

As of February 2022.

First in January: https://github.blog/changelog/2022-01-25-github-actions-reusable-workflows-can-be-referenced-locally/

Up until today-ish though (2022-Feb-10), there was a bug that prevented it from working on pull_request events; that has now been fixed: https://github.community/t/ref-head-in-reusable-workflows/203690/74?u=briantist

Example usage:

jobs:
  call-workflow-in-local-repo:
    uses: ./.github/workflows/workflow-2.yml