make reference accessible in reusable workflow

[kagahd]

Describe the enhancement

A reusable workflow should be able to access the reference that it was called for.

Context

A reusable workflow in public repos may be called by appending a reference which can be a SHA, a release tag, or a branch name, as for example:
{owner}/{repo}/.github/workflows/{filename}@{ref}

Githubs documentation states:

When a reusable workflow is triggered by a caller workflow, the github context is always associated with the caller workflow.

The problem

Since the github context is always associated with the caller workflow, the reusable workflow cannot access the reference, for example the tag v1.0.0. However, knowing the reference is important when the reusable workflow needs to checkout the repository in order to make use of composite actions.

Code snippet

Assume that the caller workflow is being executed from within the main branch and calls the ref v1.0.0. of a reusable workflow:

name: Caller workflow
on:
  workflow_dispatch:

jobs:
  caller:
    uses: owner/public-repo/.github/workflows/reusable-workflow.yml@v1.0.0

Here is the reusable workflow that uses a composite action:

name: reusable workflows
on:
  workflow_call:

jobs:
  first-job:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3.1.0
        with:
          repository: owner/public-repo
          ref: ${{ github.ref_name }}

      - name: composite action
        uses: ./actions/my-composite-action

In the above code snippet, ${{ github.ref_name }} is main instead of v1.0.0 because github context is always associated with the caller workflow. Therefore, the composite actions code is based on main and not on v1.0.0.

Proposal

Introduce a new github context variable caller_ref which reflects the reference indicated by the caller.
The reusable workflow could then use it as follows:

name: reusable workflows
on:
  workflow_call:

jobs:
  first-job:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3.1.0
        with:
          repository: owner/public-repo
          ref: ${{ github.caller_ref }}

      - name: composite action
        uses: ./actions/my-composite-action

Or even shorter without the need to checkout:

name: reusable workflows
on:
  workflow_call:

jobs:
  first-job:
    runs-on: ubuntu-latest
    steps:
      - name: composite action
        uses: ./actions/my-composite-action@${{ github.caller_ref }}

Now, the composite action would be using v1.0.0. as indicated by the caller.

Related to this FR:

• The shared workflows reference actions as though they are external rather than in the same repository ansible-community/github-docs-build#4 (comment)
• Allow running the reusable workflow from the same branch #932

[cbrzn]

I have the same issue, and would love some help!

[carlcsaposs-canonical]

Ran into the same issue, here's a workaround: https://github.com/canonical/data-platform-workflows/blob/main/.github/workflows/_get_workflow_version.yaml

To solve this, we're now using this composite action (that implements @maxbergs's solution)

https://github.com/canonical/get-workflow-version-action

Example usage:

# Reusable workflow (e.g. build_charm.yaml)
on:
  workflow_call:

jobs:
  foo:
    runs-on: ubuntu-latest
    steps:
      - name: Get workflow version
        id: workflow-version
        uses: canonical/get-workflow-version-action@v1
        with:
          repository-name: canonical/data-platform-workflows
          file-name: build_charm.yaml
      # Use the version. For example:
      - name: Install Python CLI
        run: pipx install git+https://github.com/canonical/data-platform-workflows@'${{ steps.workflow-version.outputs.sha }}'#subdirectory=python/cli

[mjhipp]

I am also interested in a solution for this. My use case is I have a repository within my org where I put shared workflows as well as composite actions. I often want to use composite actions within my reusable workflow in the same repository.

I see that you can do this with reusable workflows, but not yet composite actions: https://github.blog/changelog/2022-01-25-github-actions-reusable-workflows-can-be-referenced-locally/

mjhipp/shared-actions
├── actions
│   └── my-composite-action
│       └── action.yml
└── workflows
    └── my-reusable-workflow.yml

name: My Reusable Workflow
on:
  workflow_call:
jobs:
  my-reusable-workflow:
    runs-on: ubuntu-latest:
    steps:
      - uses: mjhipp/shared-actions/actions/my-composite-action@{???}

I would like to use whatever version I am using for the shared workflow for the called composite action, from the same repo as the called workflow.
I could use 'main', but I like to pin version tags in my actions for safety.

[jrosend]

I'd love this new reference to be created as well. I'm facing the same problem.

[dstuck]

Presumably the github.job_workflow_sha which is "For jobs using a reusable workflow, the commit SHA for the reusable workflow file" should solve this but it appears that this variable isn't ever populated: actions/runner#2417

[GustavoKatel]

I am also interested in a solution for this. My use case is I have a repository within my org where I put shared workflows as well as composite actions. I often want to use composite actions within my reusable workflow in the same repository.

I see that you can do this with reusable workflows, but not yet composite actions: https://github.blog/changelog/2022-01-25-github-actions-reusable-workflows-can-be-referenced-locally/

mjhipp/shared-actions
├── actions
│   └── my-composite-action
│       └── action.yml
└── workflows
    └── my-reusable-workflow.yml

name: My Reusable Workflow
on:
  workflow_call:
jobs:
  my-reusable-workflow:
    runs-on: ubuntu-latest:
    steps:
      - uses: mjhipp/shared-actions/actions/my-composite-action@{???}

I would like to use whatever version I am using for the shared workflow for the called composite action, from the same repo as the called workflow. I could use 'main', but I like to pin version tags in my actions for safety.

I have the same use case and having this implemented would be great for pinning version between the reusable and the composite action

[cezar-tech]

Also having this need in my enterprise