This has been discussed multiple times on this forum, here is an incomplete list of relevant topics:

• Templates for GitHub Actions?
• Reusable component composite action python version
• reusing/sharing/inheriting steps between jobs declarations
• Support for YAML anchors
• Reuse Github Actions inside other Actions?
• Is it possible to reuse workflow yaml to setup similar workflows?
• Declaratively define GitHub actions
• Common steps for all workflows?
• Executing external GitHub action from shell or JS scripts
• Allow an action which groups other actions

Thank you. Unfortunately, the documentation doesn’t state what is supported & not supported. This is the reason for the confusion.

Are there any plans to support use in composite actions? Without those, they’re just another way of writing a bash script 😦

There is some ongoing work:

  <a href="https://github.com/actions/runner/pull/1144" target="_blank" rel="noopener">github.com/actions/runner</a>

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  <code>actions:main</code> ← <code>actions:thboop/CompositeAdr</code>
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    opened <span class="discourse-local-date" data-format="ll" data-date="2021-06-10" data-time="21:41:30" data-timezone="UTC">09:41PM - 10 Jun 21 UTC</span>
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  <div class="user">
    <a href="https://github.com/thboop" target="_blank" rel="noopener">
      <img alt="thboop" src="https://user-images.githubusercontent.com/5814919/181093242-b0fa58b5-a3db-464f-ad4d-cd580cf88dc1.jpeg" class="onebox-avatar-inline" width="20" height="20">
      thboop
    </a>
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    <a href="https://github.com/actions/runner/pull/1144/files" target="_blank" rel="noopener">
      <span class="added">+94</span>
      <span class="removed">-0</span>
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I haven’t seen anything about when we can expect this to become available, though.

Shocking amounts of code duplication because this isn’t a feature

According to the Metadata Syntax documentation, under the section for "runs for composite actions," composite actions allow the use of uses. See here: Metadata syntax for GitHub Actions - GitHub Docs

Is this a recent change, or is the documentation incorrect?

If the documentation is correct and this works now, I’m still not able to get it working. I’m seeing Unexpected value 'uses' errors. (for example, here: run actions on all pushes · ramsey/composer-install@793876b · GitHub)

The documentation shows examples like this:

runs:
  using: "composite"
  steps:
    # Reference a specific commit
    - uses: actions/checkout@a81bbbf8298c0fa03ea29cdc473d45769f953675
    # Reference the major version of a release
    - uses: actions/checkout@v2
    # Reference a specific version
    - uses: actions/checkout@v2.2.0
    # Reference a branch
    - uses: actions/checkout@main
    # References a subdirectory in a public GitHub repository at a specific branch, ref, or SHA
    - uses: actions/aws/ec2@main
    # References a local action
    - uses: ./.github/actions/my-action
    # References a docker public registry action
    - uses: docker://gcr.io/cloud-builders/gradle
    # Reference a docker image published on docker hub
    - uses: docker://alpine:3.8

and this:

runs:
  using: "composite"
  steps:
    - name: My first step
      uses: actions/hello_world@main
      with:
        first_name: Mona
        middle_name: The
        last_name: Octocat  

After some trial-and-error, I got uses working with composite actions. They were failing because I was specifying working-directory. Once I removed that, they work.

Is this a recent change, or is the documentation incorrect?

Sort of recent, as in August, about one month after the last post in this thread before yours. 😉

  <a href="https://github.blog/changelog/2021-08-25-github-actions-reduce-duplication-with-action-composition/" target="_blank" rel="noopener">The GitHub Blog</a>

GitHub Actions: Reduce duplication with action composition | GitHub Changelog

GitHub Actions: Reduce duplication with action composition

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