Get Github action output from previous step

Question

I am building my own Github-actions repository. I am trying to use the output of an action in the following step, but I could not manage to do so.

This is a minimal example with what I want to do:

I have an action that do some stuff and stores an output value (boolean for instance). The minimum action.yml would be like this:

# action_with_output/action.yml
name: action_with_output

outputs:
  out:
    description: 'Some output'

runs:
  using: composite
  steps:
    - name: action with output step
      shell: bash
      run: echo "out=true" >> $GITHUB_OUTPUT

Then, in my workflow I want to use such output called out. Like this:

# .github/workflows/my_workflow.yml
...

workflow_name:
  runs-on: ubuntu-22.04
  steps:

  - name: Sync repository
    uses: actions/checkout@v3
    with:
      path: src

  - name: Run some action with output
    uses: ./src/action_with_output
    id: step1

  - name: Read output
    run: echo "${{ steps.step1.outputs.out }}"

I would expect the output of step Read output to be true, but instead I do not get any output, as if the output variable never existed.

---

You can see some test cases in this PR: https://github.com/eProsima/eProsima-CI/actions/runs/4945870294/jobs/8843185789?pr=26

---

It works if I try the same but instead of calling the action action_with_output, I use this step:

  - name: Run some action with output
    run: echo "out=true" >> $GITHUB_OUTPUT
    id: step1

Answer 1

Okey, I just figured out what I missed with this answer: https://stackoverflow.com/a/64471887/17049427

I have to explicitly specify the value of each output variable as follows:

# action_with_output/action.yml
name: action_with_output

outputs:
  out:
    description: 'Some output'
    value: ${{ steps.run.outputs.out }}

runs:
  using: composite
  steps:
    - name: action with output step
      id: run
      shell: bash
      run: echo "out=true" >> $GITHUB_OUTPUT