Github composite action output can not be set from within a bash script

Question

For one of my projects, I am setting an action output from within a bash script that is executed inside a composite action. I found that GitHub has excellent documentation on how to create a GitHub composite action output. It states that this can be done using the following action.yml file.

name: 'Hello World'
description: 'Greet someone'
inputs:
  who-to-greet:  # id of input
    description: 'Who to greet'
    required: true
    default: 'World'
outputs:
  random-number:
    description: "Random number"
    value: ${{ steps.random-number-generator.outputs.random-number }}
runs:
  using: "composite"
  steps:
    - run: echo Hello ${{ inputs.who-to-greet }}.
      shell: bash
    - id: random-number-generator
      run: echo "random-number=$(echo $RANDOM)" >> $GITHUB_OUTPUT
      shell: bash
    - run: echo "${{ github.action_path }}" >> $GITHUB_PATH
      shell: bash
    - run: goodbye.sh
      shell: bash

I checked the results using the following action workflow, and it works.

on: [push]

jobs:
  hello_world_job:
    runs-on: ubuntu-latest
    name: A job to say hello
    steps:
      - uses: actions/checkout@v3
      - id: foo
        uses: actions/hello-world-composite-action@v1
        with:
          who-to-greet: 'Mona the Octocat'
      - run: echo random-number ${{ steps.foo.outputs.random-number }}
        shell: bash

My use case, however, differs from the example above in that I have to set the output variable inside the goodbye.sh script. According to the documentation, this should be done using the GITHUB_OUTPUT variable:

echo "{name}={value}" >> $GITHUB_OUTPUT

After some testing, this method is not working for composite actions. As this could also be a bug or not supported, I created a bug report at https://github.com/orgs/community/discussions/47775. However, I quickly wanted to double-check if there may be something wrong with my syntax.

Steps to reproduce

1. Fork this repository.
2. Enable GitHub actions on the fork.
3. Push a commit to your fork.
4. See that only the random-number variable is set while the random-number-bash` is set (See this example workflow).

Answer 1

I found my issue using @benjamin-w's comment. The problem was that the goodbye.sh step should contain an id key for the created output to be referenced correctly. The correct syntax should be:

action.yml

name: 'Hello World'
description: 'Greet someone'
inputs:
  who-to-greet:  # id of input
    description: 'Who to greet'
    required: true
    default: 'World'
outputs:
  random-number:
    description: "Random number"
    value: ${{ steps.random-number-generator.outputs.random-number }}
  random-number-bash:
    description: "Random number bash"
    value: ${{ steps.random-number-generator-bash.outputs.random-number-bash }}
runs:
  using: "composite"
  steps:
    - run: echo Hello ${{ inputs.who-to-greet }}.
      shell: bash
    - id: random-number-generator
      run: echo "random-number=$(echo $RANDOM)" >> $GITHUB_OUTPUT
      shell: bash
    - run: echo "${{ github.action_path }}" >> $GITHUB_PATH
      shell: bash
    - run: goodbye.sh
      id: random-number-generator-bash
      shell: bash

And the correct syntax for creating the output in the goodbye.sh script should be:

Goodbye.sh

echo "Goodbye"
echo "random-number-bash=$(echo 123)" >> $GITHUB_OUTPUT

Which then can be tested using the following workflow file:

Test workflow

on: [push]

jobs:
  hello_world_job:
    runs-on: ubuntu-latest
    name: A job to say hello
    steps:
      - uses: actions/checkout@v3
      - id: foo
        uses: rickstaa/hello-world-composite-action-output-bug@main
        with:
          who-to-greet: 'Mona the Octocat'
      - run: echo random-number ${{ steps.foo.outputs.random-number }}
        shell: bash
      - run: echo random-number ${{ steps.foo.outputs.random-number-bash }}
        shell: bash