4_composite_actions.md

Composite actions - Building (and publishing) custom actions

Extract logic from multiple actions

There are often steps which need to be repeated with different inputs. These steps can be extracted and reused, just like in software development the dry principle.

Composite action

.github/actions/extracted-step/action.yaml

name: Greet and create
description: 'Greet someone and create a random number as output'
inputs:
  who-to-greet: 
    description: 'Who to greet'
    required: true
outputs:
  random-number:
    description: "Random generated number"
    value: ${{ steps.random-number-generator.outputs.random-number }}
runs:
  using: "composite"
  steps:
    - name: Set Greeting
      run: echo "Hello $INPUT_WHO_TO_GREET."
      shell: bash
      env:
        INPUT_WHO_TO_GREET: ${{ inputs.who-to-greet }}
    - name: Random Number Generator
      id: random-number-generator
      run: echo "random-number=$(echo $RANDOM)" >> $GITHUB_OUTPUT
      shell: bash

Using composite action

.github/workflows/example.yaml

jobs:
  greet-randomize:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - id: greet-and-randomize
        uses: ./.github/actions/greet-and-randomize
        with:
          who-to-greet: 'Hack&Heat'
      - run: echo random-number "$RANDOM_NUMBER"
        shell: bash
        env:
          RANDOM_NUMBER: ${{ steps.greet-and-randomize.outputs.random-number }}

Creating complex actions

-> https://github.com/senacor/workshop-github-action-action

Integration

  greet-randomize-external:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - id: greet-and-randomize
        uses: senacor/[email protected]
        with:
          who-to-greet: 'Hack&Heat'
      - run: echo random-number "$RANDOM_NUMBER"
        shell: bash
        env:
          RANDOM_NUMBER: ${{ steps.greet-and-randomize.outputs.random-number }}