Github actions: Workflow tricks

This is a collection of how to accomplish various tasks and tricks in github workflows, which are not directly covered by the github actions documentation and aren’t obvious.

How to query the type of an event

When you add a trigger event, for example “pull_request”, to the workflow, this event usually has more than one type. In the case of pull_request, this could be “open”, “reopened” and “synchronize”. If you only want to run a step of your workflow when the workflow was triggered by a certain event type (e.g. when a pull request was opened, but not when it receives new pushes), you can add an if-condition to the steps.

The if-condition has to query github.event.action:

on:
  workflow_dispatch:
  pull_request:
    types: [opened, closed, reopened, synchonize]

jobs:
  build:    
    name: Print info
    runs-on: ubuntu-latest
    steps:
      - name: Print GitHub event action
        run: |
          echo "${{ github.event.action }}"
      - name: Run when PR is opened
        if: ${{ github.event_name == 'pull_request' && github.event.action == 'opened' }}
        run: |
          echo "You just opened a PR!"