How to trigger a GitHub action from a different GitHub action file

It is easy to run one Github action job after another by using the needs keyword.

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Run build
        run: echo "Running build steps..."

  deploy:
    needs: build
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Deploy code
        run: echo "Deploying..."

In the example above, the deploy job has a needs directive that states that deploy can only run after build has been completed successfully.

However, what about if we want an entire series of jobs in a separate GitHub action file to run after a job in a completely different file has run?

Fortunately, it is possible to create a repository dispatch event to trigger Github actions.

A repository dispatch event is an endpoint that triggers a webhook event called repository_dispatch.

Even more, fortunately, is that somebody has wrapped the finer details of triggering a repository_dispatch webhook event into an excellent GitHub action in this repo.

I faced a problem running webpage-test on a staging site only after it was successfully deployed, and I wanted the logic segregated into its own Github action file.

Below is the code that creates the dispatch event for an event I have named trigger-webpage-test-for-frontendsupport

- name: Trigger webpage test
  uses: peter-evans/repository-dispatch@v1
  with:
    token: ${{ secrets.PAT }}
    repository: dagda1/cuttingedge
    event-type: trigger-webpage-test-for-frontendsupport

The action that runs web-page-test in a different file:

name: run webpage test for frontendrescue

on:
  repository_dispatch:
    types: [trigger-webpage-test-for-frontendsupport]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: WebPageTest Staging
        uses: WPO-Foundation/webpagetest-github-action@main
        with:
          apiKey: ${{ secrets.WPT_API_KEY }}
          urls: |
            https://staging.frontendrescue.com/
            https://staging.frontendrescue.com/posts/2023-07-28-session-storage-playwright
          label: 'GitHub Action Test'
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

One catch is that repository dispatch events will only trigger an event if the workflow is committed to the default branch (usually master/main etc.).

I initially wondered why the event was not triggered when committing to a feature branch, but once the action was in the main branch, the event got triggered.

Repository dispatch events are an excellent way to generalise logic without resorting to the dreaded horrors of copying and pasting.