Connecting Github Actions across Repositories

I had a request that an iOS swift run command gets triggered every time a deploy was made to a staging server.  This looked like a perfect application for Github Actions.  This strategy can be adapted to any CI system.

So here's how I did it.

The iOS Project

I needed to run the command swift run in a specific directory.  Github Actions uses triggers.  I decided to use a manual trigger called workflow_dispatch.  Later this will let me trigger it using the API.  It also lets me trigger it in the Github UI.

Make a file called .github/workflows/update.yml (the filename can be whatever you like):

name: Update Graphql
on:
  workflow_dispatch

jobs:
  build:
    name: 'Update Graphql Bits'
    runs-on: macOS-latest
	  steps:
	    - name: Checkout
	      users: actions/checkout@master
	    - name: 'Swift Run'
	      run: |
	        cd Codegen
	        swift run

Some notes:

• The name on the first line matters.
• The tabs/spaces indentation is finicky.  Editing this on Github directly is not the worst idea in the world.  Their editor gives you feedback.  Feedback gives you wings.

We also need to commit if there are any changed files.  I used the following:

  - name: Add & Commit
    uses: EndBug/add-and-commit@v7.0.0
    with:
      add: 'External/GraphQL'
      message: '[auto] Updated GraphQL'

There's a caveat about testing workflow_dispatch.  It only works if it's in your main branch.  So I copied our iOS project to a fake one, so I could merge to main and experiment without some git historian coming in one day and wondering why I the least iOS capable engineer has made the most commits to the iOS project.

I ran this a few times in my fake repository to make sure it didn't just keep committing stuff and it worked.  Unfortunately, it probably will commit as me until I create my robot account.

Since we proved the concept in our fake repository, we can now move it to the real repository and commit it to the main branch.

Trigger

The ideal workflow is triggering this command every time we deploy to our staging environment.

name: Staging Deploy

on: deployment_status
jobs:
  trigger:
    name: Trigger
    if: ${{ github.event.deployment.environment == 'staging' && github.event.deployment_status.state == 'success' }}
    steps:
      - name: Invoke workflow in another repo with inputs
        uses: benc-uk/workflow-dispatch@v1
        with:
          workflow: Update Graphql
          repo: alternate/repo
          token: ${{ secrets.PERSONAL_TOKEN }}

This action is pretty slick.  It takes your token (or your robot's token) and triggers the workflow_dispatch as an API call.

To test I added this to another fake project.  This is my role in life, I create fake projects, fake users, etc, etc.  I then used Postman to generate deployments and update the deployment status with the Github API (and using the same PERSONAL_TOKEN that I use in my action.

This totally worked and was easy.  I did run into some debugging issues.

My task kept getting skipped.

I found the Dump Context Action was super valuable for figuring out details of contexts.  My issue (which I fixed in the code above) was an error in the if statement.  A million edits later and it finally worked.

In an ideal world I would check 2 extra things:

• That the sha that was deployed matched up with the head of main.
• That the files affected were related to GraphQL.

But I'm okay with this compromise.  My experience is with Jenkins for this type of workload management.  I've used Circle CI for smaller operations, but Github Actions was very nice.  The marketplace of actions and having this part of Github made this a breeze.  Github is already the nexus for so much of our software life-cycle.

Onto the next challenge.

References

Need help?  Ask - I know I left out details, I write this in my spare time and honestly I'm super tired:  githubactions@davedash.33mail.com

Want to build Rube-Goldberg machines with me, or make slow things fast, work with me: workwithme@davedash.33mail.com  I work at small startup of empathetic engineers and designers.