Optimizing GitHub Actions: Conditional Job Triggers and Workflow Organization

[AlaricThorn]

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I’m working on setting up a GitHub Actions workflow for our project, but I’m a bit stuck. I understand the basics of using jobs and steps, but I’m trying to figure out how to optimize the workflow’s efficiency. Specifically, I want to avoid rerunning jobs when nothing has changed in a certain directory. Do you have any insights on how to handle that?

[c0decr4ft3r]

Good question, my man, @AlaricThorn.

Optimizing workflows is important for saving time and resources. In GitHub Actions, you can conditionally trigger jobs based on path changes, which seems to be exactly what you’re looking for. You’ll want to make use of the paths filter within the workflow triggers.

Here’s a quick rundown:

1. Use the paths filter: This allows you to specify which files or directories should trigger the workflow. For example:

on:  
  push:    
    paths:      
      - 'src/**'

This will only trigger the workflow when files within the src directory change. But that’s at the workflow level.

2. Control jobs within the workflow: If you want finer control, say, having one job execute only when specific files change, you’ll need to use if conditions with github.event data. You could set up environment variables or use custom expressions to check file changes at the job or step level.

Here’s a common pattern:

jobs:  
  example-job:  
    runs-on: ubuntu-latest  
    steps:  
      - name: Check out code  
        uses: actions/checkout@v2  
      - name: Run job only if certain files changed  
        if: ${{ contains(github.event.head_commit.message, 'specific-directory') }}  
        run: echo "Changes detected in specific-directory"

This approach gives you flexibility at both the workflow and job level. If you find that you’re constantly filtering jobs, you might want to consider splitting up your workflows entirely to handle specific directories independently.

Another advanced option is using GitHub’s paths-ignore filter to skip certain files or directories. This can help if you need the workflow to run more often but exclude irrelevant changes (like documentation updates).

See if this helps you. Just ping me for more examples on setting up conditional triggers.
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[AlaricThorn]

I kinda understood it and it gave me a better perspective, thanks!

I have one more question though: what if I have two directories that I want to monitor separately within the same workflow? Say, one for backend changes and one for frontend. Would it be better to handle these in the same workflow with conditional steps, or split them into two separate workflows?

[c0decr4ft3r]

It depends on the dependencies between those two parts.

If the backend and frontend changes are often related and you need a coordinated deployment or test setup, keeping them within the same workflow makes sense. You can separate the jobs with conditions like I mentioned earlier, using paths and if conditions to differentiate between them:

on:
  push:
    paths:
      - 'backend/**'
      - 'frontend/**'

jobs:
  backend-job:
    runs-on: ubuntu-latest
    if: ${{ github.event_name == 'push' && github.event.commits.some(commit => commit.modified.some(file => file.startsWith('backend/'))) }}
    steps:
      # backend specific steps

  frontend-job:
    runs-on: ubuntu-latest
    if: ${{ github.event_name == 'push' && github.event.commits.some(commit => commit.modified.some(file => file.startsWith('frontend/'))) }}
    steps:
      # frontend specific steps

But if the two are fairly independent, separating them into distinct workflows has advantages:

1. It keeps your CI/CD pipeline modular and easier to maintain.
2. You’ll get clearer logs and statuses, specific to backend or frontend workflows.
   For more complex projects, I generally lean towards multiple workflows. It’s a bit of an initial overhead, but it pays off in clarity and flexibility.

All clear?
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[AlaricThorn]

Thank you!
All clear!

[chamakov]

Is this approach still valid? Trying but seeing this Unexpected symbol: '('. Located at position 57 within expression: github.event_name == 'push' && github.event.commits.some(commit => commit.modified.some(file => file.startsWith('backend/')))

[AlaricThorn]

This helped me a lot!

[c0decr4ft3r]

Nice!
I added you to a repo inside my organisation. You can see details about conditional job triggering there!
Glad I could help!
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[AlaricThorn]

Thank you, man!