Workflow Chaining in GitHub Actions

Workflow chaining in GitHub Actions allows you to create complex CI/CD processes by linking multiple workflows together. This enables you to trigger follow-up workflows based on the success or failure of previous ones, enhancing modularity and maintainability in your automation processes.

• **Workflow**: A configurable automated process made up of one or more jobs.
• **Job**: A set of steps executed on the same runner.
• **Event**: A trigger that starts a workflow, such as a push or pull request.
• **Artifact**: Files generated by a workflow that can be reused in other workflows.

Workflow chaining involves using the workflow_run event to create dependencies between workflows. This allows one workflow to react to the completion of another. You can specify conditions on when to trigger the chained workflows based on the status (success, failure, etc.) of the preceding workflow.

yaml
name: Main Workflow
on: push

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      - name: Build
        run: echo "Building!"

---

name: Chained Workflow
on:
  workflow_run:
    workflows: ["Main Workflow"]
    types:
      - completed

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Deploy
        run: echo "Deploying!"

1. Define your main workflow as usual with the triggering event.
2. Create a second workflow that uses workflow_run to listen for the main workflow's completion.
3. Set conditions in the second workflow based on the result of the first workflow.
4. Test your workflows to ensure they trigger correctly based on the conditions set.

mermaid
graph TD;
    A[Main Workflow] -->|Success| B[Chained Workflow]
    A -->|Failure| C[Notify Failure]

Following best practices can enhance the effectiveness of workflow chaining:

• Use descriptive names for your workflows and jobs for better clarity.
• Incorporate error handling to manage failures gracefully.
• Keep workflows modular to improve reusability and maintainability.
• Document the workflows clearly to help onboard new contributors.