Pipeline triggers and chains — workflow_run and workflow_call

Intra-workflow needs: declares edges between jobs in the same workflow file. Inter-workflow chains declare edges between workflows. Two mechanisms matter: on.workflow_run and on.workflow_call. One graph, two mechanisms.

workflow_run: chain after another workflow

on.workflow_run fires when another workflow completes.

on:
  workflow_run:
    workflows: ["ci"]
    types: [completed]
    branches: [main]

Fires after ci completes on main. Receives github.event.workflow_run; default waits for the upstream’s final job.

workflow_call: call as a reusable step

on.workflow_call makes a workflow callable via uses:.

on:
  workflow_call:
    inputs:
      environment:
        required: true
        type: string
    secrets:
      deploy_key:
        required: true

jobs:
  deploy:
    runs-on: ubuntu-latest
    environment: ${ inputs.environment }
    steps:
      - run: deploy.sh
        env:
          DEPLOY_KEY: ${ secrets.deploy_key }

Caller:

jobs:
  release:
    uses: ./.github/workflows/deploy.yml
    with:
      environment: production
    secrets:
      deploy_key: ${ secrets.DEPLOY_KEY }

The called workflow runs in the caller’s context.

Inter-workflow versus intra-workflow

flowchart LR
    subgraph W1["ci.yml"]
        B["build"] --> T["test"]
        T --> D["deploy"]
    end
    W1 -->|workflow_run| W2["notify.yml"]

• needs: orders jobs in one file.
• workflow_run orders workflows across files.
• workflow_call makes a workflow a step in another.

Filter chains deliberately

on:
  workflow_run:
    workflows: ["ci"]
    types: [completed]
    branches: [main, release/*]

branches: uses the same glob as on.push.branches. types: selects completed / requested / in_progress; only completed matters.

Production discipline

1. workflow_run cross-file; needs: in-file.
2. Filter workflow_run by branch and outcome.
3. Pass secrets to workflow_call explicitly.
4. Document the cross-file DAG.

Cross-course references

• Ansible for Production Sysadmins - Part XXXVII uses the same composition in AWX.
• Linux for Production Sysadmins - Part XXX uses systemd timers.

Quiz