Job Dependencies

The DAG

Jobs in a workflow form a directed acyclic graph (DAG) based on their needs: fields. Athanor uses Kahn’s algorithm to topologically sort jobs into levels. Jobs at the same level run concurrently.

Simple Chain

jobs:
  first:
    steps:
      - run: echo "first"
  second:
    needs: first
    steps:
      - run: echo "second"
  third:
    needs: second
    steps:
      - run: echo "third"

Execution: first → second → third (sequential).

Fan-Out / Fan-In

jobs:
  lint:
    steps:
      - run: echo "lint"
  test:
    needs: lint
    steps:
      - run: echo "test"
  build:
    needs: lint
    steps:
      - run: echo "build"
  deploy:
    needs: [test, build]
    steps:
      - run: echo "deploy"

Execution:

lint ──┬── test  ──┬── deploy
       └── build ──┘

test and build run in parallel after lint completes. deploy waits for both.

Failure Propagation

If a job fails, all jobs that depend on it (directly or transitively) are skipped:

lint (fails) ──┬── test  (skipped)
               └── build (skipped) ── deploy (skipped)

The workflow finishes with a failure status.

Cycle Detection

Circular dependencies are caught at parse time:

jobs:
  a:
    needs: b
    steps:
      - run: echo "a"
  b:
    needs: a
    steps:
      - run: echo "b"

This produces an error: cycle detected in job dependencies.

No Dependencies

Jobs with no needs: field all run in the first level, concurrently:

jobs:
  lint:
    steps:
      - run: echo "lint"
  test:
    steps:
      - run: echo "test"
  build:
    steps:
      - run: echo "build"

All three start at the same time.

Getting Started

Guides

Reference

Job Dependencies

The DAG

Simple Chain

Fan-Out / Fan-In

Failure Propagation

Cycle Detection

No Dependencies

​The DAG

​Simple Chain

​Fan-Out / Fan-In

​Failure Propagation

​Cycle Detection

​No Dependencies

The DAG

Simple Chain

Fan-Out / Fan-In

Failure Propagation

Cycle Detection

No Dependencies