How to Reduce CI Cost by Consolidating Jobs

Each job provisions a fresh runner, checks out the repo, and restores caches, so ten one-minute jobs cost far more than one ten-minute job.

Where jobs do not need real parallelism or different runners, fold them into one job with sequential steps to pay the setup tax once.

Steps

• List jobs that each do a few seconds of work on the same runner.
• Merge lint, typecheck, and unit tests into one job when they share setup.
• Keep genuinely long or independent work as separate parallel jobs.

Workflow

jobs:
  checks:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm run lint
      - run: npm run typecheck
      - run: npm test

Gotchas

• Merging serializes steps, so it trades a little wall-clock time for lower cost.
• Do not merge jobs that need different runner sizes or operating systems.
• Billing rounds each job up to the nearest minute, so many short jobs round up repeatedly.

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