🎟️
turnstyle

A GitHub Action for serializing workflow runs

🤔 why bother

GitHub Actions is an event-oriented system. Your workflows run in response to events and are triggered independently and without coordination. In a shared repository, if two or more people merge pull requests, each will trigger workflows without regard to one another.

This can be problematic for workflows used as part of a continuous deployment process. You might want to let an in-flight deployment complete before progressing further with the next workflow. This is the usecase turnstyle action targets.

🤸 Usage

The typical setup for turnstyle involves adding job step using softprops/turnstyle@v1.

name: Main

on: push

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
+     - name: Turnstyle
+       uses: softprops/turnstyle@v1
+       env:
+         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy
        run: sleep 30

Timing out

To avoid waiting prolonged periods of time, you may wish to bail on a run or continuing a workflow run regardless of the status of the previous run.

You can bail from a run using the built-in GitHub Actions jobs.<job_id>.timeout-minutes setting

name: Main

on: push

jobs:
  main:
+   timeout-minutes: 5
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Turnstyle
        uses: softprops/turnstyle@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy
        run: sleep 30

You can also limit how long you're willing to wait before moving on with jobs.<job_id>.steps.with.continue-after-seconds

name: Main

on: push

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Turnstyle
        uses: softprops/turnstyle@v1
        with:
+         continue-after-seconds: 180
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy
        run: sleep 30

or before aborting the step with jobs.<job_id>.steps.with.abort-after-seconds

name: Main

on: push

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Turnstyle
        uses: softprops/turnstyle@v1
        with:
+         abort-after-seconds: 180
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy
        run: sleep 30

Finally, you can use the force_continued output to skip only a subset of steps by setting continue-after-seconds and conditioning future steps with if: ! steps.<step id>.outputs.force_continued

name: Main

on: push

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Turnstyle
        id: turnstyle
        uses: softprops/turnstyle@v1
        with:
+         continue-after-seconds: 180
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy
+       if: ! steps.turnstyle.outputs.force_continued
        run: sleep 30

inputs

Name	Type	Description
`continue-after-seconds`	number	Maximum number of seconds to wait before moving forward (unbound by default). Mutually exclusive with abort-after-seconds
`abort-after-seconds`	number	Maximum number of seconds to wait before aborting the job (unbound by default). Mutually exclusive with continue-after-seconds
`poll-interval-seconds`	number	Number of seconds to wait in between checks for previous run completion (defaults to 60)
`same-branch-only`	boolean	Only wait on other runs from the same branch (defaults to true)
`initial-wait-seconds`	number	Total elapsed seconds within which period the action will refresh the list of current runs, if no runs were found in the first attempt

outputs

Name	Type	Description
`force_continued`	boolean	True if continue-after-seconds is used and the step using turnstyle continued. False otherwise.

environment variables

The following are required as step.env keys

Name	Description
`GITHUB_TOKEN`	GITHUB_TOKEN as provided by `secrets`

required permissions

Because this application leverages the GITHUB_TOKEN to make API requests, the permissions granted to the token must be sufficient to make the API requests. By default, the token has wide enough permissions to allow all API requests made by this action. If you are customizing your token permissions, you must explicitly specify all permissions, including those that you need that would otherwise be granted by the defaults. See "Permissions for the GITHUB_TOKEN" In the GitHub Actions documentation.

If you need to specify explicit permissions for the API requests made by this action, the permissions required are:

actions:read - this permission is required for the listWorkflowRunsForRepo API request.

cost of coordination

At this time there is no way to coordinate between workflow runs beyond waiting. For those using private repositories, you are charged based on the time your workflow spends running. Waiting within one workflow run for another to complete will incur the cost of the time spent waiting.

Doug Tangren (softprops) 2020

zachwhaley/turnstyle

🎟️ turnstyle