Dependabot automerge workflow (samber/mo)

The Dependabot automerge workflow from samber/mo, explained and optimized by Latchkey.

What it does

This is the Dependabot automerge workflow from the samber/mo repository, a real project running GitHub Actions. It is shown here with attribution under its MIT license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

name: Dependabot automerge

on:
  pull_request:
    types: [opened, synchronize]

jobs:
  automerge:
    runs-on: ubuntu-latest
    if: github.actor == 'dependabot[bot]'
    permissions:
      contents: write
      pull-requests: write
    steps:
      - name: Fetch Dependabot metadata
        id: metadata
        uses: dependabot/fetch-metadata@v3

      - name: Enable auto-merge for github-actions updates
        if: steps.metadata.outputs.package-ecosystem == 'github_actions'
        run: gh pr merge --auto --squash "$PR_URL"
        env:
          PR_URL: ${{ github.event.pull_request.html_url }}
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

The same workflow, on Latchkey

Removes redundant runs and caps runaway jobs. Added and changed lines are highlighted.

name: Dependabot automerge
 
on:
  pull_request:
    types: [opened, synchronize]
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  automerge:
    timeout-minutes: 30
    runs-on: latchkey-small
    if: github.actor == 'dependabot[bot]'
    permissions:
      contents: write
      pull-requests: write
    steps:
      - name: Fetch Dependabot metadata
        id: metadata
        uses: dependabot/fetch-metadata@v3
 
      - name: Enable auto-merge for github-actions updates
        if: steps.metadata.outputs.package-ecosystem == 'github_actions'
        run: gh pr merge --auto --squash "$PR_URL"
        env:
          PR_URL: ${{ github.event.pull_request.html_url }}
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
 

What changed

• Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
• Cancel superseded runs when a branch or PR gets a newer push.
• Add a job timeout so a hung step cannot burn hours of runner time.

1 third-party action is referenced by a movable tag. Pin it to the commit SHA (Latchkey resolves and applies this automatically) so a repointed tag cannot change what runs.

This workflow runs 1 job per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.