Post coverage comment workflow (pydantic/pydantic)

The Post coverage comment workflow from pydantic/pydantic, explained and optimized by Latchkey.

CI health: A - excellent

Point runs-on at Latchkey and get job timeouts, self-healing for flaky steps, and up to 58% lower cost, applied automatically.

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Source: pydantic/pydantic.github/workflows/coverage.ymlLicense MITView source

What it does

This is the Post coverage comment workflow from the pydantic/pydantic 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

workflow (.yml)

name: Post coverage comment

on: # zizmor: ignore[dangerous-triggers] -- workflow_run is used safely here; no code checkout occurs
  workflow_run:
    workflows: ['CI']
    types:
      - completed

jobs:
  post-coverage-comment:
    name: Push coverage comment
    runs-on: ubuntu-latest
    if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
    permissions:
      pull-requests: write
      contents: write
      actions: read
    steps:
      # DO NOT run actions/checkout here, for security reasons
      # For details, refer to https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
      - name: Post comment
        uses: py-cov-action/python-coverage-comment-action@5d8df5979747514c914e1c5a12335a7cf9a2745f # v4.1
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GITHUB_PR_RUN_ID: ${{ github.event.workflow_run.id }}

The same workflow, on Latchkey

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

name: Post coverage comment
 
on: # zizmor: ignore[dangerous-triggers] -- workflow_run is used safely here; no code checkout occurs
  workflow_run:
    workflows: ['CI']
    types:
      - completed
 
jobs:
  post-coverage-comment:
    timeout-minutes: 30
    name: Push coverage comment
    runs-on: latchkey-small
    if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
    permissions:
      pull-requests: write
      contents: write
      actions: read
    steps:
      # DO NOT run actions/checkout here, for security reasons
      # For details, refer to https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
      - name: Post comment
        uses: py-cov-action/python-coverage-comment-action@5d8df5979747514c914e1c5a12335a7cf9a2745f # v4.1
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GITHUB_PR_RUN_ID: ${{ github.event.workflow_run.id }}

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.
Add a job timeout so a hung step cannot burn hours of runner time.

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