github-actions-ci

name	github-actions-ci
description	Develop and troubleshoot GitHub Actions workflows and CI configurations. Use when creating workflows, debugging CI failures, understanding job logs, or optimizing CI pipelines.

GitHub Actions CI Development

Guide for developing, debugging, and optimizing GitHub Actions workflows and CI configurations.

When to Use This Skill

• Creating new GitHub Actions workflows
• Debugging CI failures from job logs
• Understanding workflow syntax and features
• Optimizing CI performance
• Troubleshooting permission or environment issues

Workflow Structure

File Location

Workflows live in .github/workflows/ with .yml or .yaml extension.

Basic Structure

name: Workflow Name

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  job-name:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Step name
        run: echo "Hello"

Debugging CI Failures

Step 1: Get the Job Log URL

When a PR check fails, the user typically provides a URL like: https://github.com/owner/repo/actions/runs/12345/job/67890

Step 2: Fetch and Analyze Logs

Use GitHub CLI to get detailed logs:

gh run view <run-id> --log-failed

Or fetch specific job logs:

gh api repos/owner/repo/actions/jobs/<job-id>/logs

Step 3: Identify the Failure Point

Look for:

• Exit codes (non-zero indicates failure)
• Error messages in red/highlighted text
• The specific step that failed
• Environment or dependency issues

Step 4: Reproduce Locally

Always try to reproduce the failure locally before pushing fixes:

# For Homebrew taps
brew test-bot --only-tap-syntax

# For Node projects
npm ci && npm test

# For general linting
<linter> --config <config-file> <files>

Common CI Patterns

Matrix Builds

Test across multiple OS/versions:

jobs:
  test:
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest]
        node: [18, 20]
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node }}

Conditional Steps

- name: Only on main
  if: github.ref == 'refs/heads/main'
  run: echo "On main branch"

- name: Only on PR
  if: github.event_name == 'pull_request'
  run: echo "This is a PR"

Caching Dependencies

- uses: actions/cache@v4
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
    restore-keys: |
      ${{ runner.os }}-node-

Artifacts

Upload build outputs:

- uses: actions/upload-artifact@v4
  with:
    name: build-output
    path: dist/

Homebrew-Specific CI

Homebrew Test Bot

The standard CI for Homebrew taps uses Homebrew/actions/build-bottle:

name: Test Formula

on:
  pull_request:
    paths:
      - 'Formula/**'

jobs:
  test-bot:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-22.04, macos-latest]
    steps:
      - uses: actions/checkout@v4
      - uses: Homebrew/actions/setup-homebrew@master
      - run: brew test-bot --only-tap-syntax
      - run: brew test-bot --only-formulae

Common Homebrew CI Failures

Failure	Cause	Solution
brew style errors	Rubocop violations	Run brew test-bot --only-tap-syntax locally
Ruby in markdown	rubocop-md lints ruby code fences	Use text fence language instead
Formula audit errors	Missing fields or bad values	Run brew audit --new --formula <name>
Test failures	Test block issues	Verify test block creates needed files

Troubleshooting Techniques

Check Workflow Syntax

# Validate YAML syntax
yamllint .github/workflows/

# Check with actionlint (if installed)
actionlint .github/workflows/

View Recent Runs

gh run list --limit 10
gh run view <run-id>
gh run view <run-id> --log

Re-run Failed Jobs

gh run rerun <run-id> --failed

Check PR Status

gh pr view <pr-number> --json statusCheckRollup

Watch CI Progress

gh run watch <run-id>

Environment and Secrets

Using Secrets

env:
  API_KEY: ${{ secrets.API_KEY }}

GitHub Token

The GITHUB_TOKEN is automatically available:

env:
  GH_TOKEN: ${{ github.token }}

Environment Variables

env:
  NODE_ENV: production

jobs:
  build:
    env:
      CI: true
    steps:
      - env:
          STEP_VAR: value
        run: echo $STEP_VAR

Performance Optimization

Parallel Jobs

Jobs run in parallel by default. Use needs for dependencies:

jobs:
  lint:
    runs-on: ubuntu-latest
    steps: [...]

  test:
    runs-on: ubuntu-latest
    steps: [...]

  deploy:
    needs: [lint, test]  # Waits for both
    runs-on: ubuntu-latest
    steps: [...]

Path Filtering

Only run on relevant changes:

on:
  push:
    paths:
      - 'src/**'
      - 'package.json'
    paths-ignore:
      - '**.md'
      - 'docs/**'

Concurrency Control

Cancel redundant runs:

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

Debugging Checklist

• Read the full error message in job logs
• Identify which step failed
• Check if it's a flaky test or consistent failure
• Reproduce locally with same commands
• Verify all dependencies and versions match
• Check for environment-specific issues (OS, permissions)
• Review recent changes that might have caused the failure
• Push fix and verify CI passes

Local Testing with act

nektos/act runs GitHub Actions locally using Docker, enabling fast iteration without pushing to GitHub.

Installation

# macOS
brew install act

# Other platforms
curl -s https://raw.githubusercontent.com/nektos/act/master/install.sh | sudo bash

Basic Usage

# Run all workflows triggered by push
act push

# Run all workflows triggered by pull_request
act pull_request

# Run a specific job
act -j build

# Run with a specific event payload
act pull_request -e event.json

# List available jobs without running
act -l

# Run with verbose output
act -v

Secrets and Variables

# Pass secrets via file
act --secret-file .secrets

# Pass individual secrets
act -s GITHUB_TOKEN="$(gh auth token)"

# Pass environment variables
act --env-file .env

Runner Images

# Use medium image (default, smaller but missing some tools)
act -P ubuntu-latest=catthehacker/ubuntu:act-latest

# Use large image (closer to GitHub runners, ~12GB)
act -P ubuntu-latest=catthehacker/ubuntu:full-latest

# Use micro image (fastest, minimal tools)
act -P ubuntu-latest=node:16-buster-slim

Limitations

Limitation	Workaround
Some actions don't work	Use -P to specify compatible runner images
No macOS/Windows runners	Test OS-specific code on actual GitHub runners
Service containers differ	May need Docker Compose for complex setups
GitHub context differences	Some github.* values unavailable locally
Large image downloads	Use micro images for simple workflows

When to Use act

• Use act: Rapid iteration, testing matrix logic, validating workflow syntax, testing secret handling
• Skip act: OS-specific tests, actions requiring GitHub API, final validation before merge

Pre-commit Hooks for Workflows

Catch workflow errors before commit to reduce failed CI runs.

actionlint Hook

The most important hook - catches syntax errors, type mismatches, and common mistakes.

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/rhysd/actionlint
    rev: v1.7.4
    hooks:
      - id: actionlint
        files: ^\.github/workflows/

yamllint Hook

Validates YAML structure and formatting.

repos:
  - repo: https://github.com/adrienverge/yamllint
    rev: v1.35.1
    hooks:
      - id: yamllint
        files: ^\.github/workflows/
        args: [--config-file, .yamllint.yml]

Recommended .yamllint.yml for GitHub Actions:

extends: default
rules:
  line-length:
    max: 120
  truthy:
    check-keys: false  # Allows 'on:' without quotes
  comments:
    min-spaces-from-content: 1

check-yaml Hook

Basic YAML validity check.

repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.6.0
    hooks:
      - id: check-yaml
        files: ^\.github/workflows/
        args: [--unsafe]  # Required for GitHub Actions syntax

Complete Pre-commit Config

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.6.0
    hooks:
      - id: check-yaml
        files: ^\.github/workflows/
        args: [--unsafe]

  - repo: https://github.com/adrienverge/yamllint
    rev: v1.35.1
    hooks:
      - id: yamllint
        files: ^\.github/workflows/
        args: [-c, .yamllint.yml]

  - repo: https://github.com/rhysd/actionlint
    rev: v1.7.4
    hooks:
      - id: actionlint

Manual Validation

# Run actionlint on all workflows
actionlint

# Run on specific file
actionlint .github/workflows/ci.yml

# With shellcheck integration (recommended)
actionlint -shellcheck=$(which shellcheck)

Claude Hooks for Workflow Development

Configure Claude Code hooks to automatically validate workflows during development.

Post-Edit Hook: actionlint

Run actionlint after editing workflow files.

// .claude/settings.json
{
  "hooks": {
    "post_edit": [
      {
        "pattern": "^\\.github/workflows/.*\\.ya?ml$",
        "command": "actionlint",
        "description": "Lint GitHub Actions workflow"
      }
    ]
  }
}

Pre-Commit Hook: Full Validation

Validate before committing workflow changes.

{
  "hooks": {
    "pre_commit": [
      {
        "pattern": "^\\.github/workflows/.*\\.ya?ml$",
        "command": "actionlint && yamllint .github/workflows/",
        "description": "Validate GitHub Actions workflows"
      }
    ]
  }
}

Suggested Claude Workflow

1. Edit workflow file
2. Hook runs actionlint automatically
3. Fix any reported issues
4. Commit triggers pre-commit hooks
5. Push with confidence - first CI run more likely to pass

Reusable Actions and Workflows

Action Source Priority

Always prefer actions from arustydev/gha for consistency and control.

Priority order:

1. arustydev/gha - First choice for all actions
2. Third-party action - Temporary fallback with issue tracking
3. Local development - When no suitable action exists

Using arustydev/gha Actions

steps:
  - uses: arustydev/gha/setup-node@v1
  - uses: arustydev/gha/deploy-preview@v1

When Action Not in arustydev/gha

If a needed action exists from a third party but not in arustydev/gha:

1. Create tracking issue:

   gh issue create --repo arustydev/gha \
     --title "[ACTION] Add <action-name>" \
     --body "Third-party equivalent: <owner>/<action>@<version>
   
   Currently using third-party version in: <project-name>
   
   Requested functionality: <description>"
   

2. Use third-party temporarily:

   steps:
     # TODO: Replace with arustydev/gha/<action> when available
     # Tracking: https://github.com/arustydev/gha/issues/XX
     - uses: third-party/action@v1
   

When No Suitable Action Exists

If no action (arustydev/gha or third-party) meets the need:

1. Create needs issue:

   gh issue create --repo arustydev/gha \
     --title "[ACTION] Need <action-name>" \
     --body "## Use Case
   <describe the need>
   
   ## Proposed Solution
   <high-level approach>
   
   ## Initial Development
   Will develop locally in: <project-name>"
   

2. Develop locally in the project:

   .github/
   └── actions/
       └── my-action/
           ├── action.yml
           ├── package.json
           ├── tsconfig.json
           └── src/
               └── index.ts
   

3. Use TypeScript/Node for development:

   # .github/actions/my-action/action.yml
   name: My Action
   description: Does something useful
   inputs:
     example:
       description: Example input
       required: true
   runs:
     using: node20
     main: dist/index.js
   

   // .github/actions/my-action/src/index.ts
   import * as core from '@actions/core';
   import * as github from '@actions/github';
   
   async function run(): Promise<void> {
     try {
       const example = core.getInput(, { :  });
       core.();
       
     }  (error) {
        (error  ) {
         core.(error.);
       }
     }
   }
   
   ();
   

Reusable Workflows

For complex multi-job workflows, use reusable workflows:

# In arustydev/gha/.github/workflows/node-ci.yml
name: Node CI
on:
  workflow_call:
    inputs:
      node-version:
        type: string
        default: '20'

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ inputs.node-version }}
      - run: npm ci && npm test

# In your project
jobs:
  ci:
    uses: arustydev/gha/.github/workflows/node-ci.yml@main
    with:
      node-version: '20'

References

• GitHub Actions Documentation
• Workflow Syntax Reference
• GitHub CLI Manual
• Homebrew/actions
• actionlint - GitHub Actions linter
• nektos/act - Run GitHub Actions locally
• arustydev/gha - Centralized reusable actions
• @actions/core - Action toolkit for TypeScript
• Creating JavaScript Actions