# Github Actions

> When to activate: GitHub Actions, workflow, .github/workflows, jobs, steps, matrix, secrets, environments, reusable workflow, act

- Skill: `mattakushi432/github-actions` (Agent Skill)
- Install (CLI): `npx skillmds@latest add mattakushi432/github-actions`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mattakushi432/github-actions/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: Mattakushi432 (https://skillmd.com/u/mattakushi432)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/mattakushi432/github-actions

---

# GitHub Actions Patterns

## Complete CI Workflow

```yaml
name: CI

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

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

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm

      - run: npm ci
      - run: npm run lint
      - run: npm test -- --coverage

      - uses: codecov/codecov-action@v4
        with:
          token: ${{ secrets.CODECOV_TOKEN }}
```

## Matrix Build

```yaml
jobs:
  test:
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest]
        node: [18, 20, 22]
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node }}
      - run: npm ci && npm test
```

## Docker Build & Push

```yaml
jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
    steps:
      - uses: actions/checkout@v4

      - uses: docker/setup-buildx-action@v3

      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - uses: docker/metadata-action@v5
        id: meta
        with:
          images: ghcr.io/${{ github.repository }}
          tags: |
            type=sha,prefix=
            type=ref,event=branch
            type=semver,pattern={{version}}

      - uses: docker/build-push-action@v5
        with:
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          cache-from: type=gha
          cache-to: type=gha,mode=max
```

## Deploy to Kubernetes with Environment Gates

```yaml
jobs:
  deploy-staging:
    needs: build
    runs-on: ubuntu-latest
    environment: staging
    steps:
      - uses: actions/checkout@v4
      - uses: azure/k8s-set-context@v4
        with:
          kubeconfig: ${{ secrets.KUBECONFIG_STAGING }}
      - run: |
          kubectl set image deployment/myapp \
            myapp=ghcr.io/${{ github.repository }}:${{ github.sha }}
          kubectl rollout status deployment/myapp

  deploy-prod:
    needs: deploy-staging
    runs-on: ubuntu-latest
    environment: production  # requires manual approval
    steps:
      - uses: azure/k8s-set-context@v4
        with:
          kubeconfig: ${{ secrets.KUBECONFIG_PROD }}
      - run: |
          kubectl set image deployment/myapp \
            myapp=ghcr.io/${{ github.repository }}:${{ github.sha }}
```

## Reusable Workflow

```yaml
# .github/workflows/reusable-test.yml
on:
  workflow_call:
    inputs:
      node-version:
        required: true
        type: string
    secrets:
      NPM_TOKEN:
        required: true

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
        env:
          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
      - run: npm test
```

```yaml
# Caller workflow
jobs:
  test:
    uses: ./.github/workflows/reusable-test.yml
    with:
      node-version: "20"
    secrets:
      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
```

## Scheduled Job + Slack Notification

```yaml
on:
  schedule:
    - cron: '0 8 * * 1-5'  # Weekdays 8am UTC

jobs:
  report:
    runs-on: ubuntu-latest
    steps:
      - run: ./scripts/generate-report.sh
      - if: failure()
        uses: slackapi/slack-github-action@v1
        with:
          payload: '{"text":"Report generation failed: ${{ github.run_url }}"}'
        env:
          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK }}
```

## Key Rules
- Pin action versions to full SHA for security: `uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683`
- Use `concurrency` to cancel stale PR runs
- Never put secrets in `run:` commands — use `env:` block
- `GITHUB_TOKEN` permissions: set minimum required (`contents: read`)
- Use `workflow_dispatch` for manual triggers with inputs