Advanced GitHub Actions Patterns

Advanced GitHub Actions Patterns

GitHub Actions can do far more than basic CI. Matrix builds, reusable workflows, composite actions, and smart caching can dramatically speed up your pipelines and reduce duplication.

Matrix Builds

Test across multiple versions, operating systems, or configurations in parallel:

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

Dynamic Matrix

Generate the matrix from a previous step:

jobs:
  prepare:
    runs-on: ubuntu-latest
    outputs:
      packages: ${{ steps.find.outputs.packages }}
    steps:
      - uses: actions/checkout@v4
      - id: find
        run: |
          packages=$(ls packages/*/package.json | jq -R -s -c 'split("\n") | map(select(. != "")) | map(split("/")[1])')
          echo "packages=$packages" >> "$GITHUB_OUTPUT"

  test:
    needs: prepare
    strategy:
      matrix:
        package: ${{ fromJson(needs.prepare.outputs.packages) }}
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: cd packages/${{ matrix.package }} && npm test

Reusable Workflows

Define a workflow once and call it from multiple repositories:

.github/workflows/ci-template.yml (in shared repo)
on:
  workflow_call:
    inputs:
      node-version:
        type: string
        default: "20"
    secrets:
      NPM_TOKEN:
        required: true

jobs:
  build:
    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 run build
      - run: npm test

Call it from another repo:

jobs:
  ci:
    uses: my-org/shared-workflows/.github/workflows/ci-template.yml@main
    with:
      node-version: "20"
    secrets:
      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

Composite Actions

Bundle multiple steps into a single reusable action:

.github/actions/setup-project/action.yml
name: Setup Project
description: Install deps and build
inputs:
  node-version:
    default: "20"

runs:
  using: composite
  steps:
    - uses: actions/setup-node@v4
      with:
        node-version: ${{ inputs.node-version }}
        cache: npm
    - run: npm ci
      shell: bash
    - run: npm run build
      shell: bash

Smart Caching

Cache dependencies and build outputs to speed up runs:

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

Secrets Management

Use environment-level secrets for deployment credentials:

jobs:
  deploy:
    environment: production
    runs-on: ubuntu-latest
    steps:
      - run: deploy --token ${{ secrets.DEPLOY_TOKEN }}

Concurrency Control

Prevent duplicate runs and cancel outdated deployments:

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

Conclusion

Use matrix builds for cross-platform testing, reusable workflows to share CI logic across repos, composite actions to bundle common steps, and aggressive caching to cut build times. These patterns transform GitHub Actions from basic CI into a powerful automation platform.