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GitHub Actions for C++ Projects: CI/CD Pipeline

DevOpsC++

Automate your C++ builds, tests, and releases with GitHub Actions. The key is to make the workflow reproducible, fast, and consistent across platforms.

Core Ideas

1. Use out-of-source builds: Keep artifacts in build/.
2. Test every PR: Fail fast before merge.
3. Cache dependencies: Reduce cold-start time.
4. Publish artifacts: Make binaries easy to download.

Basic Workflow

# .github/workflows/build.yml
name: Build and Test

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

jobs:
  build:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Install dependencies
      run: |
        sudo apt-get update
        sudo apt-get install -y cmake g++ libboost-all-dev
    
    - name: Configure
      run: cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
    
    - name: Build
      run: cmake --build build
    
    - name: Test
      run: cd build && ctest --output-on-failure

Use CMake Presets

If you have CMakePresets.json, your workflow becomes cleaner and consistent with local builds:

- name: Configure
  run: cmake --preset linux-release

- name: Build
  run: cmake --build --preset linux-release

Multi-Platform Build

jobs:
  build:
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
        compiler: [gcc, clang, msvc]
        exclude:
          - os: windows-latest
            compiler: gcc
          - os: ubuntu-latest
            compiler: msvc
    
    runs-on: ${{ matrix.os }}
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Build
      run: |
        cmake -S . -B build -DCMAKE_CXX_COMPILER=${{ matrix.compiler }}
        cmake --build build

Use exclude to avoid invalid compiler/OS combos. For MSVC on Windows, consider using the Visual Studio generator and omit CMAKE_CXX_COMPILER.

Caching Dependencies

- name: Cache dependencies
  uses: actions/cache@v3
  with:
    path: |
      ~/.conan
      build/_deps
    key: ${{ runner.os }}-deps-${{ hashFiles('**/CMakeLists.txt') }}

For faster compiles, add ccache:

- name: Cache ccache
  uses: actions/cache@v3
  with:
    path: ~/.ccache
    key: ${{ runner.os }}-ccache-${{ hashFiles('**/*.cpp', '**/*.h') }}

Code Coverage

- name: Coverage
  run: |
    cmake -B build -DCMAKE_BUILD_TYPE=Debug -DENABLE_COVERAGE=ON
    cmake --build build
    cd build && ctest
    lcov --capture --directory . --output-file coverage.info
    
- name: Upload to Codecov
  uses: codecov/codecov-action@v3
  with:
    files: build/coverage.info

Upload Build Artifacts

- name: Upload artifacts
  uses: actions/upload-artifact@v4
  with:
    name: binaries-${{ matrix.os }}
    path: build/bin/

Release Automation

on:
  push:
    tags:
      - 'v*'

jobs:
  release:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    
    - name: Build Release
      run: |
        cmake -B build -DCMAKE_BUILD_TYPE=Release
        cmake --build build
        cpack --config build/CPackConfig.cmake
    
    - name: Create Release
      uses: softprops/action-gh-release@v1
      with:
        files: build/*.tar.gz

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How do you automate your C++ builds? Share your workflows!

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