Gitlab CI/CD Example for C++-based Apps

CONTENTS

• DEPENDENCIES
• SETUP
• USAGE
• ISSUES
• DOCUMENTATION

DEPENDENCIES

• The main requirements are:
  • Ubuntu 16.04
  • cmake 3.5.1
    • g++ 5.4.0 (needed by CMake to compile CXX files)
  • googletest 1.8.1
    • git 2.7.4 (for downloading googletest within CMake)
    • libpthread-stubs0-dev 0.3-4 (for linking pthread)
  • lcov 1.12 (for generating code coverage)
  • Access to a Gitlab instance
  • Access to a build/test/server PC for gitlab-runner

SETUP

• Setup the Local Test Environment
  • Using your own Ubuntu system
    • Install gcc, cmake, git, and pthread

      $ sudo apt-get update
      $ sudo apt-get install g++=4:5.3.1-1ubuntu1
      $ sudo apt-get install lcov=1.12-2
      $ sudo apt-get install cmake=3.5.1-1ubuntu3
      $ sudo apt-get install git=1:2.7.4-0ubuntu1.6
      $ sudo apt-get install libpthread-stubs0-dev=0.3-4
      
      

    • Build the application and the tests

      $ cd build
      $ cmake ..
      $ make -j8
      
      

  • Using Docker
    • Create a Docker image from the Dockerfile

      docker build --tag sample-ci-cpp .
      docker run -it sample-ci-cpp:latest /bin/bash
      
      

• Setup Gitlab CI
  • Install a Gitlab Runner on a publicly-accessible machine
  • Register the Runner with your Gitlab instance
    • Get the coordinator URL and registration tokens:
      • For shared runners: http://your/gitlab/instance/admin/runners
      • For project-specific runners: http://your/gitlab/project/settings/ci_cd
    • Use Docker as the executor (see ISSUES section on possible disk space issue)
    • Set project-specific tags
  • Configure the CI configuration in .gitlab-ci.yml
    • Set which Docker image and services to use
    • Set the tags
    • Set the commands for before_script and script
    • For other configurations, see GitLab CI/CD Pipeline Configuration Reference
  • Configure the Gitlab Runner at Gitlab project > Settings > CI/CD
    • Select Disable AutoDevOps to explicitly require .gitlab-ci.yml
    • Enable the runner only for "important" commits
      • Enable only on tagged jobs
      • Enable only on protected branches (ex. develop, master)
    • Set other options such as Timeout, Custom CI config path, and Triggers
    • Sample Configuration:

USAGE

• Run the Tests on Local
  • Run the tests

    $ cd build
    $ ./bin/calculator_tests
    [==========] Running 3 tests from 2 test cases.
    [----------] Global test environment set-up.
    [----------] 1 test from AddTest
    [ RUN      ] AddTest.ValidNumbers
    [       OK ] AddTest.ValidNumbers (0 ms)
    [----------] 1 test from AddTest (0 ms total)
    
    [----------] 2 tests from DivTest
    [ RUN      ] DivTest.ValidNumbers
    [       OK ] DivTest.ValidNumbers (0 ms)
    [ RUN      ] DivTest.InvalidNumbers
    [       OK ] DivTest.InvalidNumbers (0 ms)
    [----------] 2 tests from DivTest (0 ms total)
    
    [----------] Global test environment tear-down
    [==========] 3 tests from 2 test cases ran. (1 ms total)
    [  PASSED  ] 3 tests.
    
    

  • Check code coverage

    $ cd build
    $ cd CMakeFiles/calculator_tests.dir/
    $ lcov --directory . --capture -o coverage.info
    $ lcov -r coverage.info */build/* */tests/* */c++/* -o coverageFiltered.info
    $ lcov --list coverageFiltered.info
    
    

• Run the Tests on Gitlab
  • Make changes in src/ and in tests/
  • Make changes to the .gitlab-ci.yml configuration (if necessary)
  • Commit the changes then push to Gitlab
  • Go to the Gitlab project > CI/CD > Pipelines
  • Select the currently running job to view progress/result
  • It is possible to download the job log by clicking on the Raw button

ISSUES

• The tests and the code coverage does not seem to be using latest src and tests
  • Delete the build directory then re-create it

    $ rm -Rf build
    $ mkdir build
    $ touch .gitkeep
    
    

• "This job is stuck, because you don’t have any active runners that can run this job."
  • Make sure that the .gitlab-ci.yml has the correct tags
  • Make sure the gitlab-runner service is running
  • Make sure the machine running gitlab-runner is accessible by the Gitlab instance
• "yaml invalid"
  • Go to the Gitlab project > CI/CD
  • On the top-right portion, click the CI Lint button
  • Paste the contents of gitlab-ci.yml file and validate
• The gitlab-runner is leaving a lot of -cache- containers/volumes
  • See a discussion of this behavior here
  • Possible solutions:
    • Manually regularly run docker system prune
    • Setup a cron job docker system prune -f

      # Cleanup docker containers/volumes every 3am every monday
      0 3 * * 1 /usr/bin/docker system prune -f
      
      

DOCUMENTATION

• On Setting-Up CMake
  • Introduction to CMake by Examples
• On Setting-Up GoogleTest
  • GoogleTest Primer
  • How to start working with GTest and CMake
• On Setting-Up lcov
  • Build a C ++ Practical Unit Test Environment with GoogleTest + CMake
• On Setting-Up Gitlab CI
  • Getting started with GitLab CI
  • Installing a Gitlab Runner
  • Registering a Gitlab Runner
  • Configuring a Gitlab Runner
  • .gitlab-ci.yml Reference
• On Setting-Up Docker Registry
  • Deploy a registry server
  • Test an insecure registry