There are many executors available to implement CI/CD with GitLab Runner. However, Shell and Docker are more popular among them, and we can easily configure a repository with these runners. These runners can be chosen based on the requirements and availability of the resources. This article mainly focuses on Shell and Docker executor of C/C++ Linux application and code is written in bash script. The application can build and test using a bash script.
Shell Executor: Shell Executor is a very simple executor that helps to build the solution locally on the machine, where GitLab Runner is installed. In this case, GitLab Runner is installed on Linux Machine, so need to install the required software in the same system.
Docker Executor: It is a powerful tool that includes much software and it can be accessed by image. The advantage of this executor is that, we do not need to install any software manually, everything will be taken care of through docker and the required image will be downloaded from the docker hub. However, the disadvantageous is that this communication is blocked in some organizations due to security purposes. So, If this is the case Shell Executor is the best alternative.
Implementation of C/C++ on Shell Executor
Requirements: These are the basic software which needs to install in Linux machine. However, it can be changed based on the compilation script and need to download other software if needed. Software Description
Git This is the first requirement, to commit the changes on GitLab. It is a version control software which tracks the changing set of files cmake To build automation, testing, and packaging c/c++application, need to install cmake in Linux machine. gcc It is a compiler that needs to compile the c/c++ programs g++ It is also a compiler that needs to compile the c/c++ programs. It can be chosen based on the written script. grep Install it if the program is searching plain-text.
Path Configuration: After successful installation above, need to set the path of this installed software in the machine if it is not set. Run the below command on the machine. Variable /File Path
G++ export GCC=/usr/bin/g++ CC export CC=/usr/bin/gcc GREP export GREP=/usr/bin/grep Permission Give Permission to script before it run: the chmod -R 777 * .gitlab-ci.yml This file should be inside root directory of the project which contains all the CI/CD configuration including software and script path. Here, you can mention how this repository should run. Before adding this file to the root directory, should check it is a valid yml file or not.
GitLab Runner Set Up: Follow the below steps to download and configure the GitLab Runner.
1. Download GitLab Runner on Linux Machine using the following command
sudo curl -L --output /usr/local/bin/gitlab-runner https://gitlab-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-runner-linux-amd64
2. Give it permissions for execution using the following command
sudo chmod +x /usr/local/bin/gitlab-runner
3. Create a GitLab CI using the following command
sudo useradd --comment 'GitLab Runner' --create-home gitlab-runner --shell /bin/bash
4. Install and run as service using the following command
sudo gitlab-runner install --user=gitlab-runner --working-directory=/home/gitlab-runner
5. Start GitLab Runner using the following command
sudo gitlab-runner start
6. Stop the GitLab Runner before registering the repository
sudo gitlab-runner stop
7. Once GitLab Runner is successfully stopped enter the following command in the terminal for repository registration.
sudo gitlab-runner register
8. When you do repository registration with GitLab Runner, the below questions have to answer.
- Enter your GitLab instance URL: It can be different with each organization and the format will be like http://gitlab.example.com
- Path: Go to GitLab Account → Select repository which you want to register with runner → Settings → CI/CD → Expand Runner
- Enter the gitlab-ci token for this runner: It will be a unique token of each project which will need while registration and it can be found Path: Go to GitLab Account → Select repository which you want to register with runner → Settings → CI/CD → Expand Runner
- Enter the gitlab-ci description for this runner: Put Runner name(any name), which will help you to remember that which runner’ is running
- Enter the gitlab-ci tags for this runner: It is optional if you want to start GitLab runner when a specific tag is available in yml file.
- Enter the executor: There will be a list of several executors, and type shell(as GitLab Runner will run our system)
9. After successful registration, start the GitLab Runner using the following command.
sudo gitlab-runner start
10. To verify that GitLab Runner has registered the respective repository and the runner has been started. Go to GitLab Account → Select repository which you want to register with runner → Settings → CI/CD → Expand Runner, There will be green color circle will be available and displaying message will be Runners activated for this project. Note: If the circle is gray, it means the runner has not started and starts again.
Linux GitLab Runner Commands
Follow some more GitLab Runner commands to familiarize yourself. Command Description
sudo gitlab-runner register Register the project with GitLab Runner sudo gitlab-runner start Start the runner sudo gitlab-runner stop Stop the runner sudo gitlab-runner status To know the status of gitlab-runner sudo gitlab-runner unregister –name test-runner Unregister the Runner of a project and replace the test-runner with your runner name and this name can be found inside the config.toml file (where your gitlab-runner ) available. sudo gitlab-runner unregister –url http://gitlab.example.com/ –token t0k3n Remove Runner by URL and token sudo gitlab-runner unregister –all-runners To unregister All Runners sudo gitlab-runner restart This command stops and then starts the GitLab Runner service sudo gitlab-runner uninstall This command stops and uninstalls the GitLab Runner from being run as a service sudo gitlab-runner exec To see a list of available executors, run sudo gitlab-runner –help Check a recent list of commands by executing sudo gitlab-runner run –help Can see the name of the environment variable sudo gitlab-runner –debug To run a command in debug mode sudo gitlab-runner exec shell To see a list of all available options for the shell executor, run
.gitlab-ci.yml_ shell Executor:
Below is the content of .gitlab-ci.yml on shell executor mode. However, change it if needed.
stages: - build - test build_job: stage: build only: - master script: - cd sourcecode - export G++=/usr/bin/g++ //if not set manually path of g++ - export GCC=/usr/bin/gcc //if not set manually path of gcc - chmod -R 777 * - ./BuildPackage.sh - pwd artifacts: expire_in: 365 days //save the binary which needed while test the application, and it can be downloaded from GitLab paths: - sourcecode/binaryfolder_name // save the binary test_job: stage: test only: - master script: - pwd - cd testdir //go to test directory for run the test case script - chmod -R 777 * - ./tests.sh dependencies: - build_job - build_job
Implementation of C/C++ on Docker Executor: There is no need to install any software manually, everything will be taken from the docker container. However, you can install the required software inputting the name in yml file and also can export the path. To run the gitlab runner on docker executor mode, Go to GitLab Runner Set-Up(above), and select docker instead of shell.
.gitlab-ci.yml_ Docker Executor:
Below is the content of .gitlab-ci.yml on docker executor mode. However, change it if needed.
image: ubuntu:latest stages: - build - test before_script: - echo "Before script install this on ubuntu image " - apt-get update && apt-get -y install cmake && apt-get -y install gcc && apt-get -y install g++ build_job: stage: build only: - master script: - cd sourcecode - export G++=/usr/bin/g++ //if not set manually path of g++ - export GCC=/usr/bin/gcc //if not set manually path of gcc - chmod -R 777 * - ./BuildPackage.sh - pwd artifacts: expire_in: 365 days //save the binary which needed while test the application, and it can be downloaded from GitLab paths: - sourcecode/binaryfolder_name // save the binary test_job: stage: test only: - master script: - pwd - cd testdir //go to test directory for run the test case script - chmod -R 777 * - ./tests.sh dependencies: - build_job