First Experience with GitLab's CI/CD Pipeline

CI/CD#

I won't go into the concept and explanation of CI/CD here, you can read this article for more information.

Why choose GitLab's pipeline#

The reason is simple, the company's code is hosted on GitLab, and GitLab's free quota seems to be quite high.
The reason for not choosing Jenkins is also simple, the UI is outdated, and although it has many features, it also consumes a lot of resources.
If you are a beginner, maybe Drone is also a good choice? After all, it has a visual interface and consumes very little resources.

Register a runner#

If you just want to test or try it out, you can use a shared runner without registering.
But if you want to deploy it on your own server, you must use a registered runner.
There are generally two ways to register a runner:
docker

docker run -d --name gitlab-runner --restart always \\n  -v /home/jk/docker/gitlabRunner/config:/etc/gitlab-runner \\n  -v /var/run/docker.sock:/var/run/docker.sock \\n  gitlab/gitlab-runner:latest

Note that the runner registered using the docker method cannot deploy new containers at the host level. DIND (Docker in Docker) is like adding an extra layer, so it is only suitable for building, not for deployment.
shell

sudo curl -L --output /usr/local/bin/gitlab-runner https://gitlab-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-runner-linux-amd64
sudo chmod +x /usr/local/bin/gitlab-runner
sudo useradd --comment 'GitLab Runner' --create-home gitlab-runner --shell /bin/bash
sudo gitlab-runner install --user=gitlab-runner --working-directory=/home/gitlab-runner
sudo gitlab-runner start
sudo gitlab-runner register --url https://gitlab.com/ --registration-token {gitlab registration token}
sudo gpasswd -a gitlab-runner docker

The shell mode can pull and run docker images on the host machine, suitable for deploying services.
For more detailed installation instructions, you can refer to the official documentation.

Create a configuration file#

You can create a configuration file in the Build ---> CI/CD ---> Pipeline Editor of your GitLab project, or use the official configuration template.

The configuration file is named .gitlab-ci.yml and must be placed in the root directory of the project.

.gitlab-ci.yml has its specified keywords and format. You can refer to the official syntax documentation for more information.
Here are some commonly used keywords:

Keyword	Description	Usage
image	Specify the Docker image required for the pipeline	`image: docker:latest`
services	Specify additional images	`services:- name: docker:dind`
variables	Define global variables	`variables:PORT: 9005`
stages	Define stages of the pipeline	`stages:- build - docker-build`
tags	Specify the runner to be used for this stage	`tags: - shell-node`
artifacts	Job artifacts, using the build command will generate files, this keyword can save the built files	`artifacts:paths:- target/jk_testing-1.0-SNAPSHOT.jar`
script	Specify the command script to be run in this stage	`script:- mvn clean install`

Of course, GitLab also provides a considerable number of variables for use.
For example, $CI_COMMIT_SHORT_SHA represents the commit's short SHA, and you can also use custom variables in variables.
You can check all the variables in the official documentation.

I highly recommend using a Dockerfile to package your project into a Docker image, which will make it easier to manage and deploy.

Example#

Below, I will use a spring boot project to explain the configuration file to you. I will try to add comments.

# Specify the Docker image required for the pipeline
image: docker:latest

# Specify additional images
services:
- name: docker:dind

# Define variables
variables:
  PORT: 9005
  APPLICATION_NAME: test


# Define stages of the pipeline
stages:
  - build
  - docker-build
  - deploy
  - notify


# Build stage: execute Maven build
build:
  image: maven:3.6.3-openjdk-8
  stage: build
  # Define the script to be executed
  script:
    - mvn clean install
  artifacts:
    paths:
    - target/jk_testing-1.0-SNAPSHOT.jar

# Docker build stage: build Docker image and push it to the image registry
docker-build:
  stage: docker-build
  script:
    - docker build -t $APPLICATION_NAME .
    - docker tag $APPLICATION_NAME $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA

# Deploy stage: rolling update of the image
deploy:
  stage: deploy
  # Specify a shell runner
  tags:
    - shell-node
  script:
    # Define multiple scripts
    # Stop the container with the name containing "test", then remove the container and image
    # Then pull the latest image from the image registry and run it
    - >
      if [[ $(docker ps -q -f name=$APPLICATION_NAME) ]]; then
      docker stop $APPLICATION_NAME 2>/dev/null;
      docker rm $APPLICATION_NAME 2>/dev/null;
      docker images | grep test | awk '{print $3}' | xargs -I {} docker rmi {};
      fi
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA
    - docker run -d -p $PORT:9004 --name $APPLICATION_NAME $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA

# Notification message when the build fails
notifyFailWeChat:
  stage: notify
  script:
    - apk add curl
    - curl 'https://qyapi.weixin.qq.com/cgi-bin/webhook/send?key= {WeChat robot token}' -H 'Content-Type:application/json' -d "{\"msgtype\":\"markdown\",\"markdown\":{\"content\":\"Mini Program project build result: <font color=\\"warning\\">Failed</font>\n>This build was triggered by: $GITLAB_USER_NAME\n>Project name: $CI_PROJECT_NAME\n>Commit SHA: $CI_COMMIT_SHA\n>Commit message: $CI_COMMIT_MESSAGE\n>Build branch: $CI_COMMIT_BRANCH\n>Pipeline URL: [$CI_PIPELINE_URL]($CI_PIPELINE_URL)\"}}"
  # Only run on the master branch
  only:
    - master
  # Specify when to execute, in this case, it will be executed when the pipeline build fails
  when: on_failure

# Notification message when the build succeeds
notifySuccessWeChat:
  stage: notify
  script:
    - apk add curl
    - curl 'https://qyapi.weixin.qq.com/cgi-bin/webhook/send?key= {WeChat robot token}' -H 'Content-Type:application/json' -d "{\"msgtype\":\"markdown\",\"markdown\":{\"content\":\"Mini Program project build result: <font color=\\"info\\">Success</font>\n>This build was triggered by: $GITLAB_USER_NAME\n>Project name: $CI_PROJECT_NAME\n>Commit SHA: $CI_COMMIT_SHA\n>Commit message: $CI_COMMIT_MESSAGE\n>Build branch: $CI_COMMIT_BRANCH\n>Pipeline URL: [$CI_PIPELINE_URL]($CI_PIPELINE_URL)\"}}"
  only:
    - master
  when: on_success