Gitlab_CICD_Sample Deployment

Gitlab CICD Stages:

build

- Create build of project.

- If it is docker project which contains dockerfile then, create docker image

- push into docker registry

 

test

- Test the created image is working fine or not

 

 deploy

- Deploy code on live server 

 

Keywords used in .gitlab-ci.yml

image

stages

script

before_script/after_script

tags

variables

cache

artifacts

only

 

Prerequisites:

Enable Gitlab runner:

Project -> settings -> CICD -> Runner -> Enable runner

Sample code:

# .gitlab-ci.yml

stages:

  - build

  - test

 

create_file:

  image: alpine:latest

  stage: build

  script:

   - echo "Building .."

   - mkdir build

   - touch build/somefile.txt

  artifacts:

    paths:

      - build/

 

test_file:

  image: alpine:latest

  stage: test

  script:

    - test -f build/somefile.txt

:

• create_file, test_fileare the jobs.
• If you not specify the image it will pull the default image alpine. 
• Inside the container the folders and file will be created.
• Container will be destroyed after one job is completed. That's why we have to use artifacts. So the build folder will be uploaded in artifacts of gitlab. 
• Then you use in another job test. You can check the logs and you will find the log “ Downloading artifacts”.
• If branch is protected then only all the variables will be supported in gitlab CI. 
• Gitlab runner will use docker image to create build. Gitlab requires some workspace where it can execute build steps and from where it can deploy the application. 
• Multiple jobs are there in gitlab-ci.yml 
• Once one job is completed. The pulled image will be cleared. 
• Build stage example with docker push. 

 

Now if you want to use variables in .gitlab-ci.yml then,

Project -> Settings -> CICD -> Variables

 

 

Sample build code for using variables inside gitlab ci and push image on docker registry 

image: docker:24.0.5

 

variables:

  DOCKER_HOST: tcp://docker:2375

  DOCKER_TLS_CERTDIR: ""

  DOCKER_DRIVER: overlay2

  QA_DEPLOY_PATH: /home/abc/docker-files/purval/frontend

  GIT_USERNAME: administrator

  GIT_PASSWORD: purval@123

  BRANCH: QA

  PROJECT_NAME: "purval_frontend"

  APP_IMAGE: docker.purval.app/purval/frontend-web:qa-$CI_COMMIT_SHORT_SHA

stages:

  - build

  - test

  - deploy

 

services:

- name: docker:24.0.5-dind

  alias: docker

 

build:

  stage: build

  script:

    - docker info

    - echo "$REGISTRY_TOKEN" | docker login -u "$REGISTRY_USER" --password-stdin "$REGISTRY_URL"

    - echo "Starting image build - qa-$CI_COMMIT_SHORT_SHA"

    - docker build -t $PROJECT_NAME:qa-$CI_COMMIT_SHORT_SHA .

    - echo "Setting up tag to image - $PROJECT_NAME:qa-$CI_COMMIT_SHORT_SHA"

    - docker tag $PROJECT_NAME:qa-$CI_COMMIT_SHORT_SHA $APP_IMAGE

    - echo "Push image to docker registry"

    - docker push $APP_IMAGE

 

Sample code for test stage: 

test:

  stage: test

  before_script:

    - apk add --no-cache curl

  script:

    - docker pull $APP_IMAGE

    - echo "Running container for testing"

    - docker run -e NODE_ENV=QA -d --name test_container -p 5300:5300 $APP_IMAGE

    - echo "Waiting for app to start...."

    - sleep 10

    - echo "Checking health endpoint...."

    - >

      if docker ps | grep -i 5300;

      then

        echo "✅ Test passed"

      else

        echo "❌ Test failed"

        docker logs test_container

        exit 1

      fi

    - docker stop test_container

    - docker rm test_container

Sample code for deploy stage:

deploy:

  stage: deploy

  before_script:

    - 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client -y )'

    - eval $(ssh-agent -s)

    - mkdir ~/.ssh

    - echo "$QA_SSH_PRIVATE_KEY" > ~/.ssh/id_rsa

    - chmod 600 ~/.ssh/id_rsa

    - echo "QA_SSH_HOST - $QA_SSH_HOST"

    - ssh-keyscan -p $QA_SSH_PORT $QA_SSH_HOST >> ~/.ssh/known_hosts

  script:

    - |

      ssh -p "$QA_SSH_PORT" -i ~/.ssh/id_rsa "$QA_SSH_USER@$QA_SSH_HOST" bash -s <<EOF

      export QA_DEPLOY_PATH="$QA_DEPLOY_PATH"

      export APP_IMAGE="$APP_IMAGE"

      export GIT_USERNAME="$GIT_USERNAME"

      export GIT_PASSWORD="$GIT_PASSWORD"

      # export COMPOSE_PROJECT_NAME="$PROJECT_NAME"

 

      echo "✅ Connected to remote server: $(hostname)"

      echo "Running your deployment script..."

 

 

      if [ -d "$QA_DEPLOY_PATH" ]; then

        echo "✅ Directory exists: $QA_DEPLOY_PATH"

        cd "$QA_DEPLOY_PATH" &&

        echo "APP_IMAGE=$APP_IMAGE" > .env

 

      

        docker-compose down &&

        sleep 2 &&

        # docker-compose up -d --build &&

        docker-compose up -d &&

        echo "✅ Deployment completed."

      else

        echo "❌ Directory does not exist: $QA_DEPLOY_PATH"

        exit -1

      fi

      EOF

 

  only:

    - QA

 

Once you push this changes in gitlab. the runners will start running the pipeline.

Gitlab -> Project -> Build -> Pipeline

 

You will get an error in deploy stage. as we have not set the private key of gitlab.

 

Generate Private key of gitlab.

 

1. Login gitlab server: 

ssh-keygen -t rsa -b 4096 -C "gitlab-ci-deploy-key"

cat .ssh/gitlab-ci-deploy-key 

 

2. Copy that Private key and add into the Gitlab CICD variables,

SSH_PRIVATE_KEY 

 

3. Copy public key of gitlab and paste into the target servers authorized_keys.

cat .ssh/gitlab-ci-deploy-key.pub

 

Paste into target server: 

cat .ssh/authorized_keys 

  

Now again commit some changes and it will work.

 

Thank you.