Using docker with Jenkins Pipelines

Objectives:

• You will learn how to prepare Jenkins environment to build with a docker agent
• Refactor Jenkinsfile with docker based agents
• Build and test nodejs, maven and python applications with docker

Steps:

• Read : Using Docker with Pipeline
• Install docker inside jenkins container
• Restart Jenkins Container with Docker
• Refactor the Jenkinsfile for worker app using the following reference

Test building with Docker Agent

Create a test pipeline to run a job with docker agent

Create docker-pipe-01 pipeline job in your jenkins. On the configuration page, add the following test code in jenkins pipeline script, save the configuration and build it.

pipeline {
    agent {
        docker { image 'node:7-alpine' }
    }
    stages {
        stage('Test') {
            steps {
                sh 'node --version'
            }
        }
    }
}

Run the job, and check if that worked? If not, proceed with the next section to setup docker.

Install Docker inside Jenkins Container

Exec into jenkins container as root,

docker exec -it -u root jenkins bash

Run the following set of commands to install docker client and prepare Jenkins to launch containers from,

apt-get update

apt-get install -yq \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg2 \
    software-properties-common

curl -fsSL https://download.docker.com/linux/debian/gpg |  apt-key add -


add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/debian \
   $(lsb_release -cs) \
   stable"

apt-get update

apt-get install -yq  docker-ce docker-ce-cli containerd.io

usermod -a -G docker jenkins

chmod 777 /var/run/docker.sock


curl -L "https://github.com/docker/compose/releases/download/1.24.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

chmod +x /usr/local/bin/docker-compose

Finally, check if docker client is working and exit from the container.

docker ps
exit

Restart jenkins containers so that it takes effect with the new configurations,

docker restart jenkins

Exec into jenkins container again, this time as jeknins user and validate,

docker exec -it jenkins bash

docker ps

If you see the list of containers, docker client is been installed and configured ok.

file: worker/Jenkinsfile

pipeline{

    agent{
       docker{
         image 'maven:3.6.1-jdk-8-slim'
         args '-v $HOME/.m2:/root/.m2'
       }

    }


    stages{
        stage('build'){
            steps{
                echo 'building worker app'
                dir('worker'){
                  sh 'mvn compile'
                }
            }
        }
        stage('test'){
            steps{
                echo 'running unit tests on worker app'
                dir('worker'){
                  sh 'mvn clean test'
                }
            }
        }
        stage('package'){
            steps{
                echo 'packaging worker app into a jarfile'
                dir('worker'){
                  sh 'mvn package -DskipTests'
                  archiveArtifacts artifacts: '**/target/*.jar', fingerprint: true
                }
            }
        }
    }

    post{
        always{
            echo 'the job is complete'
        }

    }

}

Exercise

• Refactor the result/Jenkinsfile for nodeJS app
• Create a Jenkinsfile and a multi branch pipeline for vote python app