Jenkins Docker-in-Docker at home (II)

Today I will show you how to configure Jenkins to use the images we prepared in the previous post.

You need to launch Jenkins executing @docker-compose up -d@ in the directory where the docker-compose.yaml was created and then go to http://localhost:8080 where Jenkins is going to be running.

Configuring Jenkins

First of all, you need to install the Docker Plugin. There are multiple guides on how to do this so I will not cover this today.

Then you need to set up a Docker Cloud. Follow these instructions:

• Go to Manage Jenkins -> Configure System.
• At the bottom of the page search for the Cloud section.
• Add a new Docker cloud with the following parameters:
  • Docker Host URI: unix:///var/run/docker.sock
  • Check enabled!!.
• Next Add a Docker template with the following parameters:
  • Labels and Name to docker (or any other string).
  • Docker image: grcanosa/jenkins-ssh-slave-did:latest.
  • In container settings:
    • Check “Run container privileged”.
    • Add /var/run/docker.sock:/var/run/docker.sock:ro to container settings.
    • Add enviroment variable JENKINS_SLAVE_SSH_PUBKEY=”ssh-rsa XXXXXXXXXXX jenkins@XXXXXX”. This public key needs to be generated in the JM:
      • To get into the JM container: docker exec -it devops_jenkins bash.
      • Create .ssh dir: mkdir -p /var/jenkins_home/.ssh/
      • Create key: ssh-keygen. Remember to select /var/jenkins_home/.ssh/id_rsa as destination file.
      • The public key can be obtained by: cat /var/jenkins_home/.ssh/id_rsa.pub.

Jenkins pipeline.

Now everything is set up to launch a Jenkins pipeline in a docker container. An example of a Jenkinsfile to be used with this template is:

node('docker'){  //Same label as in the docker agent configuration.

  stage('greeting'){
     //prepare our slave container
     echo "grcanosa rulez!" 
     echo "new stage!"
  }

  stage('getting code'){
    git 'https://github.com/grcanosa/grcanosa_ci_test.git'
    GIT_COMMIT_HASH = sh (script: "git log -n 1 --pretty=format:'%H'", returnStdout: true)
  }

  stage('Building'){
      sh "docker build -t my_app ."
  }

  stage('Launching'){
      sh "docker run -d my_app"
  }