Jenkins #

Install #

Docker Compose #

• How to Install and Run Jenkins With Docker Compose

1. Make docker-compose.yml
   https://hub.docker.com/_/jenkins

version: '3.8'
services:
  jenkins:
    container_name: jenkins
    image: jenkins/jenkins:latest
    privileged: true
    ports:
      - 8080:8080
    volumes:
      - ./jenkins_home:/var/jenkins_home

2. Run the following.

$ docker-compose up -d

3. Confirm the admin initial password.

$ docker logs jenkins | less
*************************************************************
*************************************************************
*************************************************************
 
Jenkins initial setup is required. An admin user has been created and a password generated.
Please use the following password to proceed to installation:
 
XXXXXXXXXXXXXXXXXXXXXXXXXXX (You can see the password here)
 
This may also be found at: /var/jenkins_home/secrets/initialAdminPassword
 
*************************************************************
*************************************************************
*************************************************************

or

$ docker container ls
$ docker container exec -it jenkins sh
$ cat /var/jenkins_home/secrets/initialAdminPassword

4. Access http://localhost:8080 .
   • Unlock Jenkins page.
     • Enter the admin initial password in Administrator passwprd .
     • Click Continue .
   • Customize Jenkins page.
     • Click Install suggested plugins (if you are a beginner).
   • Create First Admin User page.
     • Click Skip and continuue as admin .

CentOS #

sudo wget --no-check-certificate -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo
sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key
sudo yum install -y jenkins

Jenkins Agent #

Generate SSH keys #

1. Generate the private key and the public key.

$ ssh-keygen -t ed25519 -f jenkins_agent
Generating public/private ed25519 key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

$ ls -al jenkins_agent*

• jenkins_agent (private key)
• jenkins_agent.pub (public key)

2. Confirm the strength.

$ ssh-keygen -l -f jenkins_agent
256 SHA256:XXXXXXXXXXXXXX XXXXXX@XXXXXX (ED25519)

Set the private key in Jenkins #

1. Access http://localhost:8080 and login.
2. Move to Dashboad > Manage Jenkins > Manage Credentials .
3. Click Jenkins under Stores scoped to Jenkins .
4. Click Global credentials (unrestricted) .
5. Click Add Credentials in left menu.
6. Set options.
   • Select SSH Username with private key .
   • Select System (Jenkins and nodes only) from Scope .
     • This means the key can NOT be used for jobs.
   • Enter jenkins_agent for ID .
   • Enter Jenkins agent key for Description .
   • Enter jenkins for Username .
   • Select Enter directly of Provate key .
   • Click Add .
   • Enter the contents of the private key. Your can see it by executing following cat jenkins_agent .
   • Click OK .

Set the public key #

1. Add agent container to docker-compose.yml .
   • https://hub.docker.com/r/jenkins/ssh-agent
   • Do NOT enclose the contents of the public key in quotes.

version: '3.8'
services:
  jenkins:
    container_name: jenkins
    image: jenkins/jenkins:latest
    privileged: true
    ports:
      - 8080:8080
    volumes:
      - ./jenkins_home:/var/jenkins_home
agent:
  image: jenkins/ssh-agent:jdk11
  privileged: true
  container_name: agent
  expose:
    - 22
  environment:
    - JENKINS_AGENT_SSH_PUBKEY=ssh-ed25519 XXXXXXXXXXXXXX XXXXXX@XXXXXX (Please write the public key here)

2. Restart docker compose.

$ docker-compose down
$ docker-compose up -d

Add new node #

1. Access http://localhost:8080 and login.
2. Move to Dashboad > Manage Jenkins > Manage Nodes and Clouds .
3. Click New Node in the menu on the left.
   • Enter jenkins_agent in Name .
   • Select Permanent Agent in Type .
   • Click Create .
   • Enter /home/jenkins/agent in Remote root directory .
   • Select Use this node as much as possible in Usage .
   • Select Launch agents via SSH in Launch method .
   • Select Jenkins(Jenkins Agent Key) in Credentials.
   • Select Non verifying Verification Strategy in Host Key Verification Strategy .
   • Click Advanced on the right.
   • Enter /usr/local/openjdk-11/bin/java in JavaPath .
   • Click Save .
4. Click jenkins-agent in node list.
5. Click Log in the menu on the left. .
6. It is OK if you see Agent successfully connected and online .

Plugin #

1. Access http://localhost:8080 and login.
2. Move to Dashboad > Manage Jenkins > Manage Plugins .
3. Click Installed .
   • Confirm that the following are already installed if you choose Install suggested plugins previous step.
     • Mailer
     • Build With Parameter
4. Click Available .
   • Find and select the following using a search box.
     • Rebuilder
     • Blue Ocean
     • Office 365 Connector
     • Maven Integration
   • Install without restart

Job #

Pipeline #

• Jenkins Pipline Syntax

e.g.

pipeline {
    agent any
    stages {
        stage('Hello') {
            steps {
                echo 'Hello'
            }
        }
        stage('World(SKIP)') {
            when {
                expression { params.SKIP == false }
            }
            steps {
                echo 'World'
            }
        }
    }
}