Jenkins Master (Server)

Jenkins’s server or master node holds all key configurations. Jenkins master server is like a control server that orchestrates all the workflow defined in the pipelines. For example, scheduling a job, monitoring the jobs, etc.

Jenkins Agent

An agent is typically a machine or container that connects to a Jenkins master and this agent that actually execute all the steps mentioned in a Job. When you create a Jenkins job, you have to assign an agent to it. Every agent has a label as a unique identifier.

When you trigger a Jenkins job from the master, the actual execution happens on the agent node that is configured in the job.

A single, monolithic Jenkins installation can work great for a small team with a relatively small number of projects. As your needs grow, however, it often becomes necessary to scale up. Jenkins provides a way to do this called “master to agent connection.” Instead of serving the Jenkins UI and running build jobs all on a single system, you can provide Jenkins with agents to handle the execution of jobs while the master serves the Jenkins UI and acts as a control node.

Pre-requisites

Let’s say we’re starting with a fresh Ubuntu 22.04 Linux installation. To get an agent working make sure you install Java ( same version as jenkins master server ) and Docker on it.

Note:- While creating an agent, be sure to separate rights, permissions, and ownership for jenkins users.

Task-01

Create an agent by setting up a node on Jenkins
Create a new AWS EC2 Instance and connect it to master(Where Jenkins is installed)
The connection of master and agent requires SSH and the public-private key pair exchange.
Verify its status under "Nodes" section.
You can follow this article for the same

Pre-Requisites

Master:-

install docker

install java

install jenkins

create ssh -keygen

and port should be open from security of ec2

Agent:-

install docker

install java

copy public key of master in agent .ssh/authorized_keys

Agent

Master

add credential

this is the private key of master and user name

and save it.

Come back on agent node and click on Launch it icon

Task-02

Run your previous Jobs (which you built on Day 26, and Day 27) on the new agent
Use labels for the agent, your master server should trigger builds for the agent server.

pipeline {
     agent any

     stages {
         stage('Code Fetch') {
             steps {
                 git 'https://github.com/ITAbhishekYadav/node-todo-cicd.git'
             }
         }
         stage('Build'){
             steps {
                 sh 'docker build . -t abhi/node-todo-app:latest'
             }
         }
         stage('Run'){
             steps {
                 sh 'docker run -d -p 8000:8000 abhi/node-todo-app:latest'
             }
         }
     }
 }

now check result

https://github.com/ITAbhishekYadav

...

Day 28 Task: Jenkins Agent