Jenkins Master (Server)

Jenkins’s server or master node holds all key configurations. The 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 Slave (Node)

An agent is typically a machine or container that connects to a Jenkins master and this agent executes 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:

Master:

Install java - sudo apt install openjdk-11-jre

Install jenkins - sudo apt install jenkins

Create ssh -keygen

Port should be open from security of virtual machine

Slave:

Install java

Copy public key of master in agent .ssh/authorized_keys

Check whether your master server Jenkins is running or not

Connect master to slave

Click - Manage Jenkins - Manage nodes and clouds - New node add

Give a node name and tick on permanent agent and create

Give description and Remote root directory as "/home/ibrahims/jenkins"

Give the label "dev" and Usage to " use this node much as possible" and Launch method to " Launch agents via SSH " and copy Host as slave server virtual machine IP address like this and paste it there.

Generate the SSH in slave nodes ssh-keygen