How to Install & Set Up Jenkins

Prerequisites

• ✓A host with 2 GB+ RAM for the controller (agents doing the actual building want more, depending on what they build)
• ✓Java 17 or 21 (installed below on Ubuntu)

Controller, agents, and jobs — how Jenkins is put together

The Jenkins process you install below is the controller: it serves the web UI, stores configuration and build history, and schedules work — but by default it also runs builds on itself via a 'built-in node', which is fine for a lab and something you'll want to change once real traffic shows up (see the agent section below).

Almost everything past the core is a plugin — SCM integrations, notification channels, cloud agent provisioners, and the Pipeline engine itself all arrive as plugins, which is why the initial setup wizard spends most of its time installing them.

A job is a unit of work. Freestyle jobs configure a build through UI form fields and were the original Jenkins model; Pipeline jobs read a Jenkinsfile — a script, checked into your repo alongside the code it builds — which is the standard approach today because the build definition is versioned, reviewable, and portable between Jenkins instances.

Install Jenkins on Ubuntu (LTS repo)

sudo apt update
sudo apt install -y fontconfig openjdk-17-jre
sudo wget -O /etc/apt/keyrings/jenkins-keyring.asc https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key
echo "deb [signed-by=/etc/apt/keyrings/jenkins-keyring.asc] https://pkg.jenkins.io/debian-stable binary/" | sudo tee /etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt-get update
sudo apt-get install -y jenkins
sudo systemctl enable --now jenkins

Install Jenkins on RHEL, CentOS Stream, or Fedora (LTS repo)

sudo wget -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-2023.key
sudo dnf install -y fontconfig java-17-openjdk jenkins
sudo systemctl enable --now jenkins

Alternative — run Jenkins in Docker

docker run -d --name jenkins \
  -p 8080:8080 -p 50000:50000 \
  -v jenkins_home:/var/jenkins_home \
  jenkins/jenkins:lts

Unlock and verify

Browse to http://your-server:8080 and paste the initial admin password to get past the setup wizard's unlock screen. Take the wizard's 'Install suggested plugins' option unless you have a specific reason not to — it covers Git, Pipeline, and credentials support, which you'll want immediately.

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

Write your first Pipeline

Create a Jenkinsfile at the root of a repository, then point a new Pipeline job at that repo — Jenkins reads the file straight from source control on every run.

pipeline {
    agent any

    stages {
        stage('Build') {
            steps {
                sh 'npm ci'
                sh 'npm run build'
            }
        }
        stage('Test') {
            steps {
                sh 'npm test'
            }
        }
        stage('Deploy') {
            when { branch 'main' }
            steps {
                sh './deploy.sh'
            }
        }
    }

    post {
        failure {
            echo 'Build failed — check the console log.'
        }
    }
}

Attach a build agent

Once builds need isolation, more capacity, or a specific toolchain the controller doesn't have, add a separate agent node rather than building on the controller. Manage Jenkins → Nodes → New Node walks you through it and, for an inbound (JNLP) agent, hands you a ready-to-run command like the one below to execute on the agent machine.

java -jar agent.jar -url http://your-server:8080/ \
  -secret AGENT_SECRET -name my-agent -workDir "/home/jenkins/agent"

Keep secrets out of the Jenkinsfile

Never hardcode credentials in a pipeline script that's checked into a repo. Add them once under Manage Jenkins → Credentials, then reference the credential ID from the Jenkinsfile — Jenkins injects the real value at run time and masks it in the console log.

withCredentials([usernamePassword(credentialsId: 'docker-hub', usernameVariable: 'USER', passwordVariable: 'PASS')]) {
    sh 'docker login -u "$USER" -p "$PASS"'
}

Related Guides