Installing and configuring Jenkins on Ubuntu
You’ll learn how to pull the latest Jenkins build straight from its own repository, hook up a proper Java runtime, get the service running right away, and finish with the admin‑password wizard that turns the server into a fully‑functional CI engine.
Prerequisites: What you need before you start
- A fresh or existing Ubuntu 22.04+ machine (or WSL if that’s your playground).
- Sudo privileges – Jenkins needs to write to /var/lib/jenkins and bind to port 8080.
- Internet access for downloading packages.
Step 1: Add the official Jenkins repository
wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add - sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
The Ubuntu default repo ships an old Jenkins (1.647 or older). That version can’t run newer plugins and will leave you staring at a broken build queue. By pointing to the official source, you get the latest LTS release that stays in sync with the plugin ecosystem.
Step 2: Install OpenJDK 11 (or higher)
sudo apt update sudo apt install -y openjdk-17-jdk
Jenkins is a Java application, and it insists on a recent JDK. A quick check:
java -version # should show 17 or newer
If you already have Java installed from somewhere else, skip the install but still verify the version.
Step 3: Pull down Jenkins
sudo apt install jenkins
That one command does everything: downloads the package, resolves dependencies, and registers the service. If your machine is a little slow, you might want to watch the download progress; it’s a 70 MB file on a 10 Mbps line.
Step 4: Start Jenkins and enable auto‑start
sudo systemctl start jenkins sudo systemctl enable jenkins
You can confirm the service is live with:
systemctl status jenkins
If you see “active (running)”, you’re good. If not, read the journal:
journalctl -u jenkins --since="5 minutes ago"
Step 5: Grab the initial admin password
Jenkins creates a random password on first launch and stores it in /var/lib/jenkins/secrets/initialAdminPassword. Get it with:
sudo cat /var/lib/jenkins/secrets/initialAdminPassword
Copy that string. It’s only valid the first time you hit the web UI.
Step 6: Complete the web‑UI wizard
Open your browser to http://<your-server-ip>:8080.
1. Paste the admin password.
2. Let Jenkins install suggested plugins – if you’re on a server that will run heavy jobs, skip “Git” and “Maven Integration”; I’ve seen people get bogged down installing dozens of plugins they never touch.
3. Create your first admin user (or keep the default if you prefer).
That’s it: Jenkins is up, running, and ready to accept build jobs.
Common pitfalls and how to dodge them
- Firewall blocking 8080 – sudo ufw allow 8080/tcp.
- Java version mismatch – If you see “Could not find java.lang.Object”, Jenkins can’t start. Re‑install the JDK or set JAVA_HOME correctly.
- Old packages lingering – Running apt update && apt upgrade after adding the repo ensures you’re on the LTS build, not a stale release.
Real‑world tweak I learned last month
When I first installed Jenkins on an older 64‑bit VM for a hobby project, the default Ubuntu repo gave me 1.646. The plugin I needed (the “Docker Pipeline” plugin) refused to load because it required Java 8 but bundled a version of Docker that only worked with newer Java. Switching to the official repo resolved both issues in under ten minutes.
