How To Install Jenkins on Ubuntu 22.04

 

Prerequisites

To follow this tutorial, you will need

• One Ubuntu 22.04 server configured with a non-root sudo user and firewall by following the Ubuntu 22.04 initial server setup guide. We recommend starting with at least 1 GB of RAM. Visit Jenkins’s “Hardware Recommendations” for guidance in planning the capacity of a production-level Jenkins installation. 

  Oracle JDK 11 installed.

   

  Step 1 — Installing Jenkins

  The version of Jenkins included with the default Ubuntu packages is often behind the latest available version from the project itself. To ensure you have the latest fixes and features, use the project-maintained packages to install Jenkins.

  First, add the repository key to your system:

  $ wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key |sudo gpg --dearmor -o /usr/share/keyrings/jenkins.gpg

  The gpg --dearmor command is used to convert the key into a format that apt recognizes.

  Next, let’s append the Debian package repository address to the server’s sources.list:

  $ sudo sh -c 'echo deb [signed-by=/usr/share/keyrings/jenkins.gpg] http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'

  The [signed-by=/usr/share/keyrings/jenkins.gpg] portion of the line ensures that apt will verify files in the repository using the GPG key that you just downloaded.

  After both commands have been entered, run apt update so that apt will use the new repository.

  $ sudo apt update

  Finally, install Jenkins and its dependencies:

  $ sudo apt install jenkins

  Now that Jenkins and its dependencies are in place, we’ll start the Jenkins server.

  Step 2 — Starting Jenkins

  now that Jenkins is installed, start it by using systemctl:

  sudo systemctl start jenkins.service

  Since systemctl doesn’t display status output, we’ll use the status command to verify that Jenkins started successfully:

  $ sudo systemctl status jenkins 

  If everything went well, the beginning of the status output shows that the service is active and configured to start at boot:

  Output
  ● jenkins.service - Jenkins Continuous Integration Server
       Loaded: loaded (/lib/systemd/system/jenkins.service; enabled; vendor preset: enabled)
       Active: active (running) since Mon 2022-04-18 16:07:28 UTC; 2min 3s ago
     Main PID: 88180 (java)
        Tasks: 42 (limit: 4665)
       Memory: 1.1G
          CPU: 46.997s
       CGroup: /system.slice/jenkins.service
               └─88180 /usr/bin/java -Djava.awt.headless=true -jar /usr/share/java/jenkins.war --webroot=/var/cache/jenkins/war --httpPort=8080 

  Now that Jenkins is up and running, adjust your firewall rules so that 
  you can reach it from a web browser to complete the initial setup.

  Step 3 — Opening the Firewall

  To set up a UFW firewall, visit Initial Server Setup with Ubuntu 22.04, Step 4- Setting up a Basic Firewall. By default, Jenkins runs on port 8080. Open that port using ufw:

  $ sudo ufw allow 8080

  Note: If the firewall is inactive, the following commands will allow OpenSSH and enable the firewall:

  $ sudo ufw allow OpenSSH

  $ sudo ufw enable

  Check ufw’s status to confirm the new rules:

  You’ll notice that traffic is allowed to port 8080 from anywhere: 

  Output
  Status: active
  
  To                         Action      From
  --                         ------      ----
  OpenSSH                    ALLOW       Anywhere
  8080                       ALLOW       Anywhere
  OpenSSH (v6)               ALLOW       Anywhere (v6)
  8080 (v6)                  ALLOW       Anywhere (v6)

  With Jenkins installed and a firewall configured, you have completed the installation stage and can continue with configuring Jenkins.

  Step 4 — Setting Up Jenkins

  To set up your installation, visit Jenkins on its default port, 8080, using your server domain name or IP address: http://your_server_ip_or_domain:8080

  You should receive the Unlock Jenkins screen, which displays the location of the initial password:

   

  In the terminal window, use the cat command to display the password:

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

  Copy the 32-character alphanumeric password from the terminal and paste it into the Administrator password field, then click Continue.

  The next screen presents the option of installing suggested plugins or selecting specific plugins:

   

   
  

  We’ll click the Install suggested plugins option, which will immediately begin the installation process.

  
  

   

    When the installation is complete, you’ll be prompted to set up the 
  first administrative user. It’s possible to skip this step and continue 
  as admin using the initial password from above, but we’ll take a moment to create the user.

   

  Enter the name and password for your user:

  
  

   

   

  You’ll receive an Instance Configuration page that will ask you to confirm the preferred URL for your Jenkins instance. Confirm either the domain name for your server or your server’s IP address:

  
  

   

   After confirming the appropriate information, click Save and Finish. You’ll receive a confirmation page confirming that “Jenkins is Ready!”:

  
  

   

  Click Start using Jenkins to visit the main Jenkins dashboard:

  
  

   

  At this point, you have completed a successful installation of Jenkins.

Initial Server Setup with Ubuntu 22.04

 Introduction

When you first create a new Ubuntu 22.04 server, you should perform some important configuration steps as part of the initial setup. These steps will increase the security and usability of your server and will give you a solid foundation for subsequent actions.
Step 1 — Logging in as root

To log into your server, you will need to know your server’s public IP address. You will also need the password or the private key for the root user’s account if you installed an SSH key for authentication. If you have not already logged into your server, you may want to follow our guide on how to Connect to Droplets with SSH, which covers this process in detail.

If you are not connected to your server currently, log in as the root user using the following command. Substitute the highlighted your_server_ip portion of the command with your server’s public IP address:

ssh root@your_server_ip

Accept the warning about host authenticity if it appears. If your server uses password authentication, provide your root password to log in. If you use an SSH key that is passphrase protected, you may need to enter the passphrase the first time you use the key each session. If this is your first time logging into the server with a password, you may also need to change the root password. Follow the instructions to change the password if you receive a prompt.

About root

The root user is the administrative user in a Linux environment with elevated privileges. Because of the heightened privileges of the root account, you are discouraged from using it regularly. The root account can make very destructive changes, even by accident.

The next step is setting up a new user account with reduced privileges for day-to-day use. Later, we’ll show you how to temporarily gain increased privileges for the times when you need them.

Step 2 — Creating a New User

Once you log in as root, you’ll be able to add the new user account. In the future, we’ll log in with this new account instead of root.

This example creates a new user called sammy, but you should replace that with a username that you like:

# adduser sammy 

You will be asked a few questions, starting with the account password.

Enter a strong password and, optionally, fill in any of the additional information if you would like. This information is not required, and you can press ENTER in any field you wish to skip.

Step 3 — Granting Administrative Privileges

Now you have a new user account with regular account privileges. However, you will sometimes need to perform administrative tasks as the root user.

To avoid logging out of your regular user and logging back in as the root account, you can set up what is known as superuser or root privileges for your user’s regular account. These privileges will allow your normal user to run commands with administrative privileges by putting the word sudo before the command.

To add these privileges to your new user, you will need to add the user to the sudo system group. By default on Ubuntu 22.04, users who are members of the sudo group are allowed to use the sudo command.

As root, run this command to add your new user to the sudo group (substitute the highlighted sammy username with your new user):

# usermod -aG sudo sammy

You can now type sudo before commands to run them with superuser privileges when logged in as your regular user.

Step 4 — Setting Up a Firewall

Ubuntu 22.04 servers can use the UFW firewall to ensure only connections to certain services are allowed. You can set up a basic firewall using this application.

Applications can register their profiles with UFW upon installation. These profiles allow UFW to manage these applications by name. OpenSSH, the service that allows you to connect to your server, has a profile registered with UFW.

You can examine the list of installed UFW profiles by typing:

#ufw app list

Output
Available applications:
  OpenSSH

 You will need to make sure that the firewall allows SSH connections so that you can log into your server next time. Allow these connections by typing:

# ufw allow OpenSSH

 

Now enable the firewall by typing:

# ufw enable

Type y and press ENTER to proceed. You can see that SSH connections are still allowed by typing:

# ufw status

Output
Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere
OpenSSH (v6)               ALLOW       Anywhere (v6)

Tthe firewall is currently blocking all connections except for SSH.
 If you install and configure additional services, you will need to 
adjust the firewall settings to allow the new traffic into your server. 
You can learn some common UFW operations in our UFW Essentials guide.

Step 5 — Enabling External Access for Your Regular User

Now that you have a regular user for daily use, you will need to make sure that you can SSH into the account directly.

Configuring SSH access for your new user depends on whether your server’s root account uses a password or SSH keys for authentication.

If the root Account Uses Password Authentication

If you logged in to your root account using a password then password authentication is enabled for SSH. You can SSH to your new user account by opening up a new terminal session and using SSH with your new username:

$ ssh sammy@your_server_ip

After entering your regular user’s password, you will be logged in. Remember, if you need to run a command with administrative privileges, type sudo before it like this:

$ sudo command_to_run

You will receive a prompt for your regular user’s password when using sudo for the first time each session (and periodically afterward).

To enhance your server’s security, we strongly recommend setting up SSH keys instead of using password authentication. Follow our guide on setting up SSH keys on Ubuntu 22.04 to learn how to configure key-based authentication.

If the root Account Uses SSH Key Authentication

If you logged in to your root account using SSH keys, then password authentication is disabled for SSH. To log in as your regular user with an SSH key, you must add a copy of your local public key to your new user’s ~/.ssh/authorized_keys file.

Since your public key is already in the root account’s ~/.ssh/authorized_keys file on the server, you can copy that file and directory structure to your new user account using your current session.

The simplest way to copy the files with the correct ownership and permissions is with the rsync command. This command will copy the root user’s .ssh directory, preserve the permissions, and modify the file owners, all in a single command. Make sure to change the highlighted portions of the command below to match your regular user’s name: