How to Install Jenkins on Ubuntu 20.04

In this article, We are going to perform How to Install Jenkins on Ubuntu 20.04.

Introduction

Jenkins is an free and open source automation tool which is used for continuous integration.

Prerequisites

• One Ubuntu server 20.04 LTS
• Atleast 1 GB RAM
• JDK 1.8 or Higher version is supported
• Open Port 8080

Install JDK on Ubuntu

Please follow below article to download and install Oracle JAVA 8 on Ubuntu 18.04/16.04 LTS Manually.

Download and Install Oracle Java 8 on Ubuntu 18.04/16.04 LTS

OR

We can install OpenJDK 8

sudo apt-get update

To install default JDK and JRE

sudo apt install default-jdk

sudo apt install default-jre

sudo apt install openjdk-11-jdk

java -version

openjdk version "11.0.11" 2021-04-20
OpenJDK Runtime Environment (build 11.0.11+9-Ubuntu-0ubuntu2.20.04)
OpenJDK 64-Bit Server VM (build 11.0.11+9-Ubuntu-0ubuntu2.20.04, mixed mode, sharing)

Step #1: Add Jenkins APT Repository Key

Here We are installing latest stable version of Jenkins, if you want to install older LTS version then visit Jenkins Installation page.

sudo wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -

Output:

ok

Add the Jenkins repository in system

sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > \
    /etc/apt/sources.list.d/jenkins.list'

Step #2: How to Install Jenkins on Ubuntu 20.04

Once key and repository added , update the source list

sudo apt-get update

While updating Jenkins source list if you are getting below errors.

Error: W: GPG error: https://pkg.jenkins.io/debian-stable binary/ Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 9B7D32F2D50582E6

Error: E: The repository ‘https://pkg.jenkins.io/debian-stable binary/ Release’ is not signed.

As per the above error,  above key is  missing: 9B7D32F2D50582E6.

Syntax:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <the key>

Add the missing key

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9B7D32F2D50582E6

Output:

Executing: /tmp/apt-key-gpghome.M2Ehv2EdIk/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys 9B7D32F2D50582E6

gpg: key 9B7D32F2D50582E6: 7 signatures not checked due to missing keys

gpg: key 9B7D32F2D50582E6: public key "Kohsuke Kawaguchi <[email protected]>" imported

gpg: Total number processed: 1

gpg:               imported: 1

Update the Jenkins Source list packages

sudo apt update

Now its time to Install Jenkins and its dependencies:

sudo apt-get install jenkins

error: jenkins : Depends: daemon but it is not installable

Solution:

sudo add-apt-repository universe

Step #3: Start Jenkins Service

sudo systemctl start jenkins

sudo systemctl status jenkins

Output:

● jenkins.service - LSB: Start Jenkins at boot time
   Loaded: loaded (/etc/init.d/jenkins; bad; vendor preset: enabled)
   Active: active (exited) since Tue 2019-05-11 10:18:52 IST; 22h ago
     Docs: man:systemd-sysv-generator(8)

Step #4: Add Firewall Rule

Allow port 8080/tcp in Firewall to Access Jenkins from remotely

sudo ufw allow 8080

Verify if port is enables

sudo ufw status

If you have installed Jenkins on Cloud Instance Allow the Port in Incoming or Network Security Group

Step #5: How to check Jenkins version command line in Linux

To check Jenkins version using command line in CentOS

 grep version /var/lib/jenkins/config.xml

Output:

grep version /var/lib/jenkins/config.xml

<?xml version='1.1' encoding='UTF-8'?>

  <version>2.222.1</version>

Step #6: Configure Jenkins on Ubuntu 20.04 LTS

After installation of Jenkins ,successfully running Jenkins services and we will check on browser by Jenkins default port number 8080. We can browse server IP address or domain

http://ip_address_or_domain_name:8080.

By hitting IP and Port on browser for the first time it will prompt for InitialAdminPassword. ssh server and type below command.

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

Output:

9aef30398db54a53a1a81ee86dd80726

After entering it will give some key as output. Copy and Paste in the browser and Click “Continue” .

In the above image we select “Install Suggested Plugins”,  and progress bar will start.

When the Installation get successful it will prompt for another page “Create First Admin User”.  On the below page enter username,password,Email.

In the above pic you can create new user and password or you can “Continue as admin“. After configuring everything you will prompt a new page.

Next it will ask to configure URL to access Jenkins and click on save and Finish button.

Now click on “Start using Jenkins”.  It will redirect to Jenkins Dashboard:

Finally you can see Jenkins Dashboard

With the above steps we have performed How to Install Jenkins on Ubuntu 20.04 LTS.

How to Completely Remove Jenkins from Ubuntu

Perform below steps, If you want to uninstall Jenkins from Ubuntu Ubuntu 20.04 LTS

stop the Jenkins service

sudo systemctl stop jenkins

Remove the Jenkins packages from Ubuntu 20.04

sudo apt remove jenkins -y

Remove the Jenkins cache files

sudo rm -rf /var/cache/jenkins

Remove the Jenkins config files directory

sudo rm -rf /var/lib/jenkins/

clean the yum packages

sudo apt clean all

Conclusion

In this article, We have covered How to install Jenkins on Ubuntu 20.04 LTS,  installed JDK, checked java, jenkins version and configured Jenkins.

Related Articles

• How to Install Jenkins on Ubuntu 18.04/16.04 LTS
• How to Install Jenkins on CentOS 8/RHEL 8

Reference:

• Jenkins Official Documentation