How to install Jenkins on CentOS

Jenkins is an open-source automation server that helps to automate different types of tasks such as building, testing, and deploying software ( wich is part of the CI/CD process). In this tutorial, we will learn how to install it on CentOS 7.9.

Prerequisites

Before we start installing ou automation server, we need to ensure that the following prerequisites are met :

-A CentOS 7.9 server with a non-root user with sudo privileges.

-Java 8 or later version should be installed on the server.

In this tutorial we will discuss about installing OpenJDK 11.

Installing OpenJDK 11 :

as root, run the command bellow to install java 11 :

[root@jenkins ~]# yum install java-11-openjdk

Once the installation is complete, check the version :

[root@jenkins ~]# java --version
openjdk 11.0.19 2023-04-18 LTS
OpenJDK Runtime Environment (Red_Hat-11.0.19.0.7-1.el7_9) (build 11.0.19+7-LTS)
OpenJDK 64-Bit Server VM (Red_Hat-11.0.19.0.7-1.el7_9) (build 11.0.19+7-LTS, mixed mode, sharing)

Now that’s our java is installed, let’s install automation server :

Install Jenkins

We need to set up the Jenkins repository. just follow the steps bellow :

Step 1: Run the following commande to download the repository file :

[root@jenkins ~]# wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat-stable/jenkins.repo

This command downloads the repository file and place it on /etc/yum.repos.d/. Let’s take a look on this file :

[root@jenkins ~]# cat /etc/yum.repos.d/jenkins.repo
[jenkins]
name=Jenkins-stable
baseurl=http://pkg.jenkins.io/redhat-stable
gpgcheck=1

Step 2: then we need to importe the key from jenkins :

[root@jenkins ~]# rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io-2023.key

Step 3: Now we can install jenkins :

[root@jenkins ~]# yum -y install jenkins

Running transaction
  Installing : jenkins-2.387.2-1.1.noarch                                                                                                                                                                     1/1
  Verifying  : jenkins-2.387.2-1.1.noarch                                                                                                                                                                     1/1
Installed:
  jenkins.noarch 0:2.387.2-1.1
Complete!

Check the the version :

[root@jenkins ~]# jenkins --version
2.387.2

Start and enable Jenkins service:

Now we need to start and enable the Jenkins service by running the following command :

[root@jenkins ~]# systemctl start jenkins
[root@jenkins ~]# systemctl enable jenkins
Created symlink from /etc/systemd/system/multi-user.target.wants/jenkins.service to /usr/lib/systemd/system/jenkins.service.

Check the status on the service :

[root@jenkins ~]# systemctl status jenkins
● jenkins.service - Jenkins Continuous Integration Server
   Loaded: loaded (/usr/lib/systemd/system/jenkins.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2023-05-02 20:58:04 +01; 34s ago
 Main PID: 22890 (java)
   CGroup: /system.slice/jenkins.service
           └─22890 /usr/bin/java -Djava.awt.headless=true -jar /usr/share/java/jenkins.war --webroot=%C/jenkins/war --httpPort=8080

Adjust the Firewall

We need to open the 8080 port so you can access to Jenkinss on your web browser :

# firewall-cmd --permanent --zone=public --add-port=8080/tcp
# firewall-cmd --reload

Configuring Jenkins

Once Jenkins is installed, you can access it on your web browser by navigating to http://<your-server-IP>:8080 :

On the login page, enter the initial admin password which can be found in the file :

/var/lib/jenkins/secrets/initialAdminPassword

Use cat commande to display your password :

[root@jenkins ~]# cat /var/lib/jenkins/secrets/initialAdminPassword

On the next screen, you will be asked whether you want to install the suggested plugins or to select specific plugins :

Choose to install suggested plugins and wait until the installation complete :

One the installation is complited, you will be asked to create the first admin user :

Fill out all required information and click on « Save and Continue ».

Click on « save and Finish ».

Finally, our automation is ready to use is ready to use :

That it,  you’ve successfully installed you automation server on your CentOS system.

To see How to reset Jenkins Admin Password click Here.