Jenkins is a powerful, free automation tool used in the software development life cycle. It is a Java-based tool that allows you to build, test and deploy code automatically. Jenkins offers many plugins built for Continuous Integration purposes. It allows developers to integrate changes to the project and send a fresh build to users. Jenkins is cross-platform so it can be installed on all major operating systems. It has more than 147,000 active installations and over 1 million users around the world.

In this post, we will show you how to install Jenkins on Oracle Linux 8.

Step 1 – Install Java

Jenkins is a Java-based tool, so Java must be installed on your server. If not installed you can install it using the following command:

dnf install java-11-openjdk -y

Once the Java is installed, verify the Java version using the following command:

java --version

Sample output:

openjdk 11.0.15 2022-04-19 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.15+10-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.15+10-LTS, mixed mode, sharing)

Step 2 – Add Jenkins Repository

By default, Jenkins is not included in the OracleLinux 8 default repository so you will need to create a Jenkins repo on your system. You can create it using the following command:

wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo

Next, download and import the Jenkins GPG key with the following command:

rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key

Next, verify the Jenkins repo using the following command:

dnf repolist

Sample output:

repo id                                                         repo name
appstream                                                       Oracle Linux 8 - AppStream
baseos                                                          Oracle Linux 8 - BaseOS
extras                                                          Oracle Linux 8 - Extras
jenkins                                                         Jenkins-stable

Step 3 – Install Jenkins

Now you can install Jenkins using the following command:

dnf install jenkins --nobest

Once Jenkins is installed, start Jenkins and enable it to start at system reboot:

systemctl start jenkins
systemctl enable jenkins

You can now check the status of Jenkins using the following command:

systemctl status jenkins

Sample output:

● jenkins.service - Jenkins Continuous Integration Server
   Loaded: loaded (/usr/lib/systemd/system/jenkins.service; disabled; vendor preset: disabled)
   Active: active (running) since Sun 2022-05-29 13:23:56 EDT; 8s ago
 Main PID: 13177 (java)
    Tasks: 50 (limit: 23694)
   Memory: 1.1G
   CGroup: /system.slice/jenkins.service
           └─13177 /usr/bin/java -Djava.awt.headless=true -jar /usr/share/java/jenkins.war --webroot=/var/cache/jenkins/war --httpPort=8080

May 29 13:23:38 oraclelinux8 jenkins[13177]: Please use the following password to proceed to installation:
May 29 13:23:38 oraclelinux8 jenkins[13177]: 000a6fdc7f9d4d05b39029d776f34fd6
May 29 13:23:38 oraclelinux8 jenkins[13177]: This may also be found at: /var/lib/jenkins/secrets/initialAdminPassword
May 29 13:23:38 oraclelinux8 jenkins[13177]: *************************************************************
May 29 13:23:56 oraclelinux8 jenkins[13177]: 2022-05-29 17:23:56.786+0000 [id=45]        INFO        h.m.DownloadService$Downloadable#load: O>
May 29 13:23:56 oraclelinux8 jenkins[13177]: 2022-05-29 17:23:56.787+0000 [id=45]        INFO        hudson.util.Retrier#start: Performed the>
May 29 13:23:56 oraclelinux8 jenkins[13177]: 2022-05-29 17:23:56.790+0000 [id=45]        INFO        hudson.model.AsyncPeriodicWork#lambda$do>
May 29 13:23:56 oraclelinux8 jenkins[13177]: 2022-05-29 17:23:56.963+0000 [id=29]        INFO        jenkins.InitReactorRunner$1#onAttained: >
May 29 13:23:57 oraclelinux8 jenkins[13177]: 2022-05-29 17:23:56.993+0000 [id=22]        INFO        hudson.lifecycle.Lifecycle#onReady: Jenk>
May 29 13:23:56 oraclelinux8 systemd[1]: Started Jenkins Continuous Integration Server.

By default, Jenkins listens on port 8080. You can verify it with the following command:

ss -antpl | grep 8080

Sample output:

LISTEN 0      50                 *:8080            *:*    users:(("java",pid=13177,fd=117))

Step 4 – Configure Nginx as a Reverse Proxy for Jenkins

It is a good idea to install and configure Nginx as a reverse proxy for Jenkins. First, install the Nginx web server with the following command:

dnf install nginx -y

After installing Nginx, create an Nginx configuration file for Jenkins:

nano /etc/nginx/conf.d/jenkins.conf

Add the following lines:

upstream jenkins {
  server 127.0.0.1:8080 fail_timeout=0;
}

server {
  listen 80;
  server_name jenkins.example.com;

  location / {
    proxy_set_header        Host $host:$server_port;
    proxy_set_header        X-Real-IP $remote_addr;
    proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header        X-Forwarded-Proto $scheme;
    proxy_pass              http://jenkins;
    # Required for new HTTP-based CLI
    proxy_http_version 1.1;
    proxy_request_buffering off;
    proxy_buffering off; # Required for HTTP-based CLI to work over SSL
  }
}

Save and close the file when you are finished. Then, edit the Nginx main configuration file:

nano /etc/nginx/nginx.conf

Define the hash bucket size as shown below:

http {

server_names_hash_bucket_size 64;

Next, verify Nginx for any syntax errors:

nginx -t

Sample output:

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

Finally, start the Nginx service and enable it to start at system reboot:

systemctl start nginx
systemctl enable nginx

Step 5 – Access Jenkins Dashboard

Now, you can access the Jenkins web interface using the URL http://jenkins.example.com from the web browser. You should see the following screen:
Jenkins LoginNow, open your terminal and retrieve the Jenkins setup password using the following command:

cat /var/lib/jenkins/secrets/initialAdminPassword

Sample output:

000a6fdc7f9d4d05b39029d776f34fd6

Now, paste the above password and click on the Continue button. You should see the following screen:
Jenkins Plugins Installation
Now, select ‘Install using suggested plugins‘ or ‘Select plugins to install‘. You should see the following screen:
Jenkins Admin User Creation
Now, provide your admin user information and click on the Save and Continue button. You should see the following screen:
Jenkins Define URL
Now, provide your Jenkins URL and click on the Save and Finish button. You should see the following screen:
Jenkins Installed
Click on the Start Using Jenkins. You should see the Jenkins Dashboard on the following screen:
Jenkins Dashboard

Conclusion

In this post, we explained how to install Jenkins on OracleLinux 8 with Nginx as a reverse proxy. You can now use Jenkins in your software development environment and automate the development process with ease. Give it a try on your dedicated server from Atlantic.Net!