Jenkins is an open-source tool a continuous integration and continuous delivery tool written in Java. Basically it will build, test and deploy your software projects.
Jenkins is primarily a build and release tool that was written by the original community as a build and release tool. They did not target it as a continuous integration continuous deployment or an orchestration tool, it was simply used for releasing builds to production. But now Jenkins has a lot of other uses like, it’s a continuous integration tool that allows developers to make sure that their environments have the exact same code as their code repositories. Let’s say there is a dev environment. If Jenkins has uses CI tool in an environment and makes sure that every comment that goes to a repository is mirrored in the environment as well. Jenkins is also used as a continuous deployment tool. Every time you do a commit it allows you to push your code to production through a series of quality gates and a lot of tests. it is also used as an orchestration tool, so people use it as a scheduler or an Orchestrator to kick off their Chef or Ansible playbooks or any other ad-hoc scripts.
In this tutorial, we will walk you through the steps of installing Jenkins on a CentOS 7 using the official Jenkins repository.
Prerequisites
To continue with this tutorial, make sure that you are logged in as a user with sudo privileges.
Installing Jenkins
You can start with the installation on your CentOS system by following the steps:
Step 1. As we mentioned above, Jenkins is a java based application, so first, we need to install Java.
sudo yum install java-1.8.0-openjdk-devel
Step 2. Next we need to enable the Jenkins repository. First we will import the GPG key:
curl --silent --location http://pkg.jenkins-ci.org/redhat-stable/jenkins.repo | sudo tee /etc/yum.repos.d/jenkins.repo
Now add the repository to your system:
sudo rpm --import https://jenkins-ci.org/redhat/jenkins-ci.org.key
Step 3. Once it is done, we will install the latest version of Jenkins with yum on your CentOS system:
sudo yum install jenkins
Once the installation is done, you can start the Jenkins service with:
sudo systemctl start jenkins
To make sure that Jenkins is started run:
sudo systemctl status jenkins
The Output should be similar to this:
● jenkins.service - LSB: Jenkins Automation Server
Loaded: loaded (/etc/rc.d/init.d/jenkins; bad; vendor preset: disabled)
Active: active (running) since Wed 2019-10-02 20:21:30 EDT; 9s ago
Docs: man:systemd-sysv-generator(8)
Process: 2606 ExecStart=/etc/rc.d/init.d/jenkins start (code=exited, status=0/SUCCESS)
Tasks: 11
Memory: 163.9M
CGroup: /system.slice/jenkins.service
└─2625 /etc/alternatives/java -Dcom.sun.akuma.Daemon=daemonized -Djava.awt.headless=true -DJENKINS_HOME=/var/lib/jenkins...
Now we are sure that Jenkins has been succesfully installed. To enable your Jenkins service to start on system boot run:
sudo systemctl enable jenkins
Setting up the Firewall
If your CentOS server is proteced by a firewall you will have to allow port 8080. To do this use the following commands:
sudo firewall-cmd --permanent --zone=public --add-port=8080/tcp
sudo firewall-cmd --reload
Accessing Jenkins
To access Jenkins, open your browser and type your domain or IP address together with the port 8080:
To print the password use the following command:
sudo cat /var/lib/jenkins/secrets/initialAdminPassword
The Output should be similar as shown below:
279fda1015ab4632a8b011ab37ae9cad
Copy this alphanumeric password and paste it into the Administrator password field and click on the Continue button.
Once you click on the Continue button you will be redirected on the customatization page:
Click on the Install suggested plugins to start the installation. Once the installation is done you will have to Create your first Admin user and put your desired Jenkins URL.
After your succesfull configuration click on the Start Using Jenkins button and you will be redirected to the Jenkins dashboard logged in as the admin user. Now you should be able to create your first Jenkins job:
In this tutorial we learned how to install and setup Jenkins on CentOS 7 machine. You can also visit the official Jenkins Documentation on how to start using Jenkins.