Continuous integration is a term that can confuse certain people who do not constantly develop applications in a business environment. Jenkins is the software that makes it possible. So, in this tutorial, I will show you how to install Jenkins on CentOS 7.
Jenkins is an open source automation server, that provides hundreds of plugins to support building, deploying and automating any project. I’m talking about an open source application, released under the MIT license. In addition, It also requires Java for its correct execution because this is the language where it was developed.
Why Jenkins?
With Jenkins, you can automate your work-flow in large-scale application development with seamless integration.
The concept of Continuous Integration refers to a model in which a source code must be compiled and run from time to time in order to detect bugs and generate reports to improve it.
To put it another way, developers soon upload their source code to the version control repository, it is compiled, executed, and finally tested. Jenkins automates this process and makes it almost routine. However, Jenkins’ power is not limited to this.
Let’s install it on CentOS 7.
0. What you need
The purpose of this tutorial is to install Jenkins on CentOS 7. The process is not complex, but some things are required before starting:
- It is necessary to execute commands as the root user.
- The terminal is the most powerful and versatile tool Linux has. Today you will use it quite a lot, so it is recommended that you have some previous knowledge about its use.
- The team must have CentOS 7 if you use Ubuntu 18.04 this tutorial is not for you. But this one is.
1.- Upgrade the system
I always recommend updating the system, before performing any installation. Because you can get the latest security updates and thus have a more protected and reliable system.
:~$ su - :~# yum update
As I said before, doing this gives the system more secure.
2. Install Java
Jenkins requires Java to run properly, so you have to install it to continue the installation.
:~# yum install java-1.8.0-openjdk
Once the installation is complete, check the installed Java version.
:~# java -version
As you can see in the image, Java has been correctly installed.
3. Add the Jenkins Repository
Jenkins does not come by default in the CentOS 7 repositories. So we have two ways to install it. The first is to download the package in .rpm format and install it. The second is to add the repository and install it using yum. For this tutorial, I will choose the second option.
First, download the repo file.
:~# wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo
Then, import the GPG key.
:~# rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key
Finally, install Jenkins.
:~# yum install Jenkins
At the end of the download, Jenkins will be installed on the computer.
Then, enable Jenkins service to start at the system startup.
:~# systemctl enable jenkins :~# systemctl start jenkins
Next, check the Jenkins status.
:~# systemctl status jenkins
As you can see in the image, Jenkins is correctly running.
4. Setting the firewall rules
We know that CentOS 7 takes the security of the system very seriously and that is why the firewall does not allow any connection by default. For Jenkins to work, the firewall must allow connections through port 8080.
:~# firewall-cmd --zone=public --add-port=8080/tcp --permanent :~# firewall-cmd --zone=public --add-service=http --permanent :~# firewall-cmd --reload
Now, Jenkins can work well.
5. Access Jenkins web interface
Jenkins has a configuration panel with a web interface. However, before accessing the panel, it is necessary to obtain the administrator password. To do this, run the following:
#grep -A 5 password /var/log/jenkins/jenkins.log
Now, you can go to the web browser and open http://IP_SERVER:8080 and you will see this screen.
As you can see, you have to enter the password you have previously obtained.
When you set the password, you will be asked if you want to install additional plugins. I will choose to install the suggested plugins.
The installer will then complete the installation.
Next, you will need to enter information about the user to be created. Enter your username, password and email address.
When the installation is complete, you can access the Jenkins main screen.
So, that’s it.
Conclusion
Jenkins allows you to deploy and automate important tasks for application development in an enterprise environment. To install it is not complicated in a CentOS 7 system. However, it requires some previous knowledge of Linux.
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