Jenkins is a CI/CD tool.

It's an open-source automation server used to automate the repetitive tasks involved in the CI/CD of software.

Jenkins is Java based.

To install Jenkins, always follow the latest updates from the official site.

https://www.jenkins.io/doc/book/installing/linux/#debianubuntu

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Install Java

To run Jenkins, java is required.

Update your apt package index

sudo apt update

Check if Java is already installed:

java -version

If not installed then install the JRE from OpenJDK11

sudo apt install openjdk-11-jre

Install Jenkins

curl -fsSL https://pkg.jenkins.io/debian/jenkins.io-2023.key | sudo tee \
  /usr/share/keyrings/jenkins-keyring.asc > /dev/null

echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
  https://pkg.jenkins.io/debian binary/ | sudo tee \
  /etc/apt/sources.list.d/jenkins.list > /dev/null

sudo apt-get update

sudo apt-get install jenkins

Start Jenkins

Enable Jenkins service to start at boot with the command:

sudo systemctl enable jenkins

start the Jenkins service with the command:

sudo systemctl start jenkins

check the status of the Jenkins service using the command:

sudo systemctl status jenkins

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The package installation will:

• Run systemctl cat jenkins for more details.

• Create a ‘jenkins’ user to run this service.

• Direct console log output to systemd-journald. Run journalctl -u jenkins.service if you are troubleshooting Jenkins.

• Populate /lib/systemd/system/jenkins.service with configuration parameters for the launch, e.g JENKINS_HOME

• Set Jenkins to listen on port 8080. Access this port with your browser to start the configuration.

If Jenkins fails to start because a port is in use, run systemctl edit jenkins and add the following:

[Service]
Environment="JENKINS_PORT=8081"

Here, "8081" was chosen but you can put another port available.

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Post-installation setup wizard

Create an administrator user through which you can continue accessing Jenkins.

Browse to http://<ip-address>:8080 (or whichever port you configured for Jenkins when installing it) and wait until the Unlock Jenkins page appears.

Follow the instructions and set up the first Jenkins user.
Once you complete the setup, Jenkins welcome page will appear.

You installed Jenkins successfully :)