Learn Devops: Introduction to continuous integration: Jenkins

Jenkins setup - Install Java, Jenkins, Maven, Tomcat on Ubuntu EC2 - How to install Java, Jenkins, Maven, Tomcat on Ubuntu EC2

Please follow steps to install Java, Jenkins, Maven, Tomcat on Ubuntu EC2. Jenkins is a java based application, so you need to install Java first.

Java Setup on Ubuntu

sudo apt-get update

Install Java 11

sudo apt-get install default-jdk -y

Now lets do Jenkins installation

Jenkins Setup

Add Repository key to the system

This is the Debian package repository of Jenkins to automate installation and upgrade. To use this repository, first add the key to your system:

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

Append debian package repo address to the system

Then add a Jenkins apt repository entry:

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

Update your local package index, then finally install Jenkins:

sudo apt-get update

Install Jenkins

sudo apt-get install jenkins -y

The above screenshot should confirm that Jenkins is successfully installed.

Access Jenkins in web browser

Now Go to AWS console.

Click on EC2, click on running instances link. Select the checkbox of EC2 you are installing Java and Jenkins.

Click on Action.
Copy the value from step 4 that says --> Connect to your instance using its Public DNS:

Now go to browser. enter public dns name or public IP address with port no 8080.This is how to select public DNS name:

http://EC2_public_dns_name:8080

Unlock Jenkins
You may get screen, enter the below command in Git bash( Ubuntu console)

Get the password from the below file

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

Copy the password and paste in the browser

Click on install suggested plug-ins.

Also create user name and password.

enter everything as admin. at least user name as admin password as admin

Click on Save and Finish. Click on Start to Use.

Maven
Maven is a build tool used for building Java applications. You can install Maven by executing below command:

sudo apt install maven -y

you can type mvn --version
you should see the below output.

Tomcat Installation

Tomcat is a web server or web container where java web application can be deployed by developers. DevOps best practices dictate that Tomcat be installed on a server of its own. The reason is that if your Jenkins server is down, your Tomcat server will not be down as well. In that case, you will only need to setup your Jenkins server, not Tomcat server too. This is important because as we've noted above, Tomcat is a web server that hosts our application. We do not want our application to be own for nay reason whatsoever!!!

Tomcat can be installed by executing below commands:

sudo apt-get update
sudo apt-get install tomcat8 -y

sudo apt-get install tomcat8-docs tomcat8-examples tomcat8-admin -y

sudo cp -r /usr/share/tomcat8-admin/* /var/lib/tomcat8/webapps/ -v

* Change port no from 8080 to 8090 ----> optional if you installed tomcat on a different instance
Tomcat default port is also 8080. If you have already used 8080 for Jenkins, then you need to change from 8080 to 8090. You can change by modifying server.xml

sudo vi /var/lib/tomcat8/conf/server.xml

you need to scroll down by clicking down arrow button in this file change the port no from 8080 to 8090 at line starting with <Connector port="8080" protocol="HTTP/1.1"

setup an user in tomcat

sudo vi /var/lib/tomcat8/conf/tomcat-users.xml

Scroll down all the way to the end of the file,
Add the below lines in second last line above (above </tomcat-users>)

<role rolename="manager-gui"/>
<role rolename="manager-script"/>

<user username="tomcat" password="password" roles="manager-gui,manager-script"/>

Add more memory to JVM

sudo vi /etc/default/tomcat8

Look for the line starting JAVA_OPTS and comment that line by adding #.

Add the below line:
JAVA_OPTS="-Djava.security.egd=file:/dev/./urandom -Djava.awt.headless=true -Xmx512m -XX:MaxPermSize=512m -XX:+UseConcMarkSweepGC"