JENKINS: a continuous integration tool

Getting started with Jenkins is 3 step process:

- Install Jenkins
- Download the required plugins
- Configure the plugins & create a project

# Installing Jenkins in Ubuntu
$ wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key  | sudo apt-key add -
$ sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ \
  > /etc/apt/sources.list.d/jenkins.list'
$ sudo apt-get update
$ sudo apt-get install jenkins
  //this will automatically start Jenkins

# Installing Jenkins in AWS-EC2
$ sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat/jenkins.repo
$ sudo rpm --import https://pkg.jenkins.io/redhat/jenkins.io.key
$ sudo yum install -y jenkins
$ sudo yum install java -y
$ sudo service jenkins start
$ chkconfig jenkins on

# If your /etc/init.d/jenkins file fails to start jenkins then,
edit the /etc/default/jenkins to replace the HTTP_PORT=8080 to HTTP_PORT=8081
or
$ cd /var/share/jenkins/
$ java -jar jenkins.war // this will setup a new jenkins from begining

# I prefer to use below, this will start old jenkins without any delay
$ service jenkins restart

# Running docker container of Jenkins
$ docker pull punitporwal07/jenkins
$ docker run -d -p 8081:8080 -v jenkins-data:/software/jenkins punitporwal07/jenkins:tag
  to understand this command in brief check here: Docker

# Depending on configs to system, jenkins file structure may vary -
  /etc/sysconfig/jenkins
  /var/lib/jenkins/
  /etc/default/jenkins

Useful Plugins

you can push from manage plugins tab/ push from back-end into plugins dir

- Build pipeline: to chain multiple jobs
- Delivery pipeline: this will visualize deliver pipelines (upstream/downstream)
- Weblogic deployer: this is used to deploy a jar/war/ear to any weblogic target
- Deploy to container: to deploy war/ear to a tomcat/glassfish container
- Roles strategy: this plugin allows you to assign roles to the different user of jenkins

Automate deployment on Tomcat using Jenkins pipeline

(benefits.war as an example on tomcat 8.x for Linux)

- install Deploy to container plugin, restart Jenkins to reflect changes
- create a new project/workspace & select post-build action as- Deploy war/ear to a container
- add properties as below:-
   - war/ear files: **/*.war
   - context path: benefits.war (provided you need to push this war file into your workspace)
   - select container from the drop-down list: tomcat 8.x
   - Add credentials: tomcat/tomcat (provided you have added this user in conf/tomcat-user.xml with all the required roles)
   - Tomcat URL: http://localhost:8080/
- apply/save your project and build it to validate the result.

Automate deployment on Weblogic using Jenkins pipeline

(benefits.war as an example on Weblogic 10.3.6)

- install Weblogic deployer plugin, restart jenkins to reflect changes
- configure the plugin,
- create new project/workspace
- Add post-build action as- Deploy the artefact to any weblogic environment (if no configuration has been set, the plugin will display an error message, else it will open up a new window)
- add properties as below:-
   - Task Name: give any task name
   - Environment: from the drop-down list select your AdminServer ( provided you have created configuration.xml and added it to Weblogic deployer Plugin)
   - Name: The name used by the WebLogic server to display the deployed component
   - Base directory of deployment: give the path to your deployment.war or push it to your workspace and leave it blank
   - Built resource to deploy: give your deployment.war name
   - Targets: give target name
- Apply/save your project and build it to validate the result.

Possible failure of your Jenkins jobs
Problem - Jenkins: java.lang.OutOfMemoryError: Java heap space

Solution - Navigate to your Jenkins project, click configure.

Scroll down to the Build section of the page to the Build Step with your plugin title:

Click Advanced…

In the System/Java Options field, add the following parameter

JAVA_ARGS="-Xmx2048m -XX:MaxPermSize=512m"

This will assign 2Gi of memory to you build.

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