DevOps : Jenkins Installation and Setup

What is Jenkins ? 

Jenkins is a software that allows continuous integration. Jenkins will be installed on a server where the central build will take place.

What is continuous integration  ?

Continuous Integration is a development practice that requires developers to integrate code into a shared repository at regular intervals. This concept was meant to remove the problem of finding later occurrence of issues in the build lifecycle. 

Continuous integration requires the developers to have frequent builds. The common practice is that whenever a code commit occurs, a build should be triggered.

Below steps will explain how to install and configure Jenkins with Git plugin. 

Prerequisite:

Step 1: Download the JDK from Oracle

https://www.oracle.com/technetwork/java/javase/downloads/index.html

Download 32 bit it 64 based on your OS platform.

Step 2: Install Java on Windows

Create a directory and install the java under that. ( Here I showed as _jdk10 under c: )

Step 3: Set up JAVA_HOME on Windows

Step 4: Configure the Java path setting

Step 5: Verify the JDK installation

After the JDK is installed on Windows, the JAVA_HOME setup is complete, and you've configured the Java path setting.

The last thing you need to do is verify the Java 10  / 11 installation actually works. To do so, simply open up a command prompt, and enter the following command:

>java.exe –version

If you followed these steps, you have successfully installed the JDK and configured the JAVA_HOME variable and the Java path setting on Windows.

STEP 6: Download  Jenkins WAR file

To begin this step by step Jenkins tutorial, you must first download the product binaries.

https://jenkins.io/download/

The best way for beginners to learn Jenkins is to choose the Generic Java package (.war) option. This option downloads a single file named jenkins.war, which is run on the command line.

Step 7: Download Tomcat

Browse to the link https://tomcat.apache.org/download-90.cgi to get the download for tomcat.

Step 8: Jenkins and Tomcat Setup

Copy the Jenkis.war file which was downloaded from the previous section and copy it to the webapps folder in the tomcat folder.

Now open the command prompt. From the command prompt, browse to the directory where the tomcat9 folder located. Browse to the bin directory in this folder and run the start.bat file

>C:\Apps\apache-tomcat-9.0.14\bin>startup.bat

Once the processing is complete without major errors, the following line will come in the output of the command prompt.

INFO: Server startup in 1302 ms

Open the browser and go to the link − http://localhost:8080/jenkins. Jenkins will be up and running on tomcat.

Step 9 : SETUP GIT 

In your Jenkins Dashboard (Home screen), click the Manage Jenkins option on the left hand side.

In the next screen, click the Available tab. This tab will give a list of plugins which are available for downloading. In the ‘Filter’ tab type ‘Git plugin’

The list will then be filtered. Check the Git Plugin option and click on the button ‘Install without restart’. 

Step 10 : Restart Jenkins 

Once all installations are complete, restart Jenkins by issue the following command in the browser. http://localhost:8080/jenkins/restart

After Jenkins is restarted, Git will be available as an option whilst configuring jobs. To verify, click on New Item in the menu options for Jenkins.

Then enter a name for a job, in the following case, the name entered is ‘Demo’.

Select ‘Freestyle project’ as the item type. Click the Ok button.

In the next screen, if you browse to the Source code Management section, you will now see ‘Git’ as an option.

Now we have successfully configured Jenkins with Git.