DevopsPilot

How to create a Freestyle project in Jenkins to build a Maven Java project

Install Maven in the Jenkins server

sudo apt install maven
ubuntu@jenkins-test:~$ sudo apt install maven
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
  libaopalliance-java libapache-pom-java libatinject-jsr330-api-java libcdi-api-java libcommons-cli-java libcommons-io-java
  libcommons-lang3-java libcommons-parent-java liberror-prone-java libgeronimo-annotation-1.3-spec-java
  libgeronimo-interceptor-3.0-spec-java libguava-java libguice-java libjansi-java libjsr305-java libmaven-parent-java
  libmaven-resolver-java libmaven-shared-utils-java libmaven3-core-java libplexus-cipher-java libplexus-classworlds-java
  libplexus-component-annotations-java libplexus-interpolation-java libplexus-sec-dispatcher-java libplexus-utils2-java
  libsisu-inject-java libsisu-plexus-java libslf4j-java libwagon-file-java libwagon-http-shaded-java libwagon-provider-api-java
Suggested packages:
  libatinject-jsr330-api-java-doc libel-api-java libcommons-io-java-doc libasm-java libcglib-java libjsr305-java-doc
  libmaven-shared-utils-java-doc liblogback-java libplexus-utils2-java-doc junit4 testng libcommons-logging-java liblog4j1.2-java
The following NEW packages will be installed:
  libaopalliance-java libapache-pom-java libatinject-jsr330-api-java libcdi-api-java libcommons-cli-java libcommons-io-java
  libcommons-lang3-java libcommons-parent-java liberror-prone-java libgeronimo-annotation-1.3-spec-java
  libgeronimo-interceptor-3.0-spec-java libguava-java libguice-java libjansi-java libjsr305-java libmaven-parent-java
  libmaven-resolver-java libmaven-shared-utils-java libmaven3-core-java libplexus-cipher-java libplexus-classworlds-java
  libplexus-component-annotations-java libplexus-interpolation-java libplexus-sec-dispatcher-java libplexus-utils2-java
  libsisu-inject-java libsisu-plexus-java libslf4j-java libwagon-file-java libwagon-http-shaded-java libwagon-provider-api-java maven
0 upgraded, 32 newly installed, 0 to remove and 0 not upgraded.

Check maven version

mvn --version
ubuntu@jenkins-test:~$ mvn --version
Apache Maven 3.8.7
Maven home: /usr/share/maven
Java version: 21.0.3, vendor: Ubuntu, runtime: /usr/lib/jvm/java-21-openjdk-amd64
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "6.8.0-1009-azure", arch: "amd64", family: "unix"

Installed Maven version is 3.8.7

NOTE: To install Maven, Java should be installed first

Create Freestyle Project

Goto Jenkins dashboard, click on New Item

Enter the Freestyle project name freestyle-project-maven, select Freestyle project and then click OK

Select Source Code Management -> Git Enter your Public GitHub repository https URL where you have the Maven Java Project

If you don’t have a sample Hello World Maven Java project. Fork this Github repository https://github.com/vigneshsweekaran/hello-world and use your Github repository URL

Enter Branch Specifier as main

Click on Build Steps -> Add build steps -> Execute shell

Enter mvn clean package command and click on Save

Build the Freestyle Project

Click on Build Now to run a Freestyle project

1st Build started

Click on Build Number #1 to see the details

Here you can see,

  • Who triggered this Freestyle project
  • GitHub repository URL
  • Github repository Branch
  • Commit id

Now click on Console output to see the Build logs

Click on Full Log

Here you can see Jenkins is building this Freestyle project in the Jenkins server from /var/lib/jenkins/workspace/freestyle-project-maven folder

  • Jenkins HOME folder is /var/lib/jenkins, under this folder, Jenkins keeps all the details as files
  • In /var/lib/jenkins/workspace it keeps track of any Freestyle projects or Pipelines created in Jenkins
  • In this case, the Freestyle Project name is freestyle-project-maven so it created a freestyle-project-maven folder in /var/lib/jenkins/workspace E.g. /var/lib/jenkins/workspace/freestyle-project-maven

Jenkins will clone the GitHub repository given during the Freestyle project creation in this folder for building

You can verify the same in the Jenkins server

Change to root user in Jenkins server

sudo su
ubuntu@jenkins-test:~$ sudo su
[sudo] password for ubuntu: 
root@jenkins-test:/home/ubuntu#

Goto /var/lib/jenkins/workspace/freestyle-project-maven and list the files there

cd /var/lib/jenkins/workspace/freestyle-project-maven
pwd
ls -l
root@jenkins-test:/home/ubuntu# cd /var/lib/jenkins/workspace/freestyle-project-maven/
root@jenkins-test:/var/lib/jenkins/workspace/freestyle-project-maven# pwd
/var/lib/jenkins/workspace/freestyle-project-maven
root@jenkins-test:/var/lib/jenkins/workspace/freestyle-project-maven# ls -l
total 44
-rw-r--r--  1 jenkins jenkins   95 Jul  7 13:01 Dockerfile
-rw-r--r--  1 jenkins jenkins 2654 Jul  7 13:16 README.md
-rw-r--r--  1 jenkins jenkins  646 Jul  7 13:01 appspec.yml
-rw-r--r--  1 jenkins jenkins 2146 Jul  7 13:01 buildspec.yml
drwxr-xr-x  3 jenkins jenkins 4096 Jul  7 13:16 cicd
drwxr-xr-x  3 jenkins jenkins 4096 Jul  7 13:01 codedeploy
drwxr-xr-x  5 jenkins jenkins 4096 Jul  7 13:01 deployment
-rw-r--r--  1 jenkins jenkins 1414 Jul  7 13:16 pom.xml
-rw-r--r--  1 jenkins jenkins  231 Jul  7 13:01 sonar-project.properties
drwxr-xr-x  4 jenkins jenkins 4096 Jul  7 13:01 src
drwxr-xr-x 10 jenkins jenkins 4096 Jul  7 13:42 target

And in the Console Output you can see No credentials specified is mentioned. While creating the Freestyle Project, you have given the Public Github repository URL and you have not selected any github credentials.

Next its cloning the repository with latest Git Commit Id from the branch refs/remotes/origin/main

Next its executing the command mvn clean package which you have given in the Build Steps -> Execute Shell

Once the build is completed, it creates a war file in the path /var/lib/jenkins/workspace/freestyle-project-maven/target/hello-world-1.0-SNAPSHOT.war