How to run a Jenkins in WSO2 Integration Cloud

This blog post guides you on how to run Jenkins in WSO2 Integration Cloud and configure it to build an GitHub project. Currently the WSO2 Integration Cloud does not support Jenkins as a app type, but we can use Custom docker app type with Jenkins docker image.

First we need to find out, proper Jenkins docker image, which we can use for this  or we have to build it from the scratch.

If you go to https://hub.docker.com/_/jenkins/ you can find official Jenkins images in docker hub, but we can't use this images as it is due to several reasons. So I'm going to create a fork of https://github.com/jenkinsci/docker and do some changes to the Dockerfile.

I use the https://github.com/amalkasubasinghe/docker/tree/alpine branch here.

A. You will see it has VOLUMN mount - at the moment WSO2 Integration Cloud does not allow you to upload an image which has VOLUMN mount. So we need to comment it out

#VOLUME /var/jenkins_home

B. My plan is to build Git hub project, so I need enable Git hub Integration plugin. So I add the following line at the end of the file

RUN install-plugins.sh docker-slaves github-branch-source

C. I want to build projects using Maven, so I add the following segment to the Dockerfile to install and configure Maven.

ARG MAVEN_VERSION=3.3.9

RUN mkdir -p /usr/share/maven /usr/share/maven/ref/ \

  && curl -fsSL http://apache.osuosl.org/maven/maven-3/$MAVEN_VERSION/binaries/apache-maven-$MAVEN_VERSION-bin.tar.gz \

    | tar -xzC /usr/share/maven --strip-components=1 \

  && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn

ENV MAVEN_HOME /usr/share/maven

COPY settings-docker.xml /usr/share/maven/ref/

RUN chown -R ${user} "$MAVEN_HOME"

D. I don't want to expose slave agent port 50000 to the outside. Just comment it out.

#EXPOSE 50000

E. I want to configure the Jenkins job to build the https://github.com/amalkasubasinghe/HelloWebApp/ project periodically, so I need to copy the required configurations to the Jenkins and give the correct permissions.

Note: You can first run a Jenkins on your local machine, configure the job and get the config.xml file.
I configured the Jenkins job to poll the Github project every 2 minutes and build. (You can configure the interval as you wish)

Here's the Jenkins configurations https://github.com/amalkasubasinghe/docker/blob/jenkins-alpine-hellowebapp/HelloWebApp/config.xml

<?xml version='1.0' encoding='UTF-8'?>
<project>
  <description></description>
  <keepDependencies>false</keepDependencies>
  <properties>
    <com.coravy.hudson.plugins.github.GithubProjectProperty plugin="github@1.26.1">
      <projectUrl>https://github.com/amalkasubasinghe/HelloWebApp/</projectUrl>
      <displayName></displayName>
    </com.coravy.hudson.plugins.github.GithubProjectProperty>
  </properties>
  <scm class="hudson.plugins.git.GitSCM" plugin="git@3.1.0">
    <configVersion>2</configVersion>
    <userRemoteConfigs>
      <hudson.plugins.git.UserRemoteConfig>
        <url>https://github.com/amalkasubasinghe/HelloWebApp</url>
      </hudson.plugins.git.UserRemoteConfig>
    </userRemoteConfigs>
    <branches>
      <hudson.plugins.git.BranchSpec>
        <name>*/master</name>
      </hudson.plugins.git.BranchSpec>
    </branches>
    <doGenerateSubmoduleConfigurations>false</doGenerateSubmoduleConfigurations>
    <submoduleCfg class="list"/>
    <extensions/>
  </scm>
  <canRoam>true</canRoam>
  <disabled>false</disabled>
  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
  <triggers>
    <hudson.triggers.SCMTrigger>
      <spec>H/2 * * * *</spec>
      <ignorePostCommitHooks>false</ignorePostCommitHooks>
    </hudson.triggers.SCMTrigger>
  </triggers>
  <concurrentBuild>false</concurrentBuild>
  <builders>
    <hudson.tasks.Maven>
      <targets>clean install</targets>
      <usePrivateRepository>false</usePrivateRepository>
      <settings class="jenkins.mvn.DefaultSettingsProvider"/>
      <globalSettings class="jenkins.mvn.DefaultGlobalSettingsProvider"/>
      <injectBuildVariables>false</injectBuildVariables>
    </hudson.tasks.Maven>
  </builders>
  <publishers/>
  <buildWrappers/>
</project>

We need to create the following content in the JENKINS_HOME/jobs folder, to configure a job

JENKINS_HOME
 --> jobs
         ├── HelloWebApp
         │   └── config.xml

Add the following to the Dockerfile.

RUN mkdir -p $JENKINS_HOME/jobs/HelloWebApp
COPY HelloWebApp $JENKINS_HOME/jobs/HelloWebApp

RUN chmod +x $JENKINS_HOME/jobs/HelloWebApp \
  && chown -R ${user} $JENKINS_HOME/jobs/HelloWebApp


So let's build the Jenkins image and test locally.
Go to the folder where the Dockerfile exist and execute

docker build -t jenkins-alpine .

Run the Jenkins

docker run -p 80:8080 jenkins-alpine

You will see the Jenkins logs in the command line

You can access the Jenkins via http://localhost/ and see build jobs running in every 2 minutes when it detects any changes in GitHub project.

If you click on the HelloWebApp and go to configure, then you will see the Jenkins job configurations.

So now the image is ready and let's push it to the docker hub and deploy it in WSO2 Integration Cloud.

docker images

REPOSITORY               TAG                               IMAGE ID            CREATED             SIZE
jenkins-alpine                 latest                            d7dc03cec1df        51 minutes ago      257.4 MB

docker tag d7dc03cec1df amalkasubasinghe/jenkins-alpine:hellowebapp

docker login

docker push amalkasubasinghe/jenkins-alpine:hellowebapp

When you login to the docker hub you can see the image you push

Let's login to the WSO2 Integration Cloud -> Create Application -> and select Custom Docker Image

add the image providing image URL

Wait until the security scanning finished and then create the Jenkins application selecting scanned image

Here I select Custom Docker http-8080 and https-8443 runtime, as Jenkins run in 8080 port.

Wait until the Jenkins instance fully up and running. Check the logs

Now you can access the Jenkins UI via http://esbtenant1-jenkinshellowebapp-1-0-0.wso2apps.com/

That's all :). Now every 2 minutes our Jenkins job will poll the GitHub project and if there are any changes it will pull the changes and build.

This is how you can setup and configure Jenkins in WSO2 Integration Cloud.

You can see the docker file here https://github.com/amalkasubasinghe/docker/blob/jenkins-alpine-hellowebapp/Dockerfile