edwin Posts

Creating a Jenkins Slave Image with Maven 3.6, Java 11 and Skopeo

Openshift have a default maven Jenkins slave image, but too bad it is build on top of Java 8. And on this project which im currently working on, i need a custom Jenkins slave but with Java 11 and the ability to move images between Image Registry. Therefore i create a custom Dockerfile which contains Skopeo, Maven 3.6.3 and Java 11. Below is the detail Dockerfile which i created,

FROM openshift/jenkins-slave-base-centos7:v3.11

MAINTAINER Muhammad Edwin < edwin at redhat dot com >


# install skopeo
RUN yum install skopeo -y && yum clean all

# install java
RUN curl -L --output /tmp/jdk.tar.gz https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_linux-x64_bin.tar.gz && \
	tar zxf /tmp/jdk.tar.gz -C /usr/lib/jvm && \
	rm /tmp/jdk.tar.gz && \
	update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-11.0.2/bin/java 20000 --family java-1.11-openjdk.x86_64 && \
	update-alternatives --set java /usr/lib/jvm/jdk-11.0.2/bin/java
# Install Maven
RUN curl -L --output /tmp/apache-maven-bin.zip  https://www-eu.apache.org/dist/maven/maven-3/${MAVEN_VERSION}/binaries/apache-maven-${MAVEN_VERSION}-bin.zip && \
    unzip -q /tmp/apache-maven-bin.zip -d /opt && \
    ln -s /opt/apache-maven-${MAVEN_VERSION} /opt/maven && \
    rm /tmp/apache-maven-bin.zip && \
    mkdir -p $HOME/.m2

RUN chown -R 1001:0 $HOME && chmod -R g+rw $HOME

COPY run-jnlp-client /usr/local/bin/

USER 1001

Build by using this command,

docker build -t jenkins-slave-skopeo-jdk11-new -f skopeo-jdk11.dockerfile .

Pull the image to Openshift,

oc import-image docker.io/edwinkun/jenkins-slave-skopeo-jdk11-new --confirm

Register on Jenkins as a

And try on

node('maven') {
	stage('Clone') {
		sh "git config --global http.sslVerify false"
		sh "git clone https://github.com/edwin/hello-world.git"
	stage('Build') {
		sh "mvn -v"
		sh "mvn clean package -f hello-world/pom.xml"

This is the result,

Detail code can be seen on my github page, https://github.com/edwin/jenkins-slave-maven-jdk11-skopeo


Connecting From Jenkins to Git Repository such as Gitlab, without Plugins

Basically all you need is your repository url, username and password.

First is adding your git username and password on Jenkins credentials,

And after that, we can create a username and password credentials, and we give an id with the name of “devops”.

Use this jenkins script to execute git commands,

node('maven') {
	stage('Clone') {
		sh "git config --global http.sslVerify false"
		git branch:"branch-01", url:"https://git.mygit.id/git/something/project.git", credentialsId:'devops'

Reading Original IP on Keycloak when Installed Behind a Reverse Proxy

Keycloak, or Red Hat Single SignOn, have the capability of capturing ip of every request which are connected to it. But there are scenarios where Keycloak is located behind a reverse proxy, and Keycloak would capture reverse proxy’s ip instead of original requestor IP.

The workaround is actually quite simple although can be at different xml files depends on your server , can add below configuration on default-server tag.

<server name="default-server">
	<http-listener name="default" socket-binding="http" redirect-socket="https" enable-http2="true"
		proxy-address-forwarding="true" />
	<https-listener name="https" socket-binding="https" security-realm="ApplicationRealm" enable-http2="true"
		proxy-address-forwarding="true" />
	<host name="default-host" alias="localhost">
		<location name="/" handler="welcome-content"/>
		<http-invoker security-realm="ApplicationRealm"/>

Starting JBoss EAP or Wildfly with a Specific XML Configuration

We can run EAP or Wildfly with a specific XML configuration, not just the default one. For example we have a new configuration with the name of standalone-full-ha_1.xml, and want to run EAP based on it. First we need to put corresponding XML on below directory,


And run using below command,

standalone.bat -c standalone-full-ha_1.xml



Monitoring Kafka Topics with Dockerized Kafka Manager

Yesterday, Dimas (one of my colleague), are asking me on how to monitor Kafka which are running on top of Openshift using a tools which are accessible thru browser.

One of the tools im recommending is Kafka Manager, which we can download from below url,


Lets start from the beginning, from how to start Zookeeper, Kafka Server, until simulate a simple produce and consume and monitoring it using Kafka Manager.

First, download Kafka from Apache site, extract it, and open bin folder. We need Zookeeper to start before we start anything else. Fyi for this example im using Win10 as my primary Operating System, so all my command below can be different depends on what Operating System you are using.

cd D:\software\kafka_2.13-2.4.0\bin\windows
zookeeper-server-start.bat ..\..\config\zookeeper.properties

And run Kafka Server afterwards,

kafka-server-start.bat ..\..\config\server.properties

Create a topic,

kafka-topics.bat --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic my-testing-topic

Try produce a simple echo message using Kafka Producer,

kafka-console-producer.bat --broker-list localhost:9092 --topic my-testing-topic

And listen to the sent message using Kafka Consumer,

kafka-console-consumer.bat --bootstrap-server localhost:9092 -topic  my-testing-topic --from-beginning

If you only want to get all the new message, ignoring the old one, just remove “–from-beginning” parameter. And use “–offset” parameter to get a specific offset.

Next is running my Kafka Manager using Docker command. Fyi, is my laptop ip.

docker run --network host --add-host=moby: --add-host DESKTOP: -p 9000:9000 -e ZK_HOSTS=""  kafkamanager/kafka-manager

After Kafka-Manager is successfully started, we can browse our Kafka by opening thru browser,