Alberto Salazar

Java Champion - Oracle Groundbreaker Ambassador - Jug Leader - Auth0 Ambassador & JCP Associate Member.

True believer in open source, passionate developer. Founder,,


Events and Conferences..

18 June 2017

Apache Karaf to Microservices Architecture!

by Alberto Salazar


This is the demo project for the ‘Microservices and OSGi’; the project on Github you can download or clone from:

This sample project it a fork of the repository:

It consists of following sub-modules:


First of all make sure you also have the Karaf-Microservices-Tooling project build. The service-test module does use a specialized pre-configured Karaf instance, Karaf-Service-Runtime.


All of the Microservice samples are can be build with maven.

mvn clean install

while for Dev-Ops development with continous deployment a special deployment goal exists.


With this maven goal you can deploy any module on a Karaf instance (if it’s a OSGi bundle) These samples already does have a the usage of this goal preconfigured.

"arguments":["mvn:${project.groupId}/${project.artifactId}/${project.version}", true]

For easy testing the pre-configured Karaf instance can also be run as Docker image right away from the project. For this call


to start the docker instance and


to stop that instance again.


This is a short walkthrough of this sample.

First make sure you have docker installed and running. Clone the Karaf-Microservices-Tooling from the github repo and do a full build of it. In the Karaf-Docker-Runtime submodule start the Karaf-Docker instance with

mvn docker:start

after this docker container is started it can be used as continuous deployment container for the showcase. The showcase can be build with mvn clean install. To deploy the showcase bundle to the Karaf-Docker instance use:

mvn karaf-deployer:deploy

This will deploy the current bundle in the configured Karaf instance. In case of deploying to the Karaf-Docker instance make sure the ip address is properly configured in the karaf-deployer-maven-plugin section.

complete showcase

For easy testing there is an additional service-configuration bundle, which is enabled by enabling the Configuration profile. The complete showcase including the configuration can be build with

mvn clean install karaf-deployer:deploy -PConfiguration

when ssh’ing into the Karaf instance

ssh karaf@ -p 8101

you’ll see all bundles are installed and usable. For example the commands contained in the service-shell-command bundle can be used to test the service.

karaf@root()> microservice:Calculate

proxy REST servlet

The proxy REST servlet is a specialized JAX-RS servlet to proxy calls to any service instance of the CreditCalculator type. Those services are configured via de.nierbeck.microservices.karaf.calculator Service Factory PID. To get a list of all available service instances a GET request to

lists all available services of type CreditCalculator.

With a GET call to:

a sample Calculator JSON object is returned. This JSON can be used for the calculation.

To calculate with a dedicated service instance a POST request to the following URL is required.

For a successful call make sure you have Content-Type set to application/json in the request header. The body to send via POST can be retrieved via the find call.

    "credit": {
        "credit": 10000,
        "interest": 2.5,
        "retention": 10
tags: Microservices

About me.

Java Professional with more than 17 years experience creating Java architectures for large scalable, high transaction load systems since J2EE 1.3 and receltly honored as Java Champion, Oracle Groundbreaker Ambassador and Auth0 Ambassador .

Java Champion, JugLeader, Oracle Groundbreaker Ambassador, Auth0Ambassador & JCPMember.Founder Java Users Group Ecuador and Javaday Ecuador Conference. Speaker at world class conferences such as: JavaOne, Oracle Code, Redhat Summit, Oracle Code Latam Tour, Oracle OTN LAD and locally ECUADOR Java Users Group.

I also start evangelize Java between 2006 to 2010 like an official trainner of SUN Microsystems, Inc. Of the certification java path like: SL-285 Developing Applications With the Java SE Platform, FJ-310 Developing Applications for the Java EE Platform, SL-314 Web Component Development with Servlet and JSP Technologies.

Certified as: Oracle Certified Master Java EE5 Enterprise Architect Step1. Sun Certified Programmer for the Java Platform Standard Edition 5. Sun Certified Professional. SOA Certified Profesional, Apache Service Mix & Apache Camel Advanced Developer Advaced Integration and more....