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KumuluzEE Feature Flags sample with Unleash

The objective of this sample is to show how to use feature flags in KumuluzEE. You will add KumuluzEE dependencies into pom.xml. You will create configuration and check if the flags are enabled using Unleash client.


In order to run this example you will need the following:

  1. Java 8 (or newer), you can use any implementation:

    • If you have installed Java, you can check the version by typing the following in a command line:

      java -version
  2. Maven 3.2.1 (or newer):

    • If you have installed Maven, you can check the version by typing the following in a command line:

      mvn -version
  3. Git:

    • If you have installed Git, you can check the version by typing the following in a command line:

      git --version
  4. Unleash:

    • run Unleash with docker, you can find a guide here


The example uses maven to build and run the microservices.

  1. Build the sample using maven:

    $ cd kumuluzee-feature-flags-unleash
    $ mvn clean package
  2. Run the sample:

  • Uber-jar:

    $ java -jar target/${}.jar

    in Windows environemnt use the command

    java -jar target/${}.jar
  • Exploded:

    $ java -cp target/classes:target/dependency/*

    in Windows environment use the command

    java -cp target/classes;target/dependency/*

The application/service can be accessed on the following URL:

To shut down the example simply stop the processes in the foreground.


This tutorial will guide you through the steps required to connect to a feature flag server and use it's flags. We will extend the existing KumuluzEE JAX-RS REST sample to test if the flags are enabled or disabled. Therefore, first complete the existing JAX-RS sample tutorial, or clone the JAX-RS sample code.

We will follow these steps:

  • Complete the tutorial for KumuluzEE JAX-RS REST sample or clone the existing sample
  • Ensure access to Unleash server
  • Add Maven dependencies
  • Build the microservice
  • Run it

Add Maven dependencies

Since your existing starting point is the existing KumuluzEE JAX-RS REST sample, you should already have the dependencies for kumuluzee-bom, kumuluzee-core, kumuluzee-servlet-jetty and kumuluzee-jax-rs-jersey configured in the pom.xml.

Add the feature-flags-unleash dependency:


Add the kumuluzee-maven-plugin build plugin to package microservice as uber-jar:


or exploded:


Configure Unleash connection

In the directory resources edit the file config.yaml by adding the following RabbitMQ properties:

  name: feature-flags-sample-service
  version: 1.0.0
    name: dev
      unleash-api: "http://localhost:4242/api"

Optionally, you can create UnleashConfig object in a class annotated with @FFConnection

public class UnleashConnection {  
    UnleashConfig config = UnleashConfig  

Creating a flag

Access the admin UI on http://localhost:4242 and create a new flag. Name it "test-feature" (or whatever you want, but don't forget to correct the flag name in the code after).

Using feature flags

You can check if feature flags are enabled by using FeatureFlags object in the same way as you would use Unleash client object.

private FeatureFlags featureFlags;

    //do something
} else {
    //do something else

Build the microservice and run it

To build the microservice and run the example, use the commands as described in previous sections.

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