This is an absolutely minimal example of a Java-based multi-docker application, under Continuous Integration by Wercker. It consists of two containers:

• a REST api service and
• a REDIS key/value store service

The REST api contains one resource which increments a page-hit counter in the REDIS service and prints a greeting containing this counter in a text/html response.

Wercker allows you to run your apps and your dependencies locally - the so called Dev Mode.

To use dev mode you need a docker environment running locally. A convenient way to get this all installed is to download the Docker Toolbox, and if you are not on Linux you need Virtualbox.

There are several ways of preparing your Docker environment to suit your specific needs. One simplistic method would be:

$ docker-machine start default

$ eval "$(docker-machine env default)"

Check your environment variables and make note of the IP assigned to your docker-machine.

$ cd <your project root = location of wercker.yml>
$ wercker dev --publish 8080

You should now be able to visit

http://<ip of your docker-machine>:8080/hello

The IP is typically 192.168.99.100. To make sure:

$ env|grep 'DOCKER_HOST'

To get started with GKE follow the instructions here

If you haven't already - create the cluster



$ gcloud container clusters create ${POD_NAME} \
            
    --num-nodes 1 \
            
    --machine-type g1-small    

Create your redis Pod with a singe instance

$ kubectl create -f kubernetes/redis-rc.json         

Then attach a service

$ kubectl create -f kubernetes/redis-svc.json

Next create the pod for the example service

$ kubectl create -f kubernetes/java-spring-redis-rc.json

And create and expose this service as a Load Balancer to the external world

$ kubectl create -f kubernetes/java-spring-redis-svc.json  

You can use Wercker to build and deploy from the command line.

$ wercker build

will build the app and

$ wercker deploy

will build the container and push it to docker hub. Finally

$ wercker deploy --deploy-target upgrade

will replace the service on GKE with a new version.

• With the current setup it is not practical to use watch/reload functionality of Wercker Dev Mode. We are looking into this. The solution is likely to be made available as a Wercker Custom Step

For further details refer to the source code as well as to the Wercker, Docker and Virtualbox documentation.