isabella232 / tomcat_cluster

Tomcat Clusters in Docker

This repository demonstrates deploying tomcat clusters for stateful applications. The first application demonstrates configuring Nginx as a load balancer that maintains the same session id regardless of which server receives the request. The second application demonstrates using HAProxy to keep a session to a specific server.

Running the demos

Build the application container

The demonstration uses a tomcat container configured to use clustering and a Java Server Pages app that shows the sessionid an containerid. To build the tomcat container

cd ./tomcat
docker image build -t tomcat-cluster .

Stateful demo

To run the demo:

docker-compose up -d

Go to http://localhost:8080/cluster in your browser. Refresh the browser repeatedly and you can see that the instance changes but the session in the browser remains the same.

Sticky session demo

To run the demo:

docker stack deploy -c docker-stack.yml cluster

Go to http://localhost/cluster in your browser. Refresh the browser several time and the container instance and sessionid remain the same. Open a different browser and it will create a new session id on a different instance.