Many of the Eventuate demos require you to set the DOCKER_HOST_IP environment variable to the IP address of the Docker host.
You need to do this because some services - specifically, Apache Kafka - need to know their "public" IP address.
If you are using Docker Toolbox, this would be the IP address of the Virtual Box VM.
In other environments, such as Linux, it is the IP address (or resolvable hostname) of the machine.
See this document for more details.
The goal of this project is to diagnose a common Docker networking: whether a container can connect (e.g. an application service) to another container (e.g. Apache Kafka) using the IP address specified by DOCKER_HOST_IP.
You build a container that runs a simple NodeJS application that verifies that it can connect to itself using DOCKER_HOST_IP.
To verify that DOCKER_HOST_IP is set correctly, simply run docker-compose up
The application will display success or error information.