Deploying with JRuby 9k

Creating a Docker Image

A Docker image is defined by a Dockerfile, which is a text document containing instructions Docker follows as it provisions a new container. To create a Docker image for your WAR file, you must create a Dockerfile in the project.

To begin, move into the root directory of the stock-service application you implemented in Chapter 1, ​Getting Started with JRuby​.

$ cd ~/code/stock-service

Then create a Dockerfile in that directory and put the following code in it:

Warbler/stock-service-docker/Dockerfile

FROM heroku/jvm

ADD ./stock-service.war /app/user/

This defines an image that inherits from the heroku/jvm image. It then tells Docker to add the WAR file from the local machine to the /app/user directory ...