Container Tidbits: When Should I Break My Application into Multiple Containers? – Red Hat Enterprise Linux Blog

Container Tidbits: When Should I Break My Application into Multiple Containers? – Red Hat Enterprise Linux Blog:



There is a lot of confusion around which pieces of your application you should break into multiple containers and why. I recently responded to this thread on the Docker user mailing list which led me to writing today’s post. In this post I plan to examine an imaginary Java application that historically ran on a single Tomcat server and to explain why I would break it apart into separate containers. In an attempt to make things interesting – I will also aim to justify this action (i.e. breaking the application into separate containers) with data and (engineering) logic… as opposed to simply stating that “there is a principle” and that one must adhere to it all of the time.

Let’s take an example Java application made up of the following two components:

1. A front-end application built on the Struts Web Framework
2. A back-end REST API server built on Java EE

As mentioned, this application historically ran in a single Tomcat server and the two components were communicating over a REST-based API… so the question becomes:

Should I break this application into multiple containers?
Yes. I believe this application should be decomposed into two different Docker containers… but only after careful consideration.