A common example of comparing single-container and multi-container Pods is a web server that utilizes a file synchronizer.

The example

In this example there are two clear concerns:

1. Serving the web page
2. Making sure the content is up to date

The question is whether to address the two concerns in a single container or two separate containers.

In this context, a concern is a requirement or a task. Generally speaking, microservices design patterns dictate that we separate concerns. This means we only ever deal with one concern per container.

Assuming the previous example, this will require two containers: one for the web service, another for the file sync service.

This model of separating concerns has a lot of advantages, including:

• Different teams can be responsible for each of the two containers.
• Each container can be scaled independently.
• Each container can be developed and iterated independently.
• Each container can have its own release cadence.
• If one fails, the other keeps running.