Running a Server Container

We just saw how to run short-lived containers. They usually do some processing and display some output. However, there’s a very common use for long-lived containers: server containers. Whether you want to host a web application, an API, or a database, you want a container that listens for incoming network connections and is potentially long-lived.

A word of warning: it’s best not to think about containers as long-lived, even when they are. Don’t store information inside the containers. In other words, ensure your containers are stateless, not stateful. A stateless container never stores its state when it is run while stateful containers store some information about their state each time they are run. We’ll see later on how and where to store your container’s state. Docker containers are very stable, but the reason for having stateless containers is that this allows for easy scaling up and recovery. More about that later.

In short, a server container

• is long-lived
• listens for incoming network connections

How can we manage this? Read on.