6 Using Docker volumes for persistent storage
Containers are a perfect runtime for stateless applications. You can meet increased demand by running multiple containers on your cluster, knowing that every container will handle requests in the same way. You can release updates with an automated rolling upgrade, which keeps your app online the whole time.
But not all parts of your app will be stateless. There will be components that use disks to improve performance or for permanent data storage. And you can run those components in Docker containers too.
Storage does add complications, so you need to understand how to Dockerize stateful apps. This chapter takes you through Docker volumes and mounts, and shows you how the container filesystem works. ...