I'm looking to see if it is possible to somehow FTP into an already existing Docker container? For example, I'm using the [dockerfile/ghost](https://github.com/dockerfile/ghost) in combination with [jwilder/nginx-proxy](https://github.com/jwilder/nginx-proxy), and once I deploy/build a container, I'd like for the user to be able to FTP into the container running Ghost so they can upload additional files such as themes, stylesheets, etc. What would be the best method in accomplishing this? Thanks in advance!