Docker basics, how to keep installed packages and edited files?

Question

Do I understand Docker correctly?

1. docker run -it --rm --name verdaccio -p 4873:4873 -d verdaccio/verdaccio

gets verdaccio if it does not exist yet on my server and runs it on a specific port. -d detaches it so I can leave the terminal and keep it running right?

2. docker exec -it --user root verdaccio /bin/sh

lets me ssh into the running container. However whatever apk package that I add would be lost if I rm the container then run the image again, as well as any edited file. So what's the use of this? Can I keep the changes in the image?

3. As I need to edit the config.yaml that is present in /verdaccio/conf/config.yaml (in the container), my only option to keep this changes is to detach the data from the running instance? Is there another way?

    V_PATH=/path/on/my/server/verdaccio; docker run -it --rm --name verdaccio -p 4873:4873 \\ -v $V_PATH/conf:/verdaccio/conf \\ -v $V_PATH/storage:/verdaccio/storage \\ -v $V_PATH/plugins:/verdaccio/plugins \\ verdaccio/verdaccio 

However this command would throw

fatal--- cannot open config file /verdaccio/conf/config.yaml: ENOENT: no such file or directory, open '/verdaccio/conf/config.yaml'

Answer 1

You can use docker commit to build a new image based on the container.

A better approach however is to use a Dockerfile that builds an image based on verdaccio/verdaccio with the necessary changes in it. This makes the process easily repeatable (for example if a new version of the base image comes out).

A further option is the use of volumes as you already mentioned.