Many ways to do the same thing

General
1

Why are there many ways to do the same thing between docker build and run?

docker build --volume /tmp -t tag . is the same exact thing as adding VOLUME in the Dockerfile. But regardless, these methods aren’t actually doing anything but creating a directory because you still need to bind the volume when you do docker run --volume /tmp:/tmp tag.

Also, whenever you run a docker run command with a volume, a new volume is cached (seen with docker volume ls) which eats up a ton of storage over time without cleanup. An extremely common case with container development is reusing a set of volumes. Is there no way to predefine a set of host-to-container mapping and reference it rather than redefine each volume, kind of like docker network create.

2

When you use VOLUME in your Dockerfile (or build --volume), you are declaring that containers created from the resulting image must have a volume mounted on the specified path. Hence, create and run actually create anonymous volumes if an existing one does not already exist.

You can use volume create to create a named volume ahead of time, and mount it when you create containers. Just like network create.