Docker volumes are free-floating filesystems. They don’t have to be connected to a particular container. You can use volumes mounted from data-only containers for portability. As of Docker 1.9.0, Docker has named volumes which replace data-only containers. Consider using named volumes to implement it rather than data containers.

Lifecycle

• docker volume create
• docker volume rm

Info

• docker volume ls
• docker volume inspect

Volumes are useful in situations where you can’t use links (which are TCP/IP only). For instance, if you need to have two docker instances communicate by leaving stuff on the filesystem.

You can mount them in several docker containers at once, using docker run --volumes-from.

Because volumes are isolated filesystems, they are often used to store state from computations between transient containers. That is, you can have a stateless and transient container run from a recipe, blow it away, and then have a second instance of the transient container pick up from where the last one left off.

See advanced volumes for more details. Container42 is also helpful.

You can map MacOS host directories as docker volumes:

docker run -v /Users/wsargent/myapp/src:/src

You can use remote NFS volumes if you’re feeling brave.

You may also consider running data-only containers as described here to provide some data portability.

Be aware that you can mount files as volumes.