Is there a way to define a default mount for every container to use?
For instance mount /mnt/nfs to every container by default without needing to add the -v flag to each container.
Is there a storage driver or something that can do this? it seems like something that would be something extremely useful.
The lack of responds says: there is no such thing. Otherwise someone else would have used it already and shared the knowledge with you.
If there would be such a thing, it would be configured in the /etc/daemon.json (which supportes the same options as dockerd | Docker Documentation does)