Network: IP already in use

This error is shown because you try to use a command (like Drush) with the stack stopped (drucker stop). You need to either re-run the stack (drucker start), or shutdown it.

Network: Why IPv6 is disabled?

The IPv6 is disabled inside containers, due to internal side effects (see Docker images).

command not found

Please "source" the "load-env" file before.

$ cd drucker
$ source load-env