--name option to name the volume is missing for cifs-volume-plugin

[christian-weiss]

If i run:

docker volume create -d trajano/cifs-volume-plugin --opt cifsopts=uid=1000 192.168.8.4/Downloads

the a value with the name "192.168.8.4/Downloads" will be created (username, password and domain came from /root/credentials/default):

docker volume ls
DRIVER                              VOLUME NAME
trajano/cifs-volume-plugin:latest   192.168.8.4/Downloads

To show you that this is not an allowed name i delete this volume and then try to mount this non-existing volume (this prints out the allowed characters for volume names):

docker run -d --name helloshare -v 192.168.8.4/Downloads:/testvolumesmb strm/helloworld-http
docker: Error response from daemon: create 192.168.8.4/Downloads: "192.168.8.4/Downloads" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed. If you intended to pass a host directory, use absolute path.
See 'docker run --help'.

means the "/" is not allowed. Would be nice if you generate a better volume name and add support for "--name" option to define a custom volume name.

[christian-weiss]

docker version
Client:
 Version:           18.06.1-ce
 API version:       1.38
 Go version:        go1.10.3
 Git commit:        e68fc7a
 Built:             Tue Aug 21 17:25:03 2018
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.06.1-ce
  API version:      1.38 (minimum version 1.12)
  Go version:       go1.10.3
  Git commit:       e68fc7a
  Built:            Tue Aug 21 17:23:29 2018
  OS/Arch:          linux/amd64
  Experimental:     false

[trajano]

What needs to happen is around

https://github.com/trajano/docker-volume-plugins/blob/master/cifs-volume-plugin/main.go#L29

shareName, shareNameInOpts := req.Options["share"]
if ! shareNameInOpts {
  shareName = "//" + req.Name
}

Then https://github.com/trajano/docker-volume-plugins/blob/master/cifs-volume-plugin/main.go#L43

return []string{"-t", "cifs", "-o", strings.Join(cifsoptsArray, ","), shareName}

Or something like that.

I'm free to take in a PR for this but needs to have the documentation updated as well.