volume labels are losts

[petrus-v]

while restoring a volume (which happens when moving volume from nodes in mlfmonde/cluster) volumes labels are lost.

To reproduce:

$ docker volume create -d anybox/buttervolume:latest --label test=True test
gle@rbx-6-any-3 ~ $ docker volume ls
DRIVER                       VOLUME NAME
anybox/buttervolume:latest   test
$ docker volume inspect test
[
    {
        "CreatedAt": "0001-01-01T00:00:00Z",
        "Driver": "anybox/buttervolume:latest",
        "Labels": {
            "test": "True"
        },
        "Mountpoint": "/var/lib/buttervolume/volumes/test",
        "Name": "test",
        "Options": {},
        "Scope": "local"
    }
]
$ buttervolume snapshot test
$ docker volume rm test
$ docker volume inspect test
[]
Error: No such volume: test
buttervolume restore test
$ docker volume inspect test
[
    {
        "CreatedAt": "0001-01-01T00:00:00Z",
        "Driver": "anybox/buttervolume:latest",
        "Labels": null,
        "Mountpoint": "/var/lib/buttervolume/volumes/test",
        "Name": "test",
        "Options": null,
        "Scope": "local"
    }
]

[ccomb]

One possible way to avoid losing labels is by storing them in a file such as /etc/buttervolume/labels.ini