Now run 'docker inspect test-vol'.
You will see lot on the output, look for _Mounts_ section.
"Mounts": [
{
"Type": "volume",
"Name": "6e0e215327c8497ac2f08fe4ca57b939eef7737e851b5e9b368f943d6a284a3b",
"Source": "/var/lib/docker/volumes/6e0e215327c8497ac2f08fe4ca57b939eef7737e851b5e9b368f943d6a284a3b/_data",
"Destination": "new-vol",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
}
]
This shows that the mount is a volume, it shows the correct source and destination, and that the mount is read-write.

Dockerfile