Docker container not mounting data volume

Question

I've got a locally maintained Docker image that, for some reason, is not mounting the local data volume in the container.

docker run -d -v /mnt/melissadata:/usr/local/tomcat/appconf -p 7070:7070 -p 80:8080 --restart on-failure:3 --name addrgeo imagename

On my local data volume, I have a number of files the service needs, but it's unable to find them.

I know the volume is mounted.

$ lsblk
NAME    MAJ:MIN    RM    SIZE    RO    TYPE    MOUNTPOINT
xvdi    202:128    0     10G     0     disk    /mnt/melissadata

And it appears that the Docker container can see the volume...

$ docker inspect
...
"Mounts": [
  {
    "Source": "/mnt/melissadata",
    "Destination": "/usr/local/tomcat/appconf",
    "Mode": "",
    "RW": true,
    "Propagation": "rprivate"
  }
],

findmnt returns:

$ sudo findmnt -o TARGET,PROPAGATION /mnt/melissadata
TARGET           PROPAGATION
/mnt/melissadata private

Any thoughts?

Answer 1

The reason this was happening is because the Docker daemon uses devicemapper to devicemapper to back Docker's layer storage. If the volume was mounted after the Docker daemon was started, then Docker doesn't know it exists. A restart of the Docker daemon fixes it.

sudo service docker restart