Unable to mount persistent volume to Docker container using Rex-Ray and VirtualBox Media storage - "Invalid managed object reference" error

Question

I'm trying to mount a data volume to a docker container using the Rex-Ray plugin. I've chosen VirtualBox Media as the storage provider.

The versions I'm using are:

• Docker 1.12.5
• Rex-Ray 0.6.3 with libStorage 0.3.5
• VirtualBox base package 5.1.12

The setup:

• One CentOS 7 VM running in VirtualBox
• Docker 1.12.5 running in the CentOS 7 VM
• Rex-Ray installed and running in the CentOS 7 VM
• Mac OS X 10.12.1 host machine

On the Mac OS host machine:

1 . I turn off VirtualBox SOAP API authentication with VBoxManage setproperty websrvauthlibrary null

2 . I start the VirtualBox SOAP API with vboxwebsrv -H 0.0.0.0 -v to allow Rex-Ray to communicate with VirtualBox

In the CentOS 7 VM I'm doing the following (as root):

1 . Start Docker with systemctl start docker

2 . Create the Rex-Ray /etc/rexray/config.yml file:

libstorage:
  service: virtualbox
  integration:
    volume:
      operations:
        mount:
          preempt: true
virtualbox:
  endpoint: http://192.168.99.1:18083
  volumePath: /Users/<username>/Volumes
  controllerName: SATA

where the endpoint is the IP on which the VirtualBox SOAP API runs on the Mac OS X host machine and volumePath is an existing folder on the Mac OS X host in which volumes will be stored after creation

This config file follows the same format found in the Dell EMC tutorial on https://github.com/codedellemc/labs/tree/master/setup-virtualbox-dockermachine

3 . Start Rex-Ray service using rexray start

4 . Create a 1GB volume with docker volume create -d rexray --name pg_data --opt=size=1

5 . Attempt to run a Postgres docker container using the official postgres image. The rexray volume created previously is mounted to the /var/lib/postgresql/data directory in the Postgres container:

docker run -dit --name pg -e POSTGRES_PASSWORD=mysecretpassword --volume-driver=rexray -v pg_data:/var/lib/postgresql/data postgres

The container fails to start and I receive the following error

Error response from daemon: VolumeDriver.Mount: {"Error":"VirtualBox error: Invalid managed object reference """}

My VirtualBox storage settings are shown in the following image:

virtualbox storage settings

Any help much appreciated

Answer 1

The problem was that the port count for the SATA controller in the VirtualBox storage settings (as shown in the image linked in the question) is set to 1 by default.

The solution was to change this count to however many volumes you think you're going to mount.

A suggested count is 30 according to the Rex-Ray docs: http://rexray.readthedocs.io/en/v0.3.3/user-guide/storage-providers/#virtualbox

The following configuration worked for me: