Cinder back-end support for containers

Cinder back-end support for containers (with IPSAN)
====================================================

Requirement Description:
===================

1.Presently the Nova Docker Driver doesn't support persistence the user date (use cinder back-end)when boot containers.

 Below is a proposed solution.

Design:

======

1. With this fix, the nova-docker supports --block-device-mapping and uses docker --device to mapping the host devices to the containers devices.

Code fix Description :
===============

This Fix contains one additional method and modifies the exist method.

# This method is used for connecting the bdms, and return the mapping the devices.

    def _get_guest_storage_config(self, context, block_device_info,
                                  reboot=False):

At the same time, it adds volume_drivers for the docker.
docker_volume_drivers = [
    'iscsi=novadocker.virt.docker.volume.DockerISCSIVolumeDriver',
]

# This method add support for the devices

    self._start_container(container_id, instance, network_info, devices)

Test Description:
============

Apart from the Unit test execution, below is a manual way to verify the working functionality by the tester.

1. Create a cinder volume using openstack
    #cinder create --display-name vol-test 1

/etc/cinder/cinder.conf
[lvmdriver-1]
iscsi_helper = tgtadm
volume_group = stack-volumes-lvmdriver-1
volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver
volume_backend_name = lvmdriver-1

2. Create containers useing the above VOL-ID

nova boot test-vol --flavor 2 --image cirros:latest --nic net-id=7754392d-f56e-4240-9a64-9ee5710251be --block-device-mapping vdx=$VOL-ID:::0

Note:
There is a bug in the kilo, must fix bug with two patches: one is already in kilo, another patch client is not fix yet.

https://bugs.launchpad.net/nova/+bug/1433609

The python-novaclient patch

https://review.openstack.org/#/c/165932/1

3. Verify the container device mapping

     #docker inspect CONTAINER-ID
        "Devices": [
            {
                "CgroupPermissions": "rwm",
                "PathInContainer": "/dev/vdx",
                "PathOnHost": "/dev/sdd"
            }
        ]

4. Verify the iscsi mession

    #iscsiadm -m session |grep $VOL-ID

5. Verify that the device can be used and the attach info in cinder is right.

    #dd if=/dev/vdx of=/home/c.file bs=512 count=1

[root@localhost iscsi]# cinder list
+--------------------------------------+--------+----------+------+-------------+----------+--------------------------------------+
| ID | Status | Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+--------+----------+------+-------------+----------+--------------------------------------+
| 79c9c916-583b-4e45-b73d-42be60012f23 | in-use | vol-006 | 1 | lvmdriver-1 | false | 954fb01c-8d0e-46cc-bad7-85728dc1a4df |
| c2e42831-d730-496c-8bb7-1255349baa2f | in-use | vol-test | 1 | lvmdriver-1 | false | 009ed2a5-41a7-4877-94bb-3dbc73126236 |
+--------------------------------------+--------+----------+------+-------------+----------+--------------------------------------+

Gerrit topic: https://review.openstack.org/#q,topic:bp/container-cinder-support,n,z

Addressed by: https://review.openstack.org/178500
    Cinder back-end support for containers