Cinder Library allows using storage drivers outside of Cinder
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Latest commit ead327c Jan 15, 2019

README.rst

Cinder Library

Documentation Status

Introduction

Cinder Library is a Python library that allows using storage drivers outside of Cinder.

This library is currently in Alpha stage and is primarily intended as a proof of concept at this stage. While some drivers have been manually validated most drivers have not, so there's a good chance that they could experience issues.

When using this library one should be aware that this is in no way close to the robustness or feature richness that the Cinder project provides, for detailed information on the current limitations please refer to the documentation.

Due to the limited access to Cinder backends and time constraints the list of drivers that have been manually tested are (I'll try to test more):

  • LVM with LIO
  • Dell EMC XtremIO
  • Dell EMC VMAX
  • Kaminario K2
  • Ceph/RBD
  • NetApp SolidFire

If you try the library with another storage array I would appreciate a note on the library version, Cinder release, and results of your testing.

Features

  • Use a Cinder driver without running a DBMS, Message broker, or Cinder service.
  • Using multiple simultaneous drivers on the same program.
  • Basic operations support:
    • Create volume
    • Delete volume
    • Extend volume
    • Clone volume
    • Create snapshot
    • Delete snapshot
    • Create volume from snapshot
    • Connect volume
    • Disconnect volume
    • Local attach
    • Local detach
    • Validate connector
  • Code should support multiple concurrent connections to a volume, though this has not yet been tested.
  • Metadata persistence plugin:
    • Stateless: Caller stores JSON serialization.
    • Database: Metadata is stored in a database: MySQL, PostgreSQL, SQLite...
    • Custom plugin: Metadata is stored in another metadata storage.

Demo

Example

The following example uses CentOS 7 and the Cinder LVM driver, which should be the easiest to setup and test.

First you need to setup your system.

The easiest way to set things up is using Vagrant + libvirt using the provided docker example, as it will create a small VM (1GB and 1CPU) and provision everything so we can run a Python interpreter in a cinderlib container:

$ cd examples/docker
$ vagrant up
$ vagrant ssh -c 'sudo docker exec -it cinderlib python'

If we don't want to use the example we have to setup an LVM VG to use:

$ sudo dd if=/dev/zero of=cinder-volumes bs=1048576 seek=22527 count=1
$ sudo lodevice=`losetup --show -f ./cinder-volumes`
$ sudo vgcreate cinder-volumes $lodevice
$ sudo vgscan --cache

Now we can install everything on baremetal:

$ sudo yum install -y centos-release-openstack-queens $ test -f /etc/yum/vars/contentdir || echo centos >/etc/yum/vars/contentdir $ sudo yum install -y openstack-cinder targetcli python-pip $ sudo pip install cinderlib

Or run it in a container. To be able to run it in a container we need to change our host's LVM configuration and set udev_rules = 0 and udev_sync = 0 before we start the container:

$ sudo docker run --name=cinderlib --privileged --net=host \
  -v /etc/iscsi:/etc/iscsi \
  -v /dev:/dev \
  -v /etc/lvm:/etc/lvm \
  -v /var/lock/lvm:/var/lock/lvm \
  -v /lib/modules:/lib/modules:ro \
  -v /run:/run \
  -v /var/lib/iscsi:/var/lib/iscsi \
  -v /etc/localtime:/etc/localtime:ro \
  -v /root/cinder:/var/lib/cinder \
  -v /sys/kernel/config:/configfs \
  -v /sys/fs/cgroup:/sys/fs/cgroup:ro \
  -it akrog/cinderlib:latest python

Or install things on baremetal/VM:

$ sudo yum install -y centos-release-openstack-queens
$ test -f  /etc/yum/vars/contentdir || echo centos >/etc/yum/vars/contentdir
$ sudo yum install -y openstack-cinder targetcli python-pip
$ sudo pip install cinderlib
$ sudo dd if=/dev/zero of=cinder-volumes bs=1048576 seek=22527 count=1
$ sudo lodevice=`losetup --show -f ./cinder-volumes`
$ sudo pvcreate $lodevice
$ sudo vgcreate cinder-volumes $lodevice
$ sudo vgscan --cache

Then you need to run python with a passwordless sudo user (required to control LVM and do the attach) and execute:

import cinderlib as cl
from pprint import pprint as pp

# We setup the library to setup the driver configuration when serializing
cl.setup(output_all_backend_info=True)

# Initialize the LVM driver
lvm = cl.Backend(volume_driver='cinder.volume.drivers.lvm.LVMVolumeDriver',
                 volume_group='cinder-volumes',
                 target_protocol='iscsi',
                 target_helper='lioadm',
                 volume_backend_name='lvm_iscsi')

# Show the LVM backend stats
pp(lvm.stats())

# Create a 1GB volume
vol = lvm.create_volume(1, name='lvm-vol')

# Export, initialize, and do a local attach of the volume
attach = vol.attach()

pp('Volume %s attached to %s' % (vol.id, attach.path))

# Snapshot it
snap = vol.create_snapshot('lvm-snap')

# Show the JSON string
pp(vol.jsons)

# Save the whole environment to a file
with open('cinderlib-test.txt', 'w') as f:
    f.write(cl.dumps())

# Exit python
exit()

Now we can check that the logical volume is there, exported, and attached to our system:

# lvdisplay
# targetcli ls
# iscsiadm -m session
# lsblk

And now let's run a new python interpreter and clean things up:

import cinderlib as cl

# Get the whole environment up
with open('cinderlib-test.txt') as f:
    backends = cl.load(f.read(), save=True)

# Get the volume reference we loaded from file and detach
vol = backends[0].volumes[0]
# Volume no longer knows that the attach is local, so we cannot do
# vol.detach(), but we can get the connection and use it.
conn = vol.connections[0]
# Physically detach the volume from the node
conn.detach()
# Unmap the volume and remove the export
conn.disconnect()

# Get the snapshot and delete it
snap = vol.snapshots[0]
snap.delete()

# Finally delete the volume
vol.delete()

We should confirm that the logical volume is no longer there, there's nothing exported or attached to our system:

# lvdisplay
# targetcli ls
# iscsiadm -m session
# lsblk