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

• Free software: Apache Software License 2.0
• Documentation: https://cinderlib.readthedocs.io.

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.

• 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.

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:

$ sudo yum install -y centos-release-openstack-pike
$ 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',
                 iscsi_protocol='iscsi',
                 iscsi_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 = list(backends[0].volumes)[0]
vol.detach()

# Get the snapshot and delete it
snap = list(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