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Cinder Library allows using storage drivers outside of Cinder.

Project description

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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.

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.

You can either use a container:

$ 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 \
  -v /run/udev:/run/udev \
  -v /etc/localtime:/etc/localtime \
  -it akrog/cinderlib 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',
                 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 = 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

History

0.2.2 (2018-07-24)

  • Features:
    • Use NOS-Brick to setup OS-Brick for non OpenStack usage.
    • Can setup persistence directly to use key-value storage.
    • Support loading objects without configured backend.
    • Support for Cinder Queens, Rocky, and Master
    • Serialization returns a compact string
  • Bug fixes:
    • Workaround for Python 2 getaddrinfo bug
    • Compatibility with requests and requests-kerberos
    • Fix key-value support set_key_value.
    • Fix get_key_value to return KeyValue.
    • Fix loading object without configured backend.

0.2.1 (2018-06-14)

  • Features:
    • Modify fields on connect method.
    • Support setting custom root_helper.
    • Setting default project_id and user_id.
    • Metadata persistence plugin mechanism
    • DB persistence plugin
    • No longer dependent on Cinder’s attach/detach code
    • Add device_attached method to update volume on attaching node
    • Support attaching/detaching RBD volumes
    • Support changing persistence plugin after initialization
    • Add saving and refreshing object’s metadata
    • Add dump, dumps methods
  • Bug fixes:
    • Serialization of non locally attached connections.
    • Accept id field set to None on resource creation.
    • Disabling of sudo command wasn’t working.
    • Fix volume cloning on XtremIO
    • Fix iSCSI detach issue related to privsep
    • Fix wrong size in volume from snapshot
    • Fix name & description inconsistency
    • Set created_at field on creation
    • Connection fields not being set
    • DeviceUnavailable exception
    • Multipath settings after persistence retrieval
    • Fix PyPi package created tests module
    • Fix connector without multipath info
    • Always call create_export and remove_export
    • iSCSI unlinking on disconnect

0.1.0 (2017-11-03)

  • First release on PyPI.

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