Librbd (Python)

The rbd python module provides file-like access to RBD images.

Example: Creating and writing to an image

To use rbd, you must first connect to RADOS and open an IO context:

cluster = rados.Rados(conffile='my_ceph.conf')
cluster.connect()
ioctx = cluster.open_ioctx('mypool')

Then you instantiate an :class:rbd.RBD object, which you use to create the image:

rbd_inst = rbd.RBD()
size = 4 * 1024**3  # 4 GiB
rbd_inst.create(ioctx, 'myimage', size)

To perform I/O on the image, you instantiate an :class:rbd.Image object:

image = rbd.Image(ioctx, 'myimage')
data = 'foo' * 200
image.write(data, 0)

This writes ‘foo’ to the first 600 bytes of the image. Note that data cannot be :type:unicode - Librbd does not know how to deal with characters wider than a :c:type:char.

In the end, you will want to close the image, the IO context and the connection to RADOS:

image.close()
ioctx.close()
cluster.shutdown()

To be safe, each of these calls would need to be in a separate :finally block:

cluster = rados.Rados(conffile='my_ceph_conf')
try:
    cluster.connect()
    ioctx = cluster.open_ioctx('my_pool')
    try:
        rbd_inst = rbd.RBD()
        size = 4 * 1024**3  # 4 GiB
        rbd_inst.create(ioctx, 'myimage', size)
        image = rbd.Image(ioctx, 'myimage')
        try:
            data = 'foo' * 200
            image.write(data, 0)
        finally:
            image.close()
    finally:
        ioctx.close()
finally:
    cluster.shutdown()

This can be cumbersome, so the Rados, Ioctx, and Image classes can be used as context managers that close/shutdown automatically (see PEP 343). Using them as context managers, the above example becomes:

with rados.Rados(conffile='my_ceph.conf') as cluster:
    with cluster.open_ioctx('mypool') as ioctx:
        rbd_inst = rbd.RBD()
        size = 4 * 1024**3  # 4 GiB
        rbd_inst.create(ioctx, 'myimage', size)
        with rbd.Image(ioctx, 'myimage') as image:
            data = 'foo' * 200
            image.write(data, 0)

API Reference

This module is a thin wrapper around librbd.

It currently provides all the synchronous methods of librbd that do not use callbacks.

Error codes from librbd are turned into exceptions that subclass Error. Almost all methods may raise Error (the base class of all rbd exceptions), PermissionError and IOError, in addition to those documented for the method.

class rbd.RBD

This class wraps librbd CRUD functions.

clone(self, p_ioctx, p_name, p_snapname, c_ioctx, c_name, features=None, order=None, stripe_unit=None, stripe_count=None, data_pool=None)

Clone a parent rbd snapshot into a COW sparse child.

Parameters
  • p_ioctx – the parent context that represents the parent snap

  • p_name – the parent image name

  • p_snapname – the parent image snapshot name

  • c_ioctx – the child context that represents the new clone

  • c_name – the clone (child) name

  • features (int) – bitmask of features to enable; if set, must include layering

  • order (int) – the image is split into (2**order) byte objects

  • stripe_unit (int) – stripe unit in bytes (default None to let librbd decide)

  • stripe_count (int) – objects to stripe over before looping

  • data_pool (str) – optional separate pool for data blocks

Raises

TypeError

Raises

InvalidArgument

Raises

ImageExists

Raises

FunctionNotSupported

Raises

ArgumentOutOfRange

config_list(self, ioctx)

List pool-level config overrides.

Returns

ConfigPoolIterator

create(self, ioctx, name, size, order=None, old_format=False, features=None, stripe_unit=None, stripe_count=None, data_pool=None)

Create an rbd image.

Parameters
  • ioctx (rados.Ioctx) – the context in which to create the image

  • name (str) – what the image is called

  • size (int) – how big the image is in bytes

  • order (int) – the image is split into (2**order) byte objects

  • old_format (bool) – whether to create an old-style image that is accessible by old clients, but can’t use more advanced features like layering.

  • features (int) – bitmask of features to enable

  • stripe_unit (int) – stripe unit in bytes (default None to let librbd decide)

  • stripe_count (int) – objects to stripe over before looping

  • data_pool (str) – optional separate pool for data blocks

Raises

ImageExists

Raises

TypeError

Raises

InvalidArgument

Raises

FunctionNotSupported

group_create(self, ioctx, name)

Create a group.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is used

  • name (str) – the name of the group

Raises

ObjectExists

Raises

InvalidArgument

Raises

FunctionNotSupported

group_list(self, ioctx)

List groups.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

list – a list of groups names

Raises

FunctionNotSupported

group_remove(self, ioctx, name)

Delete an RBD group. This may take a long time, since it does not return until every image in the group has been removed from the group.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the group is in

  • name (str) – the name of the group to remove

Raises

ObjectNotFound

Raises

InvalidArgument

Raises

FunctionNotSupported

group_rename(self, ioctx, src, dest)

Rename an RBD group.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the group is in

  • src (str) – the current name of the group

  • dest (str) – the new name of the group

Raises

ObjectExists

Raises

ObjectNotFound

Raises

InvalidArgument

Raises

FunctionNotSupported

list(self, ioctx)

List image names.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

list – a list of image names

list2(self, ioctx)

Iterate over the images in the pool.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool the image is in

Returns

ImageIterator

migration_abort(self, ioctx, image_name, on_progress=None)

Cancel a previously started but interrupted migration.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_name (str) – the name of the image

  • on_progress (callback function) – optional progress callback function

Raises

ImageNotFound

migration_commit(self, ioctx, image_name, on_progress=None)

Commit an executed RBD image migration.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_name (str) – the name of the image

  • on_progress (callback function) – optional progress callback function

Raises

ImageNotFound

migration_execute(self, ioctx, image_name, on_progress=None)

Execute a prepared RBD image migration.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_name (str) – the name of the image

  • on_progress (callback function) – optional progress callback function

Raises

ImageNotFound

migration_prepare(self, ioctx, image_name, dest_ioctx, dest_image_name, features=None, order=None, stripe_unit=None, stripe_count=None, data_pool=None)

Prepare an RBD image migration.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_name – the current name of the image

  • dest_ioctx (rados.Ioctx) – determines which pool to migration into

  • dest_image_name (str) – the name of the destination image (may be the same image)

  • features (int) – bitmask of features to enable; if set, must include layering

  • order (int) – the image is split into (2**order) byte objects

  • stripe_unit (int) – stripe unit in bytes (default None to let librbd decide)

  • stripe_count (int) – objects to stripe over before looping

  • data_pool (str) – optional separate pool for data blocks

Raises

TypeError

Raises

InvalidArgument

Raises

ImageExists

Raises

FunctionNotSupported

Raises

ArgumentOutOfRange

migration_status(self, ioctx, image_name)

Return RBD image migration status.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_name (str) – the name of the image

Returns

dict - contains the following keys:

  • source_pool_id (int) - source image pool id

  • source_pool_namespace (str) - source image pool namespace

  • source_image_name (str) - source image name

  • source_image_id (str) - source image id

  • dest_pool_id (int) - destination image pool id

  • dest_pool_namespace (str) - destination image pool namespace

  • dest_image_name (str) - destination image name

  • dest_image_id (str) - destination image id

  • state (int) - current migration state

  • state_description (str) - migration state description

Raises

ImageNotFound

mirror_image_instance_id_list(self, ioctx)

Iterate over the mirror image instance ids of a pool.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

MirrorImageInstanceIdIterator

mirror_image_status_list(self, ioctx)

Iterate over the mirror image statuses of a pool.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

MirrorImageStatusIterator

mirror_image_status_summary(self, ioctx)

Get mirror image status summary of a pool.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

list - a list of (state, count) tuples

mirror_mode_get(self, ioctx)

Get pool mirror mode.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

int - pool mirror mode

mirror_mode_set(self, ioctx, mirror_mode)

Set pool mirror mode.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • mirror_mode (int) – mirror mode to set

mirror_peer_add(self, ioctx, cluster_name, client_name)

Add mirror peer.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is used

  • cluster_name (str) – mirror peer cluster name

  • client_name (str) – mirror peer client name

Returns

str - peer uuid

mirror_peer_bootstrap_create(self, ioctx)

Creates a new RBD mirroring bootstrap token for an external cluster.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is written

Returns

str - bootstrap token

mirror_peer_bootstrap_import(self, ioctx, direction, token)

Import a bootstrap token from an external cluster to auto-configure the mirror peer.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • direction (int) – mirror peer direction

  • token (str) – bootstrap token

mirror_peer_get_attributes(self, ioctx, uuid)

Get optional mirror peer attributes

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • uuid (str) – uuid of the mirror peer

Returns

dict - contains the following keys:

  • mon_host (str) - monitor addresses

  • key (str) - CephX key

mirror_peer_list(self, ioctx)

Iterate over the peers of a pool.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool is read

Returns

MirrorPeerIterator

mirror_peer_remove(self, ioctx, uuid)

Remove mirror peer.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is used

  • uuid (str) – peer uuid

mirror_peer_set_attributes(self, ioctx, uuid, attributes)

Set optional mirror peer attributes

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • uuid (str) – uuid of the mirror peer

  • attributes (dict) – ‘mon_host’ and ‘key’ attributes

mirror_peer_set_client(self, ioctx, uuid, client_name)

Set mirror peer client name

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • uuid (str) – uuid of the mirror peer

  • client_name (str) – client name of the mirror peer to set

mirror_peer_set_cluster(self, ioctx, uuid, cluster_name)

Set mirror peer cluster name

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is written

  • uuid (str) – uuid of the mirror peer

  • cluster_name (str) – cluster name of the mirror peer to set

mirror_site_name_get(self, rados)

Get the local cluster’s friendly site name

Parameters

rados – cluster connection

Returns

str - local site name

mirror_site_name_set(self, rados, site_name)

Set the local cluster’s friendly site name

Parameters
  • rados – cluster connection

  • site_name – friendly site name

namespace_create(self, ioctx, name)

Create an RBD namespace within a pool

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool

  • name (str) – namespace name

namespace_exists(self, ioctx, name)

Verifies if a namespace exists within a pool

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool

  • name (str) – namespace name

Returns

bool - true if namespace exists

namespace_list(self, ioctx)

List all namespaces within a pool

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool

Returns

list - collection of namespace names

namespace_remove(self, ioctx, name)

Remove an RBD namespace from a pool

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool

  • name (str) – namespace name

pool_init(self, ioctx, force)

Initialize an RBD pool :param ioctx: determines which RADOS pool :type ioctx: rados.Ioctx :param force: force init :type force: bool

pool_metadata_get(self, ioctx, key)

Get pool metadata for the given key.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is read

  • key (str) – metadata key

Returns

str - metadata value

pool_metadata_list(self, ioctx)

List pool metadata.

Returns

PoolMetadataIterator

pool_metadata_remove(self, ioctx, key)

Remove pool metadata for the given key.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is read

  • key (str) – metadata key

Returns

str - metadata value

pool_metadata_set(self, ioctx, key, value)

Set pool metadata for the given key.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool is read

  • key (str) – metadata key

  • value (str) – metadata value

pool_stats_get(self, ioctx)

Return RBD pool stats

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool

Returns

dict - contains the following keys:

  • image_count (int) - image count

  • image_provisioned_bytes (int) - image total HEAD provisioned bytes

  • image_max_provisioned_bytes (int) - image total max provisioned bytes

  • image_snap_count (int) - image snap count

  • trash_count (int) - trash image count

  • trash_provisioned_bytes (int) - trash total HEAD provisioned bytes

  • trash_max_provisioned_bytes (int) - trash total max provisioned bytes

  • trash_snap_count (int) - trash snap count

remove(self, ioctx, name, on_progress=None)

Delete an RBD image. This may take a long time, since it does not return until every object that comprises the image has been deleted. Note that all snapshots must be deleted before the image can be removed. If there are snapshots left, ImageHasSnapshots is raised. If the image is still open, or the watch from a crashed client has not expired, ImageBusy is raised.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • name (str) – the name of the image to remove

  • on_progress (callback function) – optional progress callback function

Raises

ImageNotFound, ImageBusy, ImageHasSnapshots

rename(self, ioctx, src, dest)

Rename an RBD image.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • src (str) – the current name of the image

  • dest (str) – the new name of the image

Raises

ImageNotFound, ImageExists

trash_get(self, ioctx, image_id)

Retrieve RBD image info from trash.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_id (str) – the id of the image to restore

Returns

dict - contains the following keys:

  • id (str) - image id

  • name (str) - image name

  • source (str) - source of deletion

  • deletion_time (datetime) - time of deletion

  • deferment_end_time (datetime) - time that an image is allowed to be removed from trash

Raises

ImageNotFound

trash_list(self, ioctx)

List all entries from trash.

Parameters

ioctx (rados.Ioctx) – determines which RADOS pool the image is in

Returns

TrashIterator

trash_move(self, ioctx, name, delay=0)

Move an RBD image to the trash.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • name (str) – the name of the image to remove

  • delay (int) – time delay in seconds before the image can be deleted from trash

Raises

ImageNotFound

trash_purge(self, ioctx, expire_ts=None, threshold=-1)

Delete RBD images from trash in bulk.

By default it removes images with deferment end time less than now.

The timestamp is configurable, e.g. delete images that have expired a week ago.

If the threshold is used it deletes images until X% pool usage is met.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • expire_ts (datetime) – timestamp for images to be considered as expired (UTC)

  • threshold (float) – percentage of pool usage to be met (0 to 1)

trash_remove(self, ioctx, image_id, force=False, on_progress=None)

Delete an RBD image from trash. If image deferment time has not expired PermissionError is raised.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_id (str) – the id of the image to remove

  • force (bool) – force remove even if deferment time has not expired

  • on_progress (callback function) – optional progress callback function

Raises

ImageNotFound, PermissionError

trash_restore(self, ioctx, image_id, name)

Restore an RBD image from trash.

Parameters
  • ioctx (rados.Ioctx) – determines which RADOS pool the image is in

  • image_id (str) – the id of the image to restore

  • name (str) – the new name of the restored image

Raises

ImageNotFound

version(self)

Get the version number of the librbd C library.

Returns

a tuple of (major, minor, extra) components of the librbd version

class rbd.Image(ioctx, name=None, snapshot=None, read_only=False, image_id=None)

This class represents an RBD image. It is used to perform I/O on the image and interact with snapshots.

Note: Any method of this class may raise ImageNotFound if the image has been deleted.

close(self)

Release the resources used by this image object.

After this is called, this object should not be used.

require_not_closed(self)

Checks if the Image is not closed

Raises

InvalidArgument

class rbd.SnapIterator(Image image)

Iterator over snapshot info for an image.

Yields a dictionary containing information about a snapshot.

Keys are:

  • id (int) - numeric identifier of the snapshot

  • size (int) - size of the image at the time of snapshot (in bytes)

  • name (str) - name of the snapshot

  • namespace (int) - enum for snap namespace

  • group (dict) - optional for group namespace snapshots

  • trash (dict) - optional for trash namespace snapshots