Ceph Object - cephobject#

Ceph is an open-source storage platform that stores its data in a storage cluster based on RADOS. It is highly scalable and, as a distributed system without a single point of failure, very reliable.

Ceph provides different components for block storage and for file systems.

Ceph Object Gateway is an object storage interface built on top of librados to provide applications with a RESTful gateway to Ceph Storage Clusters. It provides object storage functionality with an interface that is compatible with a large subset of the Amazon S3 RESTful API.

Terminology#

Ceph uses the term object for the data that it stores. The daemon that is responsible for storing and managing data is the Ceph OSD. Ceph’s storage is divided into pools, which are logical partitions for storing objects. They are also referred to as data pools, storage pools or OSD pools.

A Ceph Object Gateway consists of several OSD pools and one or more Ceph Object Gateway daemon (radosgw) processes that provide object gateway functionality.

cephobject driver in LXD#

Note

The cephobject driver can only be used for buckets.

For storage volumes, use the Ceph or CephFS drivers.

Unlike other storage drivers, this driver does not set up the storage system but assumes that you already have a Ceph cluster installed.

You must set up a radosgw environment beforehand and ensure that its HTTP/HTTPS endpoint URL is reachable from the LXD server or servers. See Manual Deployment for information on how to set up a Ceph cluster and Ceph Object Gateway on how to set up a radosgw environment.

The radosgw URL can be specified at pool creation time using the cephobject.radosgw.endpoint option.

LXD uses the radosgw-admin command to manage buckets. So this command must be available and operational on the LXD servers.

This driver also behaves differently than other drivers in that it provides remote storage. As a result and depending on the internal network, storage access might be a bit slower than for local storage. On the other hand, using remote storage has big advantages in a cluster setup, because all cluster members have access to the same storage pools with the exact same contents, without the need to synchronize storage pools.

LXD assumes that it has full control over the OSD storage pool. Therefore, you should never maintain any file system entities that are not owned by LXD in a LXD OSD storage pool, because LXD might delete them.

Configuration options#

The following configuration options are available for storage pools that use the cephobject driver and for storage buckets in these pools.

Storage pool configuration#

Key

Type

Default

Description

cephobject.bucket.name_prefix

string

-

Prefix to add to bucket names in Ceph

cephobject.cluster_name

string

ceph

The Ceph cluster to use

cephobject.radosgw.endpoint

string

-

URL of the radosgw gateway process

cephobject.radosgw.endpoint_cert_file

string

-

Path to the file containing the TLS client certificate to use for endpoint communication

cephobject.user.name

string

admin

The Ceph user to use

volatile.pool.pristine

string

true

Whether the radosgw lxd-admin user existed at creation time

Storage bucket configuration#

Key

Type

Default

Description

size

string

-

Quota of the storage bucket