394eea0231
This driver implements the storagedriver.StorageDriver interface and
uses Ceph Object Storage as storage backend.
Since RADOS is an object storage and no hierarchy notion, the
following convention is used to keep the filesystem notions stored in
this backend:
* All the objects data are stored with opaque UUID names prefixed
(e.g. "blob:d3d232ff-ab3a-4046-9ab7-930228d4c164).
* All the hierarchy information are stored in rados omaps, where the
omap object identifier is the virtual directory name, the keys in
a specific are the relative filenames and the values the blob
object identifier (or empty value for a sub directory).
e.g. For the following hierarchy:
/directory1
/directory1/object1
/directory1/object2
/directory1/directory2/object3
The omap "/directory1" will contains the following key / values:
- "object1" "blob:d3d232ff-ab3a-4046-9ab7-930228d4c164"
- "object2" "blob:db2e359d-4af0-4bfb-ba1d-d2fd029866a0"
- "directory2" ""
The omap "/directory1/directory2" will contains:
- "object3" "blob:9ae2371c-81fc-4945-80ac-8bf7f566a5d9"
* The MOVE is implemented by changing the reference to a specific
blob in its parent virtual directory omap.
This driver stripes rados objects to a fixed size (e.g. 4M). The idea
is to keep small objects (as done by RBD on the top of RADOS) that
will be easily synchronized accross OSDs. The information of the
original object (i.e total size of the chunks) is stored as a Xattr
in the first chunk object.
Signed-off-by: Vincent Giersch <vincent.giersch@ovh.net>
38 lines
1.3 KiB
Markdown
38 lines
1.3 KiB
Markdown
<!--GITHUB
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page_title: Ceph RADOS storage driver
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page_description: Explains how to use the Ceph RADOS storage driver
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page_keywords: registry, service, driver, images, storage, ceph, rados
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IGNORES-->
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# Ceph RADOS storage driver
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An implementation of the `storagedriver.StorageDriver` interface which uses
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[Ceph RADOS Object Storage][rados] for storage backend.
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## Parameters
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The following parameters must be used to configure the storage driver
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(case-sensitive):
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* `poolname`: Name of the Ceph pool
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* `username` *optional*: The user to connect as (i.e. admin, not client.admin)
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* `chunksize` *optional*: Size of the written RADOS objects. Default value is
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4MB (4194304).
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This drivers loads the [Ceph client configuration][rados-config] from the
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following regular paths (the first found is used):
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* `$CEPH_CONF` (environment variable)
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* `/etc/ceph/ceph.conf`
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* `~/.ceph/config`
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* `ceph.conf` (in the current working directory)
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## Developing
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To include this driver when building Docker Distribution, use the build tag
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`include_rados`. Please see the [building documentation][building] for details.
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[rados]: http://ceph.com/docs/master/rados/
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[rados-config]: http://ceph.com/docs/master/rados/configuration/ceph-conf/
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[building]: https://github.com/docker/distribution/blob/master/docs/building.md#optional-build-tags
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