glance_store.multi_backend module

glance_store.multi_backend.add(conf, image_id, data, size, backend, context=None, verifier=None)
glance_store.multi_backend.add_with_multihash(conf, image_id, data, size, backend, hashing_algo, scheme=None, context=None, verifier=None)
glance_store.multi_backend.check_location_metadata(val, key='')
glance_store.multi_backend.create_multi_stores(conf=<oslo_config.cfg.ConfigOpts object>, reserved_stores=None)

Registers all store modules and all schemes from the given configuration object.

Parameters:

  • conf – A oslo_config (or compatible) object

  • reserved_stores – A list of stores for the consuming service’s internal use. The list must be the same format as the enabled_backends configuration setting. The default value is None

Returns:

The number of stores configured

Raises:

glance_store.exceptions.BackendException

Configuring Multiple Backends

The backends to be configured are expected to be found in the enabled_backends configuration variable in the DEFAULT group of the object. The format for the variable is a dictionary of key:value pairs where the key is an arbitrary store identifier and the value is the store type identifier for the store.

The type identifiers must be defined in the [entry points] section of the glance_store setup.cfg file as values for the glance_store.drivers configuration. (See the default setup.cfg file for an example.) The store type identifiers for the currently supported drivers are already defined in the file.

Thus an example value for enabled_backends is:

{'store_one': 'http', 'store_two': 'file', 'store_three': 'rbd'}

The reserved_stores parameter, if included, must have the same format. There is no difference between the enabled_backends and reserved_stores from the glance_store point of view: the reserved stores are a convenience for the consuming service, which may wish to handle the two sets of stores differently.

The Default Store

If you wish to set a default store, its store identifier should be defined as the value of the default_backend configuration option in the glance_store group of the conf parameter. The store identifier, or course, should be specified as one of the keys in the enabled_backends dict. It is recommended that a default store be set.

Configuring Individual Backends

To configure each store mentioned in the enabled_backends configuration option, you must define an option group with the same name as the store identifier. The options defined for that backend will depend upon the store type; consult the documentation for the appropriate backend driver to determine what these are.

For example, given the enabled_backends example above, you would put the following in the configuration file that loads the conf object:

[DEFAULT]
enabled_backends = store_one:rbd,store_two:file,store_three:http

[store_one]
store_description = "A human-readable string aimed at end users"
rbd_store_chunk_size = 8
rbd_store_pool = images
rbd_store_user = admin
rbd_store_ceph_conf = /etc/ceph/ceph.conf

[store_two]
store_description = "Human-readable description of this store"
filesystem_store_datadir = /opt/stack/data/glance/store_two

[store_three]
store_description = "A read-only store"
https_ca_certificates_file = /opt/stack/certs/gs.cert

[glance_store]
default_backend = store_two

The store_description options may be used by a consuming service. As recommended above, this file also defines a default backend.

glance_store.multi_backend.delete(uri, backend, context=None)

Removes chunks of data from backend specified by uri.

glance_store.multi_backend.get(uri, backend, offset=0, chunk_size=None, context=None)

Yields chunks of data from backend specified by uri.

glance_store.multi_backend.get_known_schemes_for_multi_store()

Returns list of known schemes.

glance_store.multi_backend.get_size_from_uri_and_backend(uri, backend, context=None)

Retrieves image size from backend specified by uri.

glance_store.multi_backend.get_store_from_store_identifier(store_identifier)

Determine backing store from identifier.

Given a store identifier, return the appropriate store object for handling that scheme.

glance_store.multi_backend.register_store_opts(conf, reserved_stores=None)
glance_store.multi_backend.set_acls_for_multi_store(location_uri, backend, public=False, read_tenants=[], write_tenants=None, context=None)
glance_store.multi_backend.store_add_to_backend(image_id, data, size, store, context=None, verifier=None)

A wrapper around a call to each stores add() method.

This gives glance a common place to check the output.

Parameters:

  • image_id – The image add to which data is added

  • data – The data to be stored

  • size – The length of the data in bytes

  • store – The store to which the data is being added

  • context – The request context

  • verifier – An object used to verify signatures for images

  • backend – Name of the backend to store the image

Returns:

The url location of the file, the size amount of data, the checksum of the data the storage systems metadata dictionary for the location

glance_store.multi_backend.store_add_to_backend_with_multihash(image_id, data, size, hashing_algo, store, context=None, verifier=None)

A wrapper around a call to each store’s add() method that requires a hashing_algo identifier and returns a 5-tuple including the “multihash” computed using the specified hashing_algo. (This is an enhanced version of store_add_to_backend(), which is left as-is for backward compatibility.)

Parameters:

  • image_id – The image add to which data is added

  • data – The data to be stored

  • size – The length of the data in bytes

  • store – The store to which the data is being added

  • hashing_algo – A hashlib algorithm identifier (string)

  • context – The request context

  • verifier – An object used to verify signatures for images

Returns:

The url location of the file, the size amount of data, the checksum of the data, the multihash of the data, the storage system’s metadata dictionary for the location

Raises:

glance_store.exceptions.BackendException glance_store.exceptions.UnknownHashingAlgo

glance_store.multi_backend.verify_store()