glance.common.utils module

System-level utilities and helper functions.

class glance.common.utils.CooperativeReader(fd)

Bases: object

An eventlet thread friendly class for reading in image data.

When accessing data either through the iterator or the read method we perform a sleep to allow a co-operative yield. When there is more than one image being uploaded/downloaded this prevents eventlet thread starvation, ie allows all threads to be scheduled periodically rather than having the same thread be continuously active.

read(length=None)

Return the requested amount of bytes, fetching the next chunk of the underlying iterator when needed.

This is replaced with cooperative_read in __init__ if the underlying fd already supports read().

class glance.common.utils.LimitingReader(data, limit, exception_class=<class 'glance.common.exception.ImageSizeLimitExceeded'>)

Bases: object

Reader designed to fail when reading image data past the configured allowable amount.

read(i)

glance.common.utils.chunkiter(fp, chunk_size=65536)

Return an iterator to a file-like obj which yields fixed size chunks

Parameters:

• fp – a file-like object

• chunk_size – maximum size of chunk

glance.common.utils.chunkreadable(iter, chunk_size=65536)

Wrap a readable iterator with a reader yielding chunks of a preferred size, otherwise leave iterator unchanged.

Parameters:

• iter – an iter which may also be readable

• chunk_size – maximum size of chunk

glance.common.utils.cooperative_iter(iter)

Return an iterator which schedules after each iteration. This can prevent eventlet thread starvation.

Parameters:

iter – an iterator to wrap

glance.common.utils.cooperative_read(fd)

Wrap a file descriptor’s read with a partial function which schedules after each read. This can prevent eventlet thread starvation.

Parameters:

fd – a file descriptor to wrap

glance.common.utils.create_mashup_dict(image_meta)

Returns a dictionary-like mashup of the image core properties and the image custom properties from given image metadata.

Parameters:

image_meta – metadata of image with core and custom properties

glance.common.utils.evaluate_filter_op(value, operator, threshold)

Evaluate a comparison operator. Designed for use on a comparative-filtering query field.

Parameters:

• value – evaluated against the operator, as left side of expression

• operator – any supported filter operation

• threshold – to compare value against, as right side of expression

Raises:

InvalidFilterOperatorValue – if an unknown operator is provided

Returns:

boolean result of applied comparison

glance.common.utils.get_image_meta_from_headers(response)

Processes HTTP headers from a supplied response that match the x-image-meta and x-image-meta-property and returns a mapping of image metadata and properties

Parameters:

response – Response to process

glance.common.utils.get_stores_from_request(req, body)

Processes a supplied request and extract stores from it

Parameters:

• req – request to process

• body – request body

Raises:

glance_store.UnknownScheme – if a store is not valid

Returns:

a list of stores

glance.common.utils.get_test_suite_socket()

glance.common.utils.image_meta_to_http_headers(image_meta)

Returns a set of image metadata into a dict of HTTP headers that can be fed to either a Webob Request object or an httplib.HTTP(S)Connection object

Parameters:

image_meta – Mapping of image metadata

glance.common.utils.is_valid_fqdn(fqdn)

Verify whether a host is a valid FQDN.

glance.common.utils.is_valid_hostname(hostname)

Verify whether a hostname (not an FQDN) is valid.

glance.common.utils.mutating(func)

Decorator to enforce read-only logic

glance.common.utils.no_4byte_params(f)

Checks that no 4 byte unicode characters are allowed in dicts’ keys/values and string’s parameters

glance.common.utils.parse_valid_host_port(host_port)

Given a “host:port” string, attempts to parse it as intelligently as possible to determine if it is valid. This includes IPv6 [host]:port form, IPv4 ip:port form, and hostname:port or fqdn:port form.

Invalid inputs will raise a ValueError, while valid inputs will return a (host, port) tuple where the port will always be of type int.

glance.common.utils.safe_mkdirs(path)

glance.common.utils.setup_remote_pydev_debug(host, port)

glance.common.utils.sort_image_locations(locations)

glance.common.utils.split_filter_op(expression)

Split operator from threshold in an expression. Designed for use on a comparative-filtering query field. When no operator is found, default to an equality comparison.

Parameters:

expression – the expression to parse

Returns:

a tuple (operator, threshold) parsed from expression

glance.common.utils.split_filter_value_for_quotes(value)

Split filter values

Split values by commas and quotes for ‘in’ operator, according api-wg.

glance.common.utils.stash_conf_values()

Make a copy of some of the current global CONF’s settings. Allows determining if any of these values have changed when the config is reloaded.

glance.common.utils.validate_import_uri(uri)

Validate requested uri for Image Import web-download.

Parameters:

uri – target uri to be validated

glance.common.utils.validate_quotes(value)

Validate filter values

Validation opening/closing quotes in the expression.