Most of the bdbag functional logic is available via an API. Developers who wish to incorporate bdbag into their own code can do so by importing the bdbag module and make use of the functions contained within bdbag_api.py.
The command-line interface is built upon the API in this manner and can be used as a reference implementation.
The primary Python file which contains the bdbag API functions. After installing bdbag, append the following to the top of your script.
from bdbag import bdbag_apiarchive_bag(bag_path, bag_archiver)Creates a single, serialized bag archive file from the directory specified by bag_path using the format specified by
bag_archiver. The resulting archive file is BagIt spec
compliant, i.e., complies with the rules of "Section 4: Serialization" of the
BagIt Specification.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
| bag_archiver | string |
One of the following case-insensitive string values: zip, tar, or tgz. |
| config_file | string |
A JSON file representation of configuration data that is used during bag creation and update. The format of this file is described here. |
| idempotent | boolean |
A boolean value indicating that idempotent (or reproducible) archiving is desired. Reproducible archive files are made by setting fixed modification times (unix epoch, 00:00:00 UTC, 1 January 1970 in the case of tar archives, or 00:00:00 UTC, 1 January 1980 in the case of zip archives) to all files and directory entries contained within bag archive files. When extracted with bdbag, these fixed modification times will be set to the current system time. NOTE: If an idempotently created bag archive is extracted with other software besides bdbag, it may be required to specify additional arguments to overwrite the fixed mtime in the archive file to the current system time, e.g., using -m with tar. |
Returns: string - The normalized, absolute path of the directory of the created archive file.
check_payload_consistency(bag, skip_remote=False, quiet=False)Checks if the payload files in the bag's data directory are consistent with the bag's file manifests and the bag's
fetch.txt file, if any.
| Param | Type | Description |
|---|---|---|
| bag | bag |
a bag object such as that returned by make_bag |
| skip_remote | boolean |
do not include any of the bag's remote file entries or fetch.txt entries in the check |
| quiet | boolean |
do not emit any logging messages if inconsistencies are encountered |
Returns: boolean - If all payload files can be accounted for either locally or as remote entries in fetch.txt,
and that there are no additional files present that are not listed in either fetch.txt or the bag's file manifests.
cleanup_bag(bag_path)Deletes the directory tree denoted by bag_path.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
configure_logging(level=logging.INFO, logpath=None)Set the logging level and optional file output path for log statements.
| Param | Type | Description |
|---|---|---|
| level | Python logging module level constant | The logging event filter level. |
| logpath | string |
A path to a file to redirect logging statements to. Default is stdout. |
extract_bag(bag_path, output_path=None, temp=False)Extracts the bag specified by bag_path to the based directory specified by output_path, or, if the temp parameter is specified, an operating system dependent temporary path.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
| output_path | string |
A normalized, absolute path to a base directory where the bag should be extracted. |
| temp | boolean |
A boolean value indicating whether to extract this bag to a temporary directory or not. If True, overrides the output_path variable, if specified. |
Returns: string - The normalized, absolute path of the directory where the bag was extracted.
generate_ro_manifest(bag_path, overwrite=False)Automatically create a RO manifest.json file in the metadata tagfile directory.
The bag will be introspected and metadata from bag-info.txt, along with lists of local payload files and files in fetch.txt, will be used to generate the RO manifest.
Note: the contents of the manifest.json file output by this method are limited to what can be automatically generated by introspecting the bag structure and it's metadata.
Currently, this includes only provenance members of the top-level RO object, and the list of aggregated resources (aggregates) contained within the bag.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
| overwrite | boolean |
A boolean value indicating whether to overwrite or update to any existing RO metadata/manifest.json file. |
is_bag(bag_path)Checks if the path denoted by bag_path is a directory that contains a valid bag structure.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to the bag location. |
Returns: boolean - Whether the path specified by bag_path contains a valid bag structure.
prune_bag_manifests(bag)For the given bag object, removes any file and tagfile manifests for checksums that are not listed in that object's
algs member variable.
| Param | Type | Description |
|---|---|---|
| bag | bag |
a bag object such as that returned by make_bag |
Returns: boolean - If any manifests were pruned or not.
make_bag(bag_path,
update=False,
algs=None,
prune_manifests=False,
metadata=None,
metadata_file=None,
remote_file_manifest=None,
config_file=None,
ro_metadata=None,
ro_metadata_file=None,
idempotent=None,
strict=False)Creates or updates the bag denoted by the bag_path argument.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
| algs | list |
A list of checksum algorithms to use for calculating file fixities. When creating a bag, only the checksums present in this variable will be used. When updating a bag, this function will take the union of any existing bag algorithms and what is specified by this parameter, except when the prune_manifests parameter is specified, in which case then only the algorithms specifed by this parameter will be used. |
| update | boolean |
If bag_path represents an existing bag, update it. If this parameter is not specified when invoking this function on an existing bag, the function is essentially a NOOP and will emit a logging message to that effect. |
| save_manifests | boolean |
Defaults to True. If true, saves all manifests, recalculating all checksums and regenerating fetch.txt. If false, only tagfile manifest checksums are recalculated. Use this flag as an optimization (to avoid recalculating payload file checksums) when only the bag metadata has been changed. This parameter is only meaningful during update operations, otherwise it is ignored. |
| prune_manifests | boolean |
Removes any file and tagfile manifests for checksums that are not listed in the algs variable. This parameter is only meaningful during update operations, otherwise it is ignored. |
| metadata | dict |
A dictionary of key-value pairs that will be written directly to the bag's 'bag-info.txt' file. |
| metadata_file | string |
A JSON file representation of metadata that will be written directly to the bag's 'bag-info.txt' file. The format of this metadata is described here. |
| remote_file_manifest | string |
A path to a JSON file representation of remote file entries that will be used to add remote files to the bag file manifest(s) and used to create the bag's fetch.txt. The format of this file is described here. |
| config_file | string |
A JSON file representation of configuration data that is used during bag creation and update. The format of this file is described here. |
| ro_metadata | dict |
A dictionary that will be used to serialize data into one or more JSON files into the bag's metadata directory. The format of this metadata is described here. |
| ro_metadata_file | string |
A path to a JSON file representation of RO metadata that will be used to serialize data into one or more JSON files into the bag's metadata directory. The format of this metadata is described here. |
| idempotent | boolean |
If True, date and time specific metadata such as Bagging-Date and Bagging-Time will be removed (if present) from bag-info.txt. This value defaults to False if not passed via argument. However, a global override default value of True can be enabled in the config file. NOTE: use of ro_metadata and ro_metadata_file in conjunction with idempotent is not recommended at this time due to the generated RO Metadata not being compatible with bag idempotency. |
| strict | boolean |
If True, automatically validate a newly created or updated bag for structural validity and fail if the resultant bag is invalid. This can be used to ensure that a bag is not persisted without payload file manifests. Furthermore, if this argument is True and a created output bag is not structurally valid, the bag will subsequently be reverted back to a normal directory. An updated bag will not be reverted. In either case, a BagValidationError exception is thrown. |
Returns: bag - An instantiated bagit-python bag compatible class object.
materialize(input_path,
output_path=None,
fetch_callback=None,
validation_callback=None,
keychain_file=DEFAULT_KEYCHAIN_FILE,
config_file=None,
filter_expr=None,
force=False,
**kwargs)The materialize function is a bag bootstrapper. When invoked,
it will attempt to fully reconstitute a bag by performing multiple
possible actions depending on the context of the input_path parameter.
- If
input_pathis a URL or a URI of a resolvable identifier scheme, the file referenced by this value will first be downloaded to the current working directory or the directory specified by the optionaloutput-pathparameter. - If the
input_path(or previously downloaded file) represents a local path to a supported archive format, the archive will be extracted to the directory containing the bag archive or the directory specified by the optionaloutput-pathparameter. - If the
input_path(or previously extracted file) represents a valid bag directory, any remote file references contained within the bag'sfetch.txtfile will attempt to be resolved. If theinput_pathdoes not represent a valid bag directory, the function will terminate without errors and emit a log message stating this fact. - Full validation will be run on the materialized bag. If any one of these steps fail, an error is raised.
| Param | Type | Description |
|---|---|---|
| input_path | string |
An input path that must evaluate to either a local file path, local directory path, or an actionable URL/URI. |
| output_path | string |
The base output path for staging the materialization. Defaults to the current working directory. |
| fetch_callback | function(current, total) |
A callback function where the current parameter is the current item being fetched out of the total number of items to be fetched. The callback function should return a boolean indicating whether the calling function should continue processing or interrupt. |
| validation_callback | function(current, total) |
A callback function where the current parameter is the current item being validated out of the total number of items to be validated. The callback function should return a boolean indicating whether the calling function should continue processing or interrupt. |
| keychain_file | string |
A normalized, absolute path to a keychain file. Defaults to the expansion of ~/.bdbag/keychain.json. |
| config_file | string |
A normalized, absolute path to a configuration file. Defaults to the expansion of ~/.bdbag/bdbag.json. |
| filter_expr | string |
A selective fetch filter. NOTE: if a selective fetch filter is used to materialize an incomplete bag, a BagValidationException will be thrown during validation. This may be an acceptable error in some cases. |
| force | boolean |
A boolean indicating that all files listed in fetch.txt should be retrieved, regardless of whether they already exist in the payload directory or not. Otherwise, only missing or incomplete files will be retrieved. |
| **kwargs | dict |
Unpacked keyword arguments in dictionary format. |
Raises: BagValidationError, RuntimeError if the bag could not be materialized and validated successfully.
Returns: string - The normalized, absolute path to the directory of the materialized bag.
read_metadata(metadata_file)Reads the configuration file specified by metadata_file into a dictionary object. The format of metadata_file is
described here.
| Param | Type | Description |
|---|---|---|
| metadata_file | string |
A normalized, absolute path to a metadata file. |
Returns: dict - The metadata.
resolve_fetch(bag_path,
force=False,
callback=None,
keychain_file=DEFAULT_KEYCHAIN_FILE,
config_file=None,
filter_expr=None,
**kwargs)Attempt to download files listed in the bag's fetch.txt file. The method of transfer is dependent on the protocol
scheme of the URL field in fetch.txt. Note that not all file transfer protocols are supported at this time.
Additionally, some URLs may require authentication in order to retrieve protected files. In this case, the
keychain.json configuration file must be configured with the appropriate authentication mechanism and credentials to
use for a given base URL. The documentation for keychain.json can be found here.
The argument filter_expr takes a string of the form: <column><operator><value> where:
columnis one of the following literal values corresponding to the field names infetch.txt:url,length, orfilename<operator>is a predefined token. See syntax below.valueis a string or integer
With this mechanism you can do various string-based pattern matching on filename and url. For example:
filter_expr="filename$*.txt"filter_expr="filename^*README"filter_expr="filename==data/change.log"filter_expr="filename=~(?!foo).*\.json$"filter_expr="url=*/requirements/"
The above commands will get all files ending with ".txt", all files beginning with "README", the exact file "data/change.log", files ending with ".json" but do not contain "foo" on their path, and all urls containing "/requirements/" in the url path.
You can also use length and the integer relation operators to easily limit the size of the files retrieved, for example:
filter_expr="length<=1000000"
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
| force | boolean |
A boolean value indicating whether to retrieve all listed files in fetch.txt or only those which are not currently found in the bag payload directory. |
| callback | function(current, total) |
A callback function where the current parameter is the current item being fetched out of the total number of items to be fetched. The callback function should return a boolean indicating whether the calling function should continue processing or interrupt. |
| keychain_file | string |
A normalized, absolute path to a keychain file. Defaults to the expansion of ~/.bdbag/keychain.json. |
| config_file | string |
A normalized, absolute path to a configuration file. Defaults to the expansion of ~/.bdbag/bdbag.json. |
| filter_expr | string |
A string of the form: <column><operator><value>. See syntax below. |
Returns: boolean - If all remote files were resolved successfully or not. Also returns True if the function invocation resulted in a NOOP.
revert_bag(bag_path)Revert an existing bag directory back to a normal directory, deleting all bag metadata files. Payload files in the data directory will be moved back to the directory root, and the data directory will be deleted.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory. |
validate_bag(bag_path, fast=False, config_file=bdbag.DEFAULT_CONFIG_FILE)Validates a bag archive or bag directory. If a bag archive is specified, it is first extracted to a temporary directory before validation and then the temporary directory is deleted after validation completes.
If fast is True, then only the total count of payload files and the total byte count of all files are compared to the bag's
Payload-Oxum metadata field, if present. Otherwise, checksums will be recalculated for every file present in the bag
payload directory and compared against the checksum values in the file manifest(s).
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory or bag archive file. |
| fast | boolean |
If True only check payload contents against Payload-Oxum, otherwise re-calculate checksums for all payload files. |
| config_file | string |
A normalized, absolute path to a bdbag configuration file. Uses the default configuration file if not specified. |
Raises: BagValidationError, BaggingInterruptedError, or RuntimeError if the bag fails to validate successfully.
validate_bag_profile(bag_path, profile_path=None)Validates a bag archive or bag directory against a bag profile. If a bag archive is specified, it is first extracted to a temporary directory before profile validation and then the temporary directory is deleted after profile validation completes.
If a profile_path is specified, the bag is validated against that profile. Otherwise, this function checks the bag's bag-info.txt for a valid BagIt-Profile-Identifier metadata field and attemps to resolve that field's value as a URL link to the profile.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory or bag archive file. |
| bag_profile | string |
A normalized, absolute path to a BagIt-Profile file. |
Raises: ProfileValidationError
Returns: Profile - The Profile object, if the bag passed profile validation.
validate_bag_serialization(bag_path, bag_profile)Validates a bag archive's serialization format against a bag profile's Serialization and Accept-Serialization
constraints, if any.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag archive file. |
| bag_profile | string |
A normalized, absolute path to a BagIt-Profile file. |
Raises: ProfileValidationError
validate_bag_structure(bag_path, check_remote=False)Checks a bag's structural conformance as well as payload consistency between file manifests, the filesystem, and fetch.txt.
| Param | Type | Description |
|---|---|---|
| bag_path | string |
A normalized, absolute path to a bag directory or bag archive file. |
| check_remote | boolean |
A boolean value indicating if remote files should be included in the the consistency check. |
Throws: BagValidationError - If the bag structure could not be validated.
Utility functions for the bdbag.json configuration file.
To make use of these functions, after installing bdbag append the following to the top of your script.
from bdbag.bdbag_config import <function name>bootstrap_config(config_file=DEFAULT_CONFIG_FILE, keychain_file=DEFAULT_KEYCHAIN_FILE, base_dir=None)Attempts to create the default configuration file at the location specified by config_file and the default keychain file at the location specified by keychain_file.
If the base_dir argument is specified, it will be checked to ensure the directory exists and the caller has read/write/execute permissions.
If explicit locations via the declared parameters are not provided, the base_dir will be assumed to be the system dependent expansion of ~,
and config_file will be set to ~/.bdbag/bdbag.json and keychain_file will be set to ~/.bdbag/keychain.json.
| Param | Type | Description |
|---|---|---|
| config_file | string |
A normalized, absolute path to a configuration file. Defaults to the expansion of ~/.bdbag/bdbag.json. |
| keychain_file | string |
A normalized, absolute path to a configuration file. Defaults to the expansion of ~/.bdbag/keychain.json |
| base_dir | string |
A directory path, assumed to be the base path where the files will be written. This path will be checked for access before attempting to write the files. If it is not specified, it defaults to the system-dependent expansion of ~. |
read_config(config_file, create_default=True, auto_upgrade=False)Reads the configuration file specified by config_file into a dictionary object. If the file path specified is
the default configuration file location ~/.bdbag/bdbag.json, and that file does not already exist, it is created unless create_default=False.
If auto_upgrade=True and an existing configuration file is found and is of an unknown or lesser version number than the current configuration file format, it will be upgraded to the latest version.
Any existing settings found that are forward-compatible with the current version will be preserved during the upgrade process.
| Param | Type | Description |
|---|---|---|
| config_file | string |
A normalized, absolute path to a configuration file. |
| create_default | boolean |
Automatically create the file specified by config_file if it does not already exist. |
| auto_upgrade | boolean |
Automatically upgrade the file specified by config_file if it already exists and is not the current version. |
Returns: dict - The configuration data.
write_config(config=DEFAULT_CONFIG, config_file=DEFAULT_CONFIG_FILE)Writes the configuration specified by config to the location specified by config_file.
Without arguments, creates the default configuration file bdbag.json with the default configuration template, if it does not already exist.
| Param | Type | Description |
|---|---|---|
| config_file | string |
A normalized, absolute path to a configuration file. |
upgrade_config(config_file)Upgrade an existing configuration file to the current format. If an existing configuration file is found and is of an unknown or lesser version number than the current configuration file format, it will be upgraded to the latest version. Any existing settings found that are forward-compatible with the current version will be preserved during the upgrade process.
| Param | Type | Description |
|---|---|---|
| config_file | string |
A normalized, absolute path to a configuration file. |
Some shared utility functions exist at the bdbag module level in __init__.py.
To make use of these functions, after installing bdbag append the following to the top of your script.
from bdbag import <function name>inspect_path(path)Attempts to determine if the string specified by path is a local file, local directory, or a actionable URL/URI.
Returns: is_file, is_dir, is_uri - A 3-tuple of boolean values indicating if the path is a file, directory, or URL/URI, respectively.
filter_dict(expr, entry)Evaluates the dictionary variable entry against the filter expression expr,
where expr is a string of the form: <column><operator><value>.
The set of operators is syntactically limited. See syntax below.
| Param | Type | Description |
|---|---|---|
| expr | string |
A string of the form: <column><operator><value>. See syntax below. |
| entry | dict |
A dictionary containing the data to be filtered. |
-
columnis a name of a key in the input dictionary. -
<operator>is one of the following predefined tokens:Operator Description == equal != not equal =* wildcard substring equal !* wildcard substring not equal ^* wildcard starts with $* wildcard ends with =~ regexpression matches > greater than >= greater than or equal to < less than <= less than or equal to -
valueis a string or integer
Returns: boolean - A boolean value indicating whether the target dict contained a key-value pair that matched the input expr, or not.