Git-Annex Mass Downloader and Metadata-er
Project description
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gamdam is the Git-Annex Mass Downloader and Metadata-er. It takes a stream of JSON Lines describing what to download and what metadata each file has, downloads them in parallel to a git-annex repository, attaches the metadata using git-annex’s metadata facilities, and commits the results.
This program was written as an experiment/proof-of-concept for a larger program and is no longer maintained. However, the author has also produced a Rust translation of this program at <https://github.com/jwodder/gamdam-rust> which is currently being maintained.
Installation
gamdam requires Python 3.8 or higher. Just use pip for Python 3 (You have pip, right?) to install gamdam and its dependencies:
python3 -m pip install gamdam
gamdam also requires git-annex v10.20220222 or higher to be installed separately in order to run.
Usage
gamdam [<options>] [<input-file>]
gamdam reads a series of JSON entries from a file (or from standard input if no file is specified) following the input format described below. It feeds the URLs and output paths to git-annex addurl, and once each file has finished downloading, it attaches any listed metadata and extra URLs using git-annex metadata and git-annex registerurl, respectively.
Note that the latter step can only be performed on files tracked by git-annex; if you, say, have configured git-annex to not track text files, then any text files downloaded will not have any metadata or alternative URLs registered.
Options
- --addurl-opts OPTIONS
Extra options to pass to the git-annex addurl command. Note that multiple options & arguments need to be quoted as a single string, which must also use proper shell quoting internally; e.g., --addurl-opts="--user-agent 'gamdam via git-annex'".
- -C DIR, --chdir DIR
The directory in which to download files; defaults to the current directory. If the directory does not exist, it will be created. If the directory does not belong to a Git or git-annex repository, it will be initialized as one.
- -F FILE, --failures FILE
If any files fail to download, write their input records back out to FILE
- -J INT, --jobs INT
Number of parallel jobs for git-annex addurl to use; by default, the process is instructed to use one job per CPU core.
- -l LEVEL, --log-level LEVEL
Set the log level to the given value. Possible values are “CRITICAL”, “ERROR”, “WARNING”, “INFO”, “DEBUG” (all case-insensitive) and their Python integer equivalents. [default: INFO]
- -m TEXT, --message TEXT
The commit message to use when saving. This may contain a {downloaded} placeholder which will be replaced with the number of files successfully downloaded.
- --no-save-on-fail
Don’t commit the downloaded files if any files failed to download
- --save, --no-save
Whether to commit the downloaded files once they’ve all been downloaded [default: --save]
Input Format
Input is a series of JSON objects, one per line (a.k.a. “JSON Lines”). Each object has the following fields:
- url
(required) A URL to download
- path
(required) A relative path where the contents of the URL should be saved. If an entry with a given path is encountered while another entry with the same path is being downloaded, the later entry is discarded, and a warning is emitted.
If a file already exists at a given path, git-annex will try to register the URL as an additional location for the file, failing if the resource at the URL is not the same size as the extant file.
- metadata
A collection of metadata in the form used by git-annex metadata, i.e., a dict mapping key names to lists of string values.
- extra_urls
A list of alternative URLs for the resource, to be attached to the downloaded file with git-annex registerurl.
If a given input line is invalid, it is discarded, and an error message is emitted.
Library Usage
gamdam can also be used as a Python library. It exports the following:
async def download(
repo: pathlib.Path,
objects: AsyncIterator[Downloadable],
jobs: Optional[int] = None,
addurl_opts: Optional[List[str]] = None,
subscriber: Optional[anyio.abc.ObjectSendStream[DownloadResult]] = None,
) -> ReportDownload the items yielded by the async iterator objects to the directory repo (which must be part of a git-annex repository) and set their metadata. jobs is the number of parallel jobs for the git-annex addurl process to use; a value of None means to use one job per CPU core. addurl_opts contains any additional arguments to append to the git-annex addurl command.
If subscriber is supplied, it will be sent a DownloadResult (see below) for each completed download, both successful and failed. This can be used to implement custom post-processing of downloads.
class Downloadable(pydantic.BaseModel):
path: pathlib.Path
url: pydantic.AnyHttpUrl
metadata: Optional[Dict[str, List[str]]] = None
extra_urls: Optional[List[pydantic.AnyHttpUrl]] = NoneDownloadable is a pydantic model used to represent files to download; see Input Format above for the meanings of the fields.
class DownloadResult(pydantic.BaseModel):
downloadable: Downloadable
success: bool
key: Optional[str] = None
error_messages: Optional[List[str]] = NoneDownloadResult is a pydantic model used to represent a completed download. It contains the original Downloadable, a flag to indicate download success, the downloaded file’s git-annex key (only set if the download was successful and the file is tracked by git-annex) and any error messages from the addurl process (only set if the download failed).
@dataclass
class Report:
downloaded: int
failed: intReport is used as the return value of download(); it contains the number of files successfully downloaded and the number of failed downloads.
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