Getting Started

megfile - Megvii FILE library

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megfile provides a silky operation experience with different backends (currently including local file system and s3), which enable you to focus more on the logic of your own project instead of the question of “Which backend is used for this file?”

megfile provides:

  • Almost unified file system operation experience. Target path can be easily moved from local file system to s3.

  • Complete boundary case handling. Even the most difficult (or even you can’t even think of) boundary conditions, megfile can help you easily handle it.

  • Perfect type hints and built-in documentation. You can enjoy the IDE’s auto-completion and static checking.

  • Semantic version and upgrade guide, which allows you enjoy the latest features easily.

megfile‘s advantages are:

  • smart_open can open resources that use various protocols. Especially, reader / writer of s3 in megfile is implemented with multi-thread, which is faster than known competitors.

  • smart_glob is available on majority protocols. And it supports zsh extended pattern syntax of [], e.g. s3://bucket/video.{mp4,avi}.

  • All-inclusive functions like smart_exists / smart_stat / smart_sync. If you don’t find the functions you want, submit an issue.

  • Compatible with pathlib.Path interface, referring to SmartPath and other protocol classes like S3Path.

Support Protocols

  • fs(local filesystem)

  • s3

  • sftp

  • http

  • stdio

  • hdfs: pip install 'megfile[hdfs]'

Quick Start

Path string in megfile almost is protocol://path/to/file, for example s3://bucketA/key. But sftp path is a little different, format is sftp://[username[:password]@]hostname[:port]//file_path, and relative path is replace //file_path to /file_path. Here’s an example of writing a file to s3 / fs, syncing to local, reading and finally deleting it.

Functional Interface

from megfile import smart_open, smart_exists, smart_sync, smart_remove, smart_glob

# open a file in s3 bucket
with smart_open('s3://playground/megfile-test', 'w') as fp:
    fp.write('megfile is not silver bullet')

# test if file in s3 bucket exist
smart_exists('s3://playground/megfile-test')

# or in local file system
smart_exists('/tmp/playground/megfile-test')

# copy files or directories
smart_sync('s3://playground/megfile-test', '/tmp/playground/megfile-test')

# remove files or directories
smart_remove('s3://playground/megfile-test')

# glob files or directories in s3 bucket
smart_glob('s3://playground/megfile-?.{mp4,avi}')

SmartPath Interface

SmartPath has a similar interface with pathlib.Path.

from megfile.smart_path import SmartPath

path = SmartPath('s3://playground/megfile-test')
if path.exists():
    with path.open() as f:
        result = f.read(7)
        assert result == b'megfile'

Command Line Interface

$ pip install 'megfile[cli]'  # install megfile cli requirements

$ megfile --help  # see what you can do

$ megfile ls s3://playground/
$ megfile ls -l -h s3://playground/

$ megfile cat s3://playground/megfile-test

$ megfile cp s3://playground/megfile-test /tmp/playground/megfile-test

Installation

PyPI

pip3 install megfile

You can specify megfile version as well

pip3 install "megfile~=0.0"

Build from Source

megfile can be installed from source

git clone git@github.com:megvii-research/megfile.git
cd megfile
pip3 install -U .

Development Environment

git clone git@github.com:megvii-research/megfile.git
cd megfile
pip3 install -r requirements.txt -r requirements-dev.txt

Configuration

Using s3 as an example, the following describes the configuration methods. For more details, please refer to Configuration.

You can use environments and configuration file for configuration, and priority is that environment variables take precedence over configuration file.

Use environments

You can use environments to setup authentication credentials for your s3 account:

  • AWS_ACCESS_KEY_ID: access key

  • AWS_SECRET_ACCESS_KEY: secret key

  • OSS_ENDPOINT / AWS_ENDPOINT_URL_S3 / AWS_ENDPOINT_URL: endpoint url of s3

  • AWS_S3_ADDRESSING_STYLE: addressing style

Use command

You can update config file with megfile command easyly: megfile config s3 [OPTIONS] AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY

$ megfile config s3 accesskey secretkey

# for aliyun
$ megfile config s3 accesskey secretkey \
--addressing-style virtual \
--endpoint-url http://oss-cn-hangzhou.aliyuncs.com \

You can get the configuration from ~/.aws/credentials, like:

[default]
aws_secret_access_key = accesskey
aws_access_key_id = secretkey

s3 =
    addressing_style = virtual
    endpoint_url = http://oss-cn-hangzhou.aliyuncs.com

How to Contribute

  • We welcome everyone to contribute code to the megfile project, but the contributed code needs to meet the following conditions as much as possible:

    You can submit code even if the code doesn’t meet conditions. The project members will evaluate and assist you in making code changes

    • Code format: Your code needs to pass code format check. megfile uses yapf as lint tool and the version is locked at 0.27.0. The version lock may be removed in the future

    • Static check: Your code needs complete type hint. megfile uses pytype as static check tool. If pytype failed in static check, use # pytype: disable=XXX to disable the error and please tell us why you disable it.

      Note : Because pytype doesn’t support variable type annation, the variable type hint format introduced by py36 cannot be used.

      i.e. variable: int is invalid, replace it with variable  # type: int

    • Test: Your code needs complete unit test coverage. megfile uses pyfakefs and moto as local file system and s3 virtual environment in unit tests. The newly added code should have a complete unit test to ensure the correctness

  • You can help to improve megfile in many ways:

    • Write code.

    • Improve documentation.

    • Report or investigate bugs and issues.

    • If you find any problem or have any improving suggestion, submit a new issuse as well. We will reply as soon as possible and evaluate whether to adopt.

    • Review pull requests.

    • Star megfile repo.

    • Recommend megfile to your friends.

    • Any other form of contribution is welcomed.