fpipe 0.0.18

Library for working with file-likes as piped streams

fPipe

fpipe is a simple framework for creating and running data manipulation pipelines.

The need to cache files on disk between steps becomes problematic when performance is a concern. Unix pipes are well suited for some problems, but become insufficient once things get too complex.

An example is unpacking a tar file from a remote source (e.g. s3/ftp/http) and storing it to another remote store.

One possible solution using fPipe:

import boto3
from fpipe.workflow import WorkFlow
from fpipe.gen import S3, Tar
from fpipe.file import S3File
from fpipe.meta import Path

client = boto3.client('s3')
resource = boto3.resource('s3')
bucket = 'bucket'
key = 'source.tar'

WorkFlow(
    S3(client, resource),
    Tar(),
    S3(
        client, resource, bucket=bucket,
        pathname_resolver=lambda x: f'MyPrefix/{x.meta(Path).value}'
    )
).compose(
    S3File(bucket, key)
).flush()

Installing

Framework is currently tested with Python 3.6 and above, but may work with earlier versions as well.

For AWS S3 support you will boto3

brew install python3
# apt, yum, apk...
pip3 install fpipe
# Optional
pip3 install boto3

Simple example

Calculates size and md5 of stream, while writing the stream to disk.

from fpipe.file import ByteFile
from fpipe.gen import Local, Meta
from fpipe.meta import Path, Size, MD5
from fpipe.workflow import WorkFlow

workflow = WorkFlow(
    Local(pass_through=True),
    Meta(Size, MD5)
)

sources = [
    ByteFile(b'x' * 10, Path('x.dat')),
    ByteFile(b'y' * 20, Path('y.dat'))
]

for stream in workflow.compose(sources):
    print(f'\n{"-"*46}\n')
    print("Path name:", stream.meta(Path).value)
    print("Stream content: ", stream.file.read().decode('utf-8'))
    with open(stream.meta(Path).value) as f:
        print("File content:", f.read())
    print("Stream md5:", stream.meta(MD5).value)
    print("Stream size:", stream.meta(Size).value)

Subprocess script example

Stores original stream, calculates md5, encrypts using cli, stores encrypted file, calculates md5, decrypts and stores decrypted file

from fpipe.file import ByteFile
from fpipe.gen import Local, Meta, Program
from fpipe.meta import Path, MD5
from fpipe.workflow import WorkFlow

workflow = WorkFlow(
    Meta(MD5),
    Local(pass_through=True),

    Program("gpg --batch --symmetric --passphrase 'secret'"),
    Meta(MD5),
    Local(pass_through=True, pathname_resolver=lambda x: f'{x.meta(Path).value}.gpg'),

    Program("gpg --batch --decrypt --passphrase 'secret'"),
    Meta(MD5),
    Local(pass_through=True, pathname_resolver=lambda x: f'{x.meta(Path).value}.decrypted')
)

sources = (
    ByteFile(b'x' * 10, Path('x.orig')),
    ByteFile(b'y' * 20, Path('y.orig'))
)

for f in workflow.compose(sources).flush_iter():
    print(f'\n{"-"*46}\n')
    print("Original path:", f.meta(Path, 2).value)
    print("Original md5:", f.meta(MD5, 2).value, end='\n\n')
    print("Encrypted path:", f.meta(Path, 1).value)
    print("Encrypted md5:", f.meta(MD5, 1).value, end='\n\n')
    print("Decrypted path:", f.meta(Path).value)
    print("Decrypted md5:", f.meta(MD5).value)

See unittests for more examples

Run tests and verify pypi compatibility

To run tests install tox and twine with pip, go to project root and run tox

# Create virtualenv
python3 -m venv .venv
# Activate virtualenv
source .venv/bin/activate
# Run tests
tox -e py37
# Build distribution
python setup.py sdist bdist_wheel
# Validate distribution
twine check dist/*

Built With

• Travis CI
• Codecov
• Tox

Contributing

The framework is functional, but in the early stages, so any feedback on alternatives, usefulness, api-design, etc. would be appreciated

See CONTRIBUTING.md

Versioning

• Pypi
• Github

License

This project is licensed under the MIT License - see the LICENSE.txt file for details