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Distributed Pipeline Framework for Python

Project description

|Build Status| # LineUp - Distributed Pipeline Framework for Python

Lineup is a redis-based
`pipeline <>`__
framework that turns horizontal scalling seamless.

It's currently providing parallelism through python threads and is
pretty useful for writing systems where the workers make lots of network

It scales horizontally, so you can simply run more workers in as many
machines you want.


.. code:: bash

easy_install curdling
curd install lineup


Lineup focus in:

1. Simplicity: easy to create otherwise complex pipelines
2. Easy-scale: just run more workers and you're good.

Defining steps

Steps must always implement the method ``consume(self, instructions)``
and always call ``self.produce()`` with it's portion of work.

Example: a pipeline that downloads files

This is a copy of the `examples <examples>`__ folder.

.. code:: python

import re
import codecs
import requests

from lineup import Step
from lineup import Pipeline

class Download(Step):
def after_consume(self, instructions):
"Done downloading %s",

def before_consume(self):
self.log("The downloader is ready")

def consume(self, instructions):
url = instructions['url']
method = instructions.get('method', 'get').lower()

http_request = getattr(requests, method)
response = http_request(url)
instructions['download'] = {
'content': response.content,
'headers': dict(response.headers),
'status_code': response.status_code,

class Cache(Step):
def after_consume(self, instructions):
self.log("Done caching %s", instructions.keys())

def before_consume(self):
self.log("The cacher is also ready")

def get_slug(self, url):
url = re.sub(r'^https?://', '', url)
url = re.sub(r'\W+', '-', url)
return url

def consume(self, instructions):
url = instructions['url']
name = self.get_slug(url)
with, 'wb', 'utf-8') as fd:
instructions['cached_at'] = {

# Defining pipelines

class SimpleUrlDownloader(Pipeline):
name = 'downloader'
steps = [Download, Cache]

Command line

When running from the command line, lineup will recursively try to
import all python files given as ``--working-dir`` argument, which
defaults to the relative equivalent to ``os.getcwd()``.

In other words it will find your stuff automatically in dir you run the
pipeline from, or from the ``--working-dir`` arg.

Type ``lineup --help`` for more info.

Listing available pipelines

LineUp scans the given working directory recursively for pipeline class
declarations, here is how you can list all the pipelines that lineup can

.. code:: bash

lineup list pipelines

Running a pipeline in foreground

.. code:: bash

# Lineup will connect to this redis
export LINEUP_REDIS_URI='redis://0@localhost:6379'

lineup downloader run --output=rpush@example-output

.. figure:: example/run.png
:alt: example/run.png

Feeding a pipeline through command line

.. code:: bash

lineup downloader push {"url": ""}

.. figure:: example/push.png
:alt: example/run.png

Feeding a pipeline programatically

.. code:: python

from lineup import JSONRedisBackend
from example.pipelines import SimpleUrlDownloader

pipeline = SimpleUrlDownloader(JSONRedisBackend)
"url": ""

Stopping all running pipelines

This broadcasts a "stop" signal in the backend.

.. code:: bash

lineup downloader stop


Install Dependencies

.. code:: bash

curd install -r development.txt

Run tests

.. code:: bash

make test

.. |Build Status| image::

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