tanbih-pipeline 0.11.13

a pipeline framework for streaming processing

a flexible stream processing framework supporting RabbitMQ, Pulsar, Kafka and Redis.

Features

• at-least-once guaranteed with acknowledgement on every message

• horizontally scalable through consumer groups

• flow is controlled in deployment, develop it once, use it everywhere

• testability provided with FILE and MEMORY input/output

Requirements

• Python 3.8

Installation

$ pip install tanbih-pipeline

You can install the required backend dependencies with:

$ pip install tanbih-pipeline[redis]
$ pip install tanbih-pipeline[kafka]
$ pip install tanbih-pipeline[pulsar]
$ pip install tanbih-pipeline[rabbitmq]
$ pip install tanbih-pipeline[azure]

If you want to support all backends, you can:

$ pip install tanbih-pipeline[full]

Producer

Producer is to be used when developing a data source in our pipeline. A source will produce output without input. A crawler can be seen as a producer.

>>> from typing import Generator
>>> from pydantic import BaseModel
>>> from pipeline import Producer as Worker, ProducerSettings as Settings
>>>
>>> class Output(BaseModel):
...     key: int
>>>
>>> class MyProducer(Worker):
...     def generate(self) -> Generator[Output, None, None]:
...         for i in range(10):
...             yield Output(key=i)
>>>
>>> settings = Settings(name='producer', version='0.0.0', description='')
>>> producer = MyProducer(settings, output_class=Output)
>>> producer.parse_args("--out-kind MEM --out-topic test".split())
>>> producer.start()
>>> [r.get('key') for r in producer.destination.results]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Processor

Processor is to be used to process input. Modification will be in-place. A processor can produce one output for each input, or no output.

>>> from pipeline import Processor as Worker, ProcessorSettings as Settings
>>>
>>> class Input(BaseModel):
...     key: int
>>>
>>> class Output(BaseModel):
...     key: int
...     processed: bool
>>>
>>> class MyProcessor(Worker):
...     def process(self, input):
...         return Output(key=input.key, processed=True)
>>>
>>> settings = Settings(name='processor', version='0.1.0', description='')
>>> processor = MyProcessor(settings, input_class=Input, output_class=Output)
>>> args = "--in-kind MEM --in-topic test --out-kind MEM --out-topic test".split()
>>> processor.parse_args(args)
>>> processor.start()

Splitter

Splitter is to be used when writing to multiple outputs. It will take a function to generate output topic based on the processing message, and use it when writing output.

>>> from pipeline import Splitter as Worker, SplitterSettings as Settings
>>>
>>> class MySplitter(Worker):
...     def get_topic(self, msg):
...         return '{}-{}'.format(self.destination.topic, msg.get('id'))
>>>
>>> settings = Settings(name='splitter', version='0.1.0', description='')
>>> splitter = MySplitter(settings)
>>> args = "--in-kind MEM --in-topic test --out-kind MEM --out-topic test".split()
>>> splitter.parse_args(args)
>>> splitter.start()

Usage

Writing a Worker

Choose Producer, Processor or Splitter to subclass from.

Environment Variables

Application accepts following environment variables (Please note, you will need to add prefix IN_, –in- and OUT_, –out- to these variables to indicate the option for input and output):

environment variable	command line argument	options
KIND	–kind	KAFKA, PULSAR, FILE
PULSAR	–pulsar	pulsar url
TENANT	–tenant	pulsar tenant
NAMESPACE	–namespace	pulsar namespace
SUBSCRIPTION	–subscription	pulsar subscription
KAFKA	–kafka	kafka url
GROUPID	–group-id	kafka group id
TOPIC	–topic	topic to read

Custom Code

Define add_arguments to add new arguments to worker.

Define setup to run initialization code before worker starts processing messages. setup is called after command line arguments have been parsed. Logic based on options (parsed arguments) goes here.

Options

Errors

The value None above is error you should return if dct or dcts is empty. Error will be sent to topic errors with worker information.

Contribute

Use pre-commit to run black and flake8

Credits

Yifan Zhang (yzhang at hbku.edu.qa)