py-ezl 0.4.4

Easy ETL

ezl — Extremely Small Pipeline Library

Easy ETL -> EZL

ezl is a tiny, opinionated pipeline engine built around Tasks, queues, and optional webhook ingestion. It focuses on simplicity, predictable backpressure, and minimal Developer Experience.

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Features at a Glance

• Composable pipeline syntax:

  p = source >> process >> sink
  run(p)
  

• Four task kinds detected automatically:

  • sync
  • sync_gen (generator → many outputs per input)
  • async
  • async_gen (async generator)

• Deterministic backpressure using blocking queue.put() in worker threads.

• Webhook ingestion with:

  • FastAPI auto-generated single + batch endpoints
  • Optional Pydantic validation
  • Built-in rate limiting
  • Automatic OpenAPI schema injection
  • API key support

• Minimal, traceable logging, including a custom FLOW level (25) to visualize pull/put behavior.

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When to Use ezl

✅ Good For

• Small to medium ETL pipelines

  • text processing, event enrichment, parsing, transformations

• Offline, sequential or multi-stage workflows

  • batch jobs, file-based processing

• Lightweight streaming

  • “pipe items through tasks” with predictable backpressure

• Webhook → background processing pipelines

  • ingest data from external systems without building full infra

• Rapid prototyping

  • tiny codebase, easy to understand

• Hobby-scale or single-node data processing

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❌ Not Good For

• Distributed or large-scale data processing

  • no clustering, no partitioning, no distributed queues

• High-availability webhook ingestion

  • in-memory queue only; no persistence or replication

• Long-running or resource-hungry async workloads

  • threads + asyncio coexist but not optimized for high concurrency

• Multi-sink routing or DAGs

  • the pipeline is strictly linear: one downstream per task

• High throughput message streaming

  • no batching at the worker level, no Kafka/RabbitMQ integration

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Concept Overview

Task

A unit of computation. Created with:

@task(buffer=100, workers=3)
def my_task(x):
    return x * 2

A task can be:

• a source (no upstream)
• a worker (pulls from upstream queue)
• a sink (no downstream)

Pipeline

Linear chain of tasks:

p = source >> step1 >> step2 >> sink
run(p)

Webhook Source

Turns a task into a FastAPI server:

@webhook(path="/ingest", model=MyModel)
def incoming():
    pass

Incoming HTTP POST data is validated and queued into downstream tasks.

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Quick Example

from ezl import task, run

@task(workers=0)
def source():
    for i in range(5):
        yield i

@task(workers=2)
def double(x):
    return x * 2

@task(workers=1)
def printer(x):
    print("out:", x)

pipeline = source >> double >> printer
run(pipeline)

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Strengths

Strength	Description
Simplicity	Very small codebase, easy to extend or customize.
Predictable behavior	Blocking backpressure ensures slow sinks naturally throttle upstream.
Flexible task types	Sync, async, generators, async generators.
Webhook integration	FastAPI-based ingestion with validation and OpenAPI.
Debuggability	FLOW-level logs show item movement through the pipeline.

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Weaknesses / Limitations

Limitation	Impact
In-memory queues only	No durability; crashes lose items.
Single downstream	DAGs, branching, joining not supported.
Threads for workers	Not ideal for CPU-heavy workloads or massive scaling.
Single-process only	No clustering or distributed pipelines.
Webhook backpressure	Full queues cause immediate 503 responses.

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Installation

pip install py-ezl 

# or if you are smart
uv add py-ezl