Duron

Duron is a lightweight durable execution runtime for Python async workflows. It provides replayable execution primitives that work standalone or as building blocks for complex workflow engines.

• 🪶 Zero extra deps — Lightweight library that layers on top of asyncio; add Duron without bloating your stack.
• 🧩 Pluggable architecture — Bring your own storage or infra components and swap them without changing orchestration code.
• 🔄 Streams & signals — Model long-running conversations, live data feeds, and feedback loops with built-in primitives.
• 🐍 Python-native & typed — Type hints make replay serialization predictable, and everything feels like idiomatic Python.
• 🔭 Built-in tracing — Detailed logs help you inspect replays and surface observability data wherever you need it.

Install

Duron requires Python 3.10+.

uv pip install duron

Quickstart

Duron wraps async orchestration (@duron.durable) and effectful steps (@duron.effect) so complex workflows stay deterministic—even when they touch the outside world.

import asyncio
import random
from pathlib import Path

import duron
from duron.contrib.storage import FileLogStorage


# Effects encapsulate side effects (I/O, randomness, API calls)
@duron.effect
async def work(name: str) -> str:
    print("⚡ Preparing to greet...")
    await asyncio.sleep(2)
    print("⚡ Greeting...")
    return f"Hello, {name}!"


@duron.effect
async def generate_lucky_number() -> int:
    print("⚡ Generating lucky number...")
    await asyncio.sleep(1)
    return random.randint(1, 100)


# Durable functions orchestrate workflow logic via ctx.run()
# They're deterministically replayed from logs on resume
@duron.durable
async def greeting_flow(ctx: duron.Context, name: str) -> str:
    # Run effects concurrently - results are logged for replay
    message, lucky_number = await asyncio.gather(
        ctx.run(work, name),
        ctx.run(generate_lucky_number),
    )
    return f"{message} Your lucky number is {lucky_number}."


async def main():
    # Session manages execution and log storage
    async with duron.Session(FileLogStorage(Path("log.jsonl"))) as session:
        # Starts new workflow or resumes from existing log
        task = await session.start(greeting_flow, "Alice")
        result = await task.result()
    print(result)


if __name__ == "__main__":
    asyncio.run(main())

Next steps

• Read the getting started guide
• Explore a more advanced example with streams and signals: examples/agent.py