AWS Durable Execution SDK for Python

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Build reliable, long-running AWS Lambda workflows with checkpointed steps, waits, callbacks, and parallel execution.

✨ Key Features

• Automatic checkpointing - Resume execution after Lambda pauses or restarts
• Durable steps - Run work with retry strategies and deterministic replay
• Waits and callbacks - Pause for time or external signals without blocking Lambda
• Parallel and map operations - Fan out work with configurable completion criteria
• Child contexts - Structure complex workflows into isolated subflows
• Replay-safe logging - Use context.logger for structured, de-duplicated logs
• Local and cloud testing - Validate workflows with the testing SDK

📦 Packages

Package	Description	Version
aws-durable-execution-sdk-python	Execution SDK for Lambda durable functions
aws-durable-execution-sdk-python-testing	Local/cloud test runner and pytest helpers

🚀 Quick Start

Install the execution SDK:

pip install aws-durable-execution-sdk-python

Create a durable Lambda handler:

from aws_durable_execution_sdk_python import (
    DurableContext,
    StepContext,
    durable_execution,
    durable_step,
)
from aws_durable_execution_sdk_python.config import Duration

@durable_step
def validate_order(step_ctx: StepContext, order_id: str) -> dict:
    step_ctx.logger.info("Validating order", extra={"order_id": order_id})
    return {"order_id": order_id, "valid": True}

@durable_execution
def handler(event: dict, context: DurableContext) -> dict:
    order_id = event["order_id"]
    context.logger.info("Starting workflow", extra={"order_id": order_id})

    validation = context.step(validate_order(order_id), name="validate_order")
    if not validation["valid"]:
        return {"status": "rejected", "order_id": order_id}

    # simulate approval (real world: use wait_for_callback)
    context.wait(duration=Duration.from_seconds(5), name="await_confirmation")

    return {"status": "approved", "order_id": order_id}

📚 Documentation

• AWS Documentation - Official AWS Lambda durable functions guide
• Documentation index - SDK Overview and navigation

New to durable functions?

• Getting started guide - Build your first durable function

Core operations:

• Steps - Execute code with automatic checkpointing and retry support
• Wait operations - Pause execution without blocking Lambda resources
• Callbacks - Wait for external systems to respond
• Invoke operations - Call other durable functions and compose workflows
• Child contexts - Organize complex workflows into isolated units
• Parallel operations - Run multiple operations concurrently
• Map operations - Process collections in parallel with batching
• Logger integration - Add structured logging to track execution

Advanced topics:

• Error handling - Handle failures and implement retry strategies
• Testing modes - Run tests locally or against deployed Lambda functions
• Testing patterns - Practical testing examples
• Serialization - Customize how data is serialized in checkpoints

Architecture:

• Architecture diagrams - Class diagrams and concurrency flows

API reference:

• API reference docs are in progress. Use the core operation docs above for now.

💬 Feedback & Support

• Bug report
• Feature request
• Documentation feedback
• Contributing guide

📄 License

See the LICENSE file for our project's licensing.