AWS Lambda Durable Functions

npm install @aws/durable-execution-sdk-js
npm install --save-dev @aws/durable-execution-sdk-js-testing

pip install aws-durable-execution-sdk-python
pip install aws-durable-execution-sdk-python-testing

import { withDurableExecution, DurableContext } from '@aws/durable-execution-sdk-js';

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  // Execute a step with automatic retry
  const userData = await context.step('fetch-user', async () => 
    fetchUserFromDB(event.userId)
  );

  // Wait without compute charges
  await context.wait({ seconds: 5 });

  // Process in another step
  const result = await context.step('process', async () => 
    processUser(userData)
  );

  return { success: true, data: result };
});

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

@durable_step
def fetch_user(step_ctx: StepContext, user_id: str):
    return fetch_user_from_db(user_id)

@durable_step
def process_user_data(step_ctx: StepContext, user_data: dict):
    return process_user(user_data)

@durable_execution
def handler(event: dict, context: DurableContext) -> dict:
    user_data = context.step(fetch_user(event['userId']))
    context.wait(duration=Duration.from_seconds(5))
    result = context.step(process_user_data(user_data))
    return {'success': True, 'data': result}

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  const validated = await context.step('validate', async () => 
    validateInput(event)
  );
  
  const processed = await context.step('process', async () => 
    processData(validated)
  );
  
  await context.wait('cooldown', { seconds: 30 });
  
  await context.step('notify', async () => 
    sendNotification(processed)
  );
  
  return { success: true };
});

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  const messages = [{ role: 'user', content: event.prompt }];

  while (true) {
    const { response, tool } = await context.step('invoke-model', async () =>
      invokeAIModel(messages)
    );

    if (tool == null) return response;

    const toolResult = await context.step(`tool-${tool.name}`, async () =>
      executeTool(tool, response)
    );
    
    messages.push({ role: 'assistant', content: toolResult });
  }
});

# Note: invoke_ai_model and execute_tool are decorated with @durable_step
@durable_execution
def handler(event: dict, context: DurableContext) -> str:
    messages = [{"role": "user", "content": event["prompt"]}]

    while True:
        result = context.step(invoke_ai_model(messages))

        if result.get("tool") is None:
            return result["response"]

        tool = result["tool"]
        tool_result = context.step(execute_tool(tool, result["response"]))
        messages.append({"role": "assistant", "content": tool_result})

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  const plan = await context.step('generate-plan', async () =>
    generatePlan(event)
  );

  const answer = await context.waitForCallback(
    'wait-for-approval',
    async (callbackId) => sendApprovalEmail(event.approverEmail, plan, callbackId),
    { timeout: { hours: 24 } }
  );

  if (answer === 'APPROVED') {
    await context.step('execute', async () => performAction(plan));
    return { status: 'completed' };
  }
  
  return { status: 'rejected' };
});

from aws_durable_execution_sdk_python.config import WaitForCallbackConfig

@durable_execution
def handler(event: dict, context: DurableContext) -> dict:
    # Note: generate_plan and perform_action are decorated with @durable_step
    plan = context.step(generate_plan(event))

    # Wait for external approval
    def submit_approval(callback_id: str, ctx):
        send_approval_email(event['approver_email'], plan, callback_id)

    answer = context.wait_for_callback(
        submitter=submit_approval,
        name='wait-for-approval',
        config=WaitForCallbackConfig(timeout=Duration.from_hours(24))
    )

    if answer == 'APPROVED':
        context.step(perform_action(plan))
        return {'status': 'completed'}
    
    return {'status': 'rejected'}

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  const compensations: Array<{ name: string; fn: () => Promise<void> }> = [];

  try {
    await context.step('book-flight', async () => flightClient.book(event));
    compensations.push({
      name: 'cancel-flight',
      fn: () => flightClient.cancel(event)
    });

    await context.step('book-hotel', async () => hotelClient.book(event));
    compensations.push({
      name: 'cancel-hotel',
      fn: () => hotelClient.cancel(event)
    });

    return { success: true };
  } catch (error) {
    for (const comp of compensations.reverse()) {
      await context.step(comp.name, async () => comp.fn());
    }
    throw error;
  }
});

my-durable-function/
├── src/
│   ├── handler.ts              # Main handler
│   ├── steps/                  # Step functions
│   │   ├── validate.ts
│   │   └── process.ts
│   └── utils/                  # Utilities
│       └── retry-strategies.ts
├── tests/
│   └── handler.test.ts         # Tests with LocalDurableTestRunner
├── infrastructure/
│   └── template.yaml           # SAM/CloudFormation
├── eslint.config.js            # ESLint configuration
├── jest.config.js              # Jest configuration
├── tsconfig.json               # TypeScript configuration
└── package.json

my-durable-function/
├── src/
│   ├── handler.py              # Main handler
│   ├── steps/                  # Step functions
│   │   ├── __init__.py
│   │   ├── validate.py
│   │   └── process.py
│   └── utils/
│       └── retry_strategies.py
├── tests/
│   └── test_handler.py         # Tests with DurableFunctionTestRunner
├── infrastructure/
│   └── template.yaml           # SAM/CloudFormation
└── pyproject.toml              # Project configuration

npm install --save-dev @aws/durable-execution-sdk-js-eslint-plugin

import durableExecutionPlugin from '@aws/durable-execution-sdk-js-eslint-plugin';

export default [
  {
    plugins: {
      '@aws/durable-execution-sdk-js': durableExecutionPlugin,
    },
    rules: {
      '@aws/durable-execution-sdk-js/no-nested-durable-operations': 'error',
    },
  },
];

import durableExecutionPlugin from '@aws/durable-execution-sdk-js-eslint-plugin';

export default [
  durableExecutionPlugin.configs.recommended,
  // Your other configs...
];

{
  "plugins": ["@aws/durable-execution-sdk-js-eslint-plugin"],
  "extends": ["plugin:@aws/durable-execution-sdk-js-eslint-plugin/recommended"],
  "rules": {
    "@aws/durable-execution-sdk-js-eslint-plugin/no-nested-durable-operations": "error"
  }
}

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  roots: ['<rootDir>/src'],
  testMatch: ['**/*.test.ts'],
  transform: {
    '^.+\\.ts$': 'ts-jest',
  },
  collectCoverageFrom: [
    'src/**/*.ts',
    '!src/**/*.d.ts',
  ],
};