AWS Lambda Durable Functionsでシステム間連携を実現するCallback機能を試してみた #AWSreInvent

import { withDurableExecution } from "@aws/durable-execution-sdk-js";

  // ダミーのモック関数
  async function sendApprovalRequest(callbackId, orderId) {
    console.log(`Approval request sent for order ${orderId}`);
    console.log(`Callback ID: ${callbackId}`);
    // 実際の実装では、Slack通知やメール送信などを行う
  }

  export const handler = withDurableExecution(async (event, context) => {
    const orderId = event.orderId;

    // 1. コールバックを作成
    const [promise, callbackId] = await context.createCallback("approval", {
      timeout: { hours: 24 },
    });

    console.log("Callback is created!");

    // 2. 外部システムに承認リクエストを送信
    await sendApprovalRequest(callbackId, orderId);

    // 3. 外部からの応答を待機
    console.log("waiting...")
    const approval = await promise;

    return {
      orderId: orderId,
      status: approval.approved ? "approved" : "rejected",
      approval: approval,
    };
  });

{
  "orderId": "order-12345"
}

mkdir callback-successFunction && cd callback-successFunction
pnpm init
pnpm add @aws-sdk/client-lambda@latest

import {
  LambdaClient,
  SendDurableExecutionCallbackSuccessCommand
} from "@aws-sdk/client-lambda";

const client = new LambdaClient({ region: "us-east-2" });

export const handler = async (event) => {
  const command = new SendDurableExecutionCallbackSuccessCommand({
    FunctionName: "myDurableFunction",
    CallbackId: event.callbackId,
    Result: JSON.stringify({
      approved: true,
      approver: "john@example.com"
    })
  });

  await client.send(command);
  return { statusCode: 200, body: "Callback sent" };
};

zip -r function.zip index.mjs node_modules/

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "lambda:SendDurableExecutionCallbackSuccess",
        "lambda:SendDurableExecutionCallbackFailure"
      ],
      "Resource": "arn:aws:lambda:us-east-2:*:function:myDurableFunction"
    }
  ]
}

{
  "callbackId": "先ほどコピーしたCallback ID"
}

1. Durable Function
   └─ createCallback() でコールバックIDを生成
   └─ Slackに通知（ボタンのvalueにcallbackIdを埋め込む）
   └─ 待機...

2. Slackでユーザーが「承認」ボタンをクリック

3. Webhook Handler（API Gateway + Lambda）
   └─ SlackからのPOSTを受け取る
   └─ callbackIdを取り出す
   └─ SendDurableExecutionCallbackSuccess を呼び出す

4. Durable Function が再開！