refactoring-serverless

SERVERLESS DAYS TOKYO 2023 – REFACTORING SERVERLESS © 2023, Amazon
Web Services, Inc. or its affiliates. All rights reserved. © 2023, Amazon Web Services, Inc. or its affiliates. All rights reserved. 淡路大輔アマゾンウェブサービスジャパン合同会社ソリューションアーキテクト S E R V E R L E S S D A Y S T O K Y O 2 0 2 3 Refactoring serverless ※ 本資料に記載されているプログラムはプレゼンテーション向けに簡略化された表記である場合があります

Web Services, Inc. or its affiliates. All rights reserved. 5 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Introducing AWS Lambda Available in Tokyo 5 Minute Functions Access resources within a VPC Up to 15 minutes Custom runtimes Provisioned concurrency Supports EFS, container images Lambda extentions 10GB Memory Graviton2 10GB /tmp function URL Lambda SnapStart Response payload streaming 10th Anniversary Introducing Amazon API Gateway Introducing Amazon EventBridge Introducing AWS Step Functions 2004 Introducing Amazon SQS 2006 Introducing Amazon S3 ~ 2006 Support SQS as Event Source Step Functions Express Workflows Step Functions AWS SDK Integration

Web Services, Inc. or its affiliates. All rights reserved. Serverless Refactoring Pattern 15 Extract send message (using Lambda Destination) AWS Step Functions Service Integration Send Message via EventBridge Pipes 02 03 01

Web Services, Inc. or its affiliates. All rights reserved. Extract send message (using Lambda Destination) 17 AWS Lambda Amazon SQS (success) Amazon SNS async invocation Amazon SQS (failure) https://aws.amazon.com/jp/blogs/compute/introducing-aws-lambda-destinations/

Web Services, Inc. or its affiliates. All rights reserved. Extract send message (using Lambda Destination) 18 AWS Lambda import { SQS } from "aws-sdk"; export const handler = async (event) => { const result = // Business Logic const params = { QueueUrl: process.env.QUEUE_URL, MessageBody: result, }; await sqs.sendMessage(params).promise(); };

Web Services, Inc. or its affiliates. All rights reserved. Extract send message (using Lambda Destination) 19 AWS Lambda QueueUrl: process.env.QUEUE_URL, await sqs.sendMessage(params).promise(); ・トポロジーが環境変数に隠れている・アプリケーションコードにロジックとサービスの依存関係が混在

Web Services, Inc. or its affiliates. All rights reserved. Extract send message (using Lambda Destination) 20 AWS Lambda AWS Lambda export const handler = async (event) => { const result = // Business Logic return { message: result }; }; AWS CDK new Function(this, ”orderFunction", { runtime: Runtime.NODEJS_18_X, code: Code.fromAsset("app/functions//index.ts”), handler: ”order.handler", onSuccess: new SqsDestination(queue), }); Original Refactored ・トポロジーは CDK コードに集約される・アプリケーションコードには、ロジックのみ記述される import { SQS } from "aws-sdk"; export const handler = async (event) => { const result = // Business Logic const params = { QueueUrl: process.env.QUEUE_URL, MessageBody: result, }; await sqs.sendMessage(params).promise(); }; ・トポロジーが環境変数に隠れている・アプリケーションコードにロジックとサービスの依存関係が混在

Web Services, Inc. or its affiliates. All rights reserved. Extract send message – Error handling 21 AWS Lambda AWS Lambda export const handler = async (event) => { const result = // Business Logic return { message: result }; }; AWS CDK new Function(this, ”orderFunction", { runtime: Runtime.NODEJS_18_X, code: Code.fromAsset("app/functions//index.ts”), handler: ”order.handler", onSuccess: new SqsDestination(queue), onFailure: new SqsDestination(failureQueue), }); Original Refactored import { SQS } from "aws-sdk"; export const handler = async (event) => { try { const result = // Business Logic const params = { QueueUrl: process.env.QUEUE_URL, MessageBody: result, }; await sqs.sendMessage(params).promise(); } catch (e) { const error = // Error handling Logic await sqs.sendMessage(error).promise(); } };

Web Services, Inc. or its affiliates. All rights reserved. Extract send message – 注意するポイント 22 ・Lambda の非同期呼び出しのみサポート・SQS への送信処理は Function の処理の最後に実⾏される複数の Queue に送信するシーンでは活⽤できない複数の Queue に “同⼀” メッセージを送信したい場合は SNS を Destination の送信先に設定し、Fan Out する・SDK による実装と⽐べて、SQS への送信メッセージの形式が変更される SQS Message using AWS SDK SQS Message using Lambda Destination

Web Services, Inc. or its affiliates. All rights reserved. AWS Step Functions Service Integration 25 AWS Step Functions workflow Lambda: Invoke Detect Labels start Pass state Extract Name Choice state Is Pizza? Fail state Failed Succeed state Passed End Lambda Function Amazon Rekognition image Amazon S3 Image Bucket Detect Labels API AWS Step Functions workflow Rekognition: Detect Object start Pass state Extract Name Choice state Is Pizza? Fail state Failed Succeed state Passed End Amazon Rekognition image Amazon S3 Image Bucket AWS Step Functions から直接 AWS サービスの API をコールする

Web Services, Inc. or its affiliates. All rights reserved. AWS Step Functions Service Integration 26 ・ランタイム要素（Lambda）を無くすことで、コスト・実⾏時間・複雑さを減らす Lambda の同時実⾏数消費の緩和、 15 分の timeout の壁を越えるライブラリのアップデートなどの運⽤負荷も軽減する・余分なサービスホップを排除することで、レイテンシーを減らす

Web Services, Inc. or its affiliates. All rights reserved. AWS Lambda 27 const handler = async (event) => { const result = await rekognition.detectLabels({ Image: { S3Object: { Bucket: event.s3Bucket, Name: event.imageName } }, }); }; AWS CDK const detectObjectLambda = new lambda.Function(this, {…}); const detectObject = new tasks.LambdaInvoke(this, "Detect Object", { lambdaFunction: detectObjectLambda, payload: sfn.TaskInput.fromObject({ s3Bucket: imageBucket.bucketName, imageName: this.IMAGE_TO_LABEL, }), outputPath: "$.Payload", }); Original AWS Step Functions Service Integration

Web Services, Inc. or its affiliates. All rights reserved. AWS Lambda 28 const result = await rekognition.detectLabels({ Bucket: event.s3Bucket, Name: event.imageName } AWS CDK const detectObjectLambda = new lambda.Function(this, {…}); Glue Code としての Lambda Step Functions workflow だけで完結しない複雑さ Lambda コードにトポロジーが隠蔽されてしまう Original AWS Step Functions Service Integration

Web Services, Inc. or its affiliates. All rights reserved. AWS Lambda 29 const handler = async (event) => { const result = await rekognition.detectLabels({ Image: { S3Object: { Bucket: event.s3Bucket, Name: event.imageName } }, }); }; AWS CDK const detectObjectLambda = new lambda.Function(this, {…}); const detectObject = new tasks.LambdaInvoke(this, "Detect Object", { lambdaFunction: detectObjectLambda, payload: sfn.TaskInput.fromObject({ s3Bucket: imageBucket.bucketName, imageName: this.IMAGE_TO_LABEL, }), outputPath: "$.Payload", }); AWS CDK const detectObject = new tasks.CallAwsService(this,””, { service: "rekognition", action: "detectLabels", parameters: { Image: { S3Object: { Bucket: imageBucket.bucketName, Name: this.IMAGE_TO_LABEL, }, }, }, … }); AWS Lambda 不要 Original Refactored AWS Step Functions Service Integration

Web Services, Inc. or its affiliates. All rights reserved. Send Message via EventBridge Pipes 31 DynamoDB にドメインイベントを保存してから、 EventBridge にイベントを送信する Original Lambda Application EventBridge DynamoDB Lambda Function Table Event Custom event bus Integration ・トポロジーが環境変数に隠れている（DynamoDB テーブル名, Event Bus 名など） Rollback どうする？・複数サービスへの通信が、同じトランザクションスコープではない

Web Services, Inc. or its affiliates. All rights reserved. Send Message via EventBridge Pipes 32 Stream Pipes Original Lambda Application EventBridge Integration DynamoDB Lambda Function Table Event Custom event bus Refactored EventBridge Lambda Application EventBridge DynamoDB Lambda Function Table Event Custom event bus Integration

Web Services, Inc. or its affiliates. All rights reserved. Send Message via EventBridge Pipes 33 ・ビジネスロジックの明確化 Event Bridge への送信ロジックがアプリケーションコードから排除される・トポロジーの明確化イベントの送信先は Lambda Function の環境変数で指定せず⾃動化コード（AWS CDK, CloudFormation など）に委譲される・トランザクションの整合性保証 Lambda のエラーハンドリングやロールバック実装を簡略化・DynamoDB Streams による dedupe 同じ Item を put しても DDB Strems は最初の変更のみ Capture する

Web Services, Inc. or its affiliates. All rights reserved. “Lambda-lith” 35 AWS Lambda Amazon DynamoDB Amazon API Gateway Client /* /create /update /delete ルーティングロジックを内包した Function ・セキュリティ（IAM Role）・パフォーマンス設定（メモリ、CPU）・クォータ（同時実⾏数など）・スケーリング Function 単位に適⽤される設定

Web Services, Inc. or its affiliates. All rights reserved. delete.js “Nano Lambda” 38 Amazon DynamoDB Amazon API Gateway Client /create /update /delete import { DynamoDB } from "aws-sdk"; const dynamodb = new DynamoDB(); export const handler = async (event: any) => { const params = { TableName: "serverless-days-tokyo-2023", Key: { id: { S: event.id }, }, }; try { const data = await dynamodb.getItem(params).promise(); return { body: JSON.stringify(data) }; } catch (err) { return { error: err }; } }; update.js import { DynamoDB } from "aws-sdk"; const dynamodb = new DynamoDB(); export const handler = async (event: any) => { const params = { TableName: "serverless-days-tokyo-2023", Key: { id: { S: event.id }, }, }; try { const data = await dynamodb.getItem(params).promise(); return { body: JSON.stringify(data) }; } catch (err) { return { error: err }; } }; create.js import { DynamoDB } from "aws-sdk"; const dynamodb = new DynamoDB(); export const handler = async (event: any) => { const params = { TableName: "serverless-days-tokyo-2023", Key: { id: { S: event.id }, name: { S: event.name }, }, }; try { const data = await dynamodb.putItem(params).promise(); return { body: JSON.stringify(data) }; } catch (err) { return { error: err }; } };

Web Services, Inc. or its affiliates. All rights reserved. API Gateway to Step Functions 39 AWS Step Functions Express Workflow を REST API に活⽤する start What’s method? End Choice state DynamoDB GET DynamoDB PUT DynamoDB POST DynamoDB DELETE AWS Step Functions Express workflow Amazon API Gateway Client sync ・ワークフローとロジックの可視化・Lambda ランタイムの削減・コスト効率の向上 Express workflow は同期的なレスポンスが可能

Web Services, Inc. or its affiliates. All rights reserved. まとめ・単なる “Gule Code” としての Lambda をやめることで AWS プラットフォームの恩恵を最⼤化する・AWS CDK のような⾃動化コードでトポロジーを表現することで役割を明確化し、変更に柔軟なアーキテクチャにしていく・Lambda Function の粒度を⾒つめ直す “Nano Lambda” が唯⼀解ではない、”Lambda-lith” は必ずしも悪ではない 43

refactoring-serverless

refactoring-serverless

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