AWS SAMテンプレート徹底解剖：用途別ベストプラクティスで学ぶ、スケーラブルなサーバーレス開発

AWSTemplateFormatVersion: '2010-09-09' # CloudFormationのバージョン
Transform: AWS::Serverless-2016-10-31 # SAMのTransformを宣言
Description: My Serverless Application # アプリケーションの説明
Globals: # 全てのリソースに適用される共通設定
  Function: # Lambda関数に適用される共通設定
    Timeout: 30
    MemorySize: 128
    Runtime: python3.9
    Architectures:
      - x86_64
    Tracing: Active # X-Rayトレースを有効化
  Api:
    OpenApiVersion: '3.0.1'
    Cors:
      AllowHeaders: "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token,X-Amz-User-Agent'"
      AllowOrigin: "'*'"
Resources: # アプリケーションを構成するAWSリソース
  # ここにLambda関数、API Gatewayなどを定義
Outputs: # デプロイ後に参照可能な出力値
  # 例: APIエンドポイントのURLなど

Resources:
  MyApiFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: app.lambda_handler
      Events:
        ApiEvent:
          Type: Api # API Gatewayイベント
          Properties:
            Path: /items
            Method: any
            RestApiId: !Ref MyRestApi # 既存のAPI Gatewayを参照
  MyRestApi:
    Type: AWS::Serverless::Api
    Properties:
      StageName: Prod
      DefinitionBody:
        # OpenAPI (Swagger) 定義を直接記述することも可能
        # または、LambdaのEventsセクションで自動生成
      Auth:
        DefaultAuthorizer: CognitoAuthorizer # Cognito User Poolによる認証
      BinaryMediaTypes:
        - "image/jpeg"

Resources:
  S3ProcessorFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: s3_processor.lambda_handler
      Events:
        S3Event:
          Type: S3 # S3イベント
          Properties:
            Bucket: !Ref MyDataBucket
            Events: s3:ObjectCreated:*
            Filter:
              S3Key:
                Suffix: .csv # CSVファイルのみを処理
  MyDataBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-unique-data-bucket-{{resolve:ssm:/MyApp/Env/Name}}
  SQSConsumerFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: sqs_consumer.lambda_handler
      Events:
        SQSQueue:
          Type: SQS # SQSイベント
          Properties:
            Queue: !GetAtt MySQSQueue.Arn
            BatchSize: 10 # バッチ処理サイズ
  MySQSQueue:
    Type: AWS::SQS::Queue
    Properties:
      QueueName: my-app-queue

Resources:
  DailyReportGeneratorFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: report_generator.lambda_handler
      Events:
        DailySchedule:
          Type: Schedule # スケジュールイベント
          Properties:
            Schedule: cron(0 9 * * ? *) # 毎日UTC 9:00に実行
            Input: '{"report_type": "daily"}' # Lambdaに渡す入力

Resources:
  OrderProcessingStateMachine:
    Type: AWS::Serverless::StateMachine
    Properties:
      DefinitionUri: statemachine/order_processing.asl.json # State Machine定義ファイル
      DefinitionSubstitutions:
        ProcessOrderLambdaArn: !GetAtt ProcessOrderLambda.Arn
        UpdateDatabaseLambdaArn: !GetAtt UpdateDatabaseLambda.Arn
      Events:
        ApiEvent:
          Type: Api
          Properties:
            Path: /orders
            Method: post
      Policies:
        - LambdaInvokePolicy: !Ref ProcessOrderLambda
        - LambdaInvokePolicy: !Ref UpdateDatabaseLambda
  ProcessOrderLambda:
    Type: AWS::Serverless::Function
    Properties:
      Handler: process_order.lambda_handler
      # ...
  UpdateDatabaseLambda:
    Type: AWS::Serverless::Function
    Properties:
      Handler: update_db.lambda_handler
      # ...

Resources:
  WebsiteBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-static-website-{{resolve:ssm:/MyApp/Env/Name}}
      WebsiteConfiguration:
        IndexDocument: index.html
        ErrorDocument: error.html
  WebsiteBucketPolicy:
    Type: AWS::S3::BucketPolicy
    Properties:
      Bucket: !Ref WebsiteBucket
      PolicyDocument:
        Statement:
          - Effect: Allow
            Principal: '*'
            Action: s3:GetObject
            Resource: !Join ['', ['arn:aws:s3:::', !Ref WebsiteBucket, '/*']]
  WebsiteCloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Origins:
          - DomainName: !GetAtt WebsiteBucket.RegionalDomainName
            Id: S3Origin
            CustomOriginConfig:
              HTTPPort: 80
              HTTPSPort: 443
              OriginProtocolPolicy: http-only
        Enabled: 'true'
        DefaultCacheBehavior:
          TargetOriginId: S3Origin
          ViewerProtocolPolicy: redirect-to-https
          AllowedMethods: ['GET', 'HEAD', 'OPTIONS']
          CachedMethods: ['GET', 'HEAD', 'OPTIONS']
          ForwardedValues:
            QueryString: 'false'
            Cookies: {Forward: 'none'}
        ViewerCertificate:
          CloudFrontDefaultCertificate: 'true'