API Gateway完全ガイド
API Gateway完全ガイド
Section titled “API Gateway完全ガイド”API Gatewayは、RESTful APIやWebSocket APIを構築・管理するサービスです。実務で使える実装例とベストプラクティスを詳しく解説します。
1. API Gatewayとは
Section titled “1. API Gatewayとは”API Gatewayの役割
Section titled “API Gatewayの役割”API Gatewayは、APIのエントリーポイントとして機能し、リクエストのルーティング、認証、レート制限、キャッシングなどを提供します。
クライアント ↓（HTTPリクエスト）API Gateway ├─ 認証・認可 ├─ レート制限 ├─ キャッシング └─ ルーティング ↓Lambda関数、EC2、その他のバックエンドなぜAPI Gatewayが必要か
Section titled “なぜAPI Gatewayが必要か”問題のある構成（API Gatewayなし）:
# 問題: 直接バックエンドにアクセス# 1. 認証・認可の実装が必要# 2. レート制限の実装が必要# 3. キャッシングの実装が必要# 4. モニタリングの実装が必要
# 問題点:# 1. 開発コストが高い# 2. 一貫性の欠如# 3. 運用負荷が高い解決: API Gatewayによる統合
# 解決: API Gatewayの使用Resources: RestApi: Type: AWS::ApiGateway::RestApi Properties: Name: MyAPI Description: My REST API
# メリット:# 1. 認証・認可の統合# 2. レート制限の統合# 3. キャッシングの統合# 4. モニタリングの統合2. REST API
Section titled “2. REST API”基本的なREST API
Section titled “基本的なREST API”Resources: RestApi: Type: AWS::ApiGateway::RestApi Properties: Name: MyAPI Description: My REST API EndpointConfiguration: Types: - REGIONAL
# リソース UsersResource: Type: AWS::ApiGateway::Resource Properties: RestApiId: !Ref RestApi PathPart: users ParentId: !GetAtt RestApi.RootResourceId
# GET /users GetUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: GET AuthorizationType: AWS_IAM Integration: Type: AWS_PROXY IntegrationHttpMethod: POST Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetUsersFunction.Arn}/invocations'
# POST /users PostUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: POST AuthorizationType: AWS_IAM Integration: Type: AWS_PROXY IntegrationHttpMethod: POST Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${CreateUserFunction.Arn}/invocations'
# デプロイメント Deployment: Type: AWS::ApiGateway::Deployment Properties: RestApiId: !Ref RestApi StageName: prod StageDescription: Production stageLambda統合
Section titled “Lambda統合”Resources: GetUsersFunction: Type: AWS::Lambda::Function Properties: FunctionName: GetUsers Runtime: python3.11 Handler: index.handler Code: ZipFile: | def handler(event, context): return { 'statusCode': 200, 'body': '{"users": []}' }
GetUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: GET AuthorizationType: NONE Integration: Type: AWS_PROXY IntegrationHttpMethod: POST Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetUsersFunction.Arn}/invocations'
# Lambda関数にAPI Gatewayの実行権限を付与 GetUsersPermission: Type: AWS::Lambda::Permission Properties: FunctionName: !Ref GetUsersFunction Action: lambda:InvokeFunction Principal: apigateway.amazonaws.com SourceArn: !Sub 'arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${RestApi}/*/GET/users'3. 認証・認可
Section titled “3. 認証・認可”API Key
Section titled “API Key”Resources: ApiKey: Type: AWS::ApiGateway::ApiKey Properties: Name: MyAPIKey Description: API Key for MyAPI Enabled: true
UsagePlan: Type: AWS::ApiGateway::UsagePlan Properties: UsagePlanName: MyUsagePlan ApiStages: - ApiId: !Ref RestApi Stage: prod Throttle: BurstLimit: 100 RateLimit: 50 Quota: Limit: 10000 Period: MONTH
UsagePlanKey: Type: AWS::ApiGateway::UsagePlanKey Properties: KeyId: !Ref ApiKey KeyType: API_KEY UsagePlanId: !Ref UsagePlanCognito認証
Section titled “Cognito認証”Resources: UserPool: Type: AWS::Cognito::UserPool Properties: UserPoolName: MyUserPool AutoVerifiedAttributes: - email
UserPoolClient: Type: AWS::Cognito::UserPoolClient Properties: UserPoolId: !Ref UserPool ClientName: MyUserPoolClient GenerateSecret: false
GetUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: GET AuthorizationType: COGNITO_USER_POOLS AuthorizerId: !Ref CognitoAuthorizer
CognitoAuthorizer: Type: AWS::ApiGateway::Authorizer Properties: Name: CognitoAuthorizer Type: COGNITO_USER_POOLS RestApiId: !Ref RestApi ProviderARNs: - !GetAtt UserPool.ArnResources: GetUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: GET AuthorizationType: AWS_IAM Integration: Type: AWS_PROXY IntegrationHttpMethod: POST Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetUsersFunction.Arn}/invocations'4. レート制限とクォータ
Section titled “4. レート制限とクォータ”レート制限の設定
Section titled “レート制限の設定”Resources: UsagePlan: Type: AWS::ApiGateway::UsagePlan Properties: UsagePlanName: MyUsagePlan ApiStages: - ApiId: !Ref RestApi Stage: prod Throttle: /users/GET: BurstLimit: 100 RateLimit: 50 Throttle: BurstLimit: 200 RateLimit: 100 Quota: Limit: 10000 Period: MONTH5. キャッシング
Section titled “5. キャッシング”API Gatewayキャッシング
Section titled “API Gatewayキャッシング”Resources: GetUsersMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: GET AuthorizationType: NONE MethodResponses: - StatusCode: 200 ResponseParameters: method.response.header.Cache-Control: true Integration: Type: AWS_PROXY IntegrationHttpMethod: POST Uri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetUsersFunction.Arn}/invocations' IntegrationResponses: - StatusCode: 200 ResponseParameters: method.response.header.Cache-Control: "'max-age=300'"
Deployment: Type: AWS::ApiGateway::Deployment Properties: RestApiId: !Ref RestApi StageName: prod CacheClusterEnabled: true CacheClusterSize: 0.56. CORS設定
Section titled “6. CORS設定”CORSの設定
Section titled “CORSの設定”Resources: OptionsMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: OPTIONS AuthorizationType: NONE Integration: Type: MOCK IntegrationResponses: - StatusCode: 200 ResponseParameters: method.response.header.Access-Control-Allow-Headers: "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token'" method.response.header.Access-Control-Allow-Methods: "'GET,POST,PUT,DELETE,OPTIONS'" method.response.header.Access-Control-Allow-Origin: "'https://example.com'" ResponseTemplates: application/json: '' MethodResponses: - StatusCode: 200 ResponseParameters: method.response.header.Access-Control-Allow-Headers: true method.response.header.Access-Control-Allow-Methods: true method.response.header.Access-Control-Allow-Origin: true7. WebSocket API
Section titled “7. WebSocket API”WebSocket APIの設定
Section titled “WebSocket APIの設定”Resources: WebSocketApi: Type: AWS::ApiGatewayV2::Api Properties: Name: MyWebSocketAPI ProtocolType: WEBSOCKET RouteSelectionExpression: '$request.body.action'
# $connect ルート ConnectRoute: Type: AWS::ApiGatewayV2::Route Properties: ApiId: !Ref WebSocketApi RouteKey: $connect Target: !Sub 'integrations/${ConnectIntegration}'
ConnectIntegration: Type: AWS::ApiGatewayV2::Integration Properties: ApiId: !Ref WebSocketApi IntegrationType: AWS_PROXY IntegrationUri: !Sub 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${ConnectFunction.Arn}/invocations'
# $disconnect ルート DisconnectRoute: Type: AWS::ApiGatewayV2::Route Properties: ApiId: !Ref WebSocketApi RouteKey: $disconnect Target: !Sub 'integrations/${DisconnectIntegration}'
# カスタムルート SendMessageRoute: Type: AWS::ApiGatewayV2::Route Properties: ApiId: !Ref WebSocketApi RouteKey: sendmessage Target: !Sub 'integrations/${SendMessageIntegration}'
# デプロイメント WebSocketDeployment: Type: AWS::ApiGatewayV2::Deployment Properties: ApiId: !Ref WebSocketApi
WebSocketStage: Type: AWS::ApiGatewayV2::Stage Properties: ApiId: !Ref WebSocketApi StageName: prod DeploymentId: !Ref WebSocketDeployment8. 実務でのベストプラクティス
Section titled “8. 実務でのベストプラクティス”パターン1: マイクロサービス統合
Section titled “パターン1: マイクロサービス統合”Resources: RestApi: Type: AWS::ApiGateway::RestApi Properties: Name: MicroservicesAPI
# ユーザーサービス UsersResource: Type: AWS::ApiGateway::Resource Properties: RestApiId: !Ref RestApi PathPart: users
# 注文サービス OrdersResource: Type: AWS::ApiGateway::Resource Properties: RestApiId: !Ref RestApi PathPart: ordersパターン2: バージョニング
Section titled “パターン2: バージョニング”Resources: RestApi: Type: AWS::ApiGateway::RestApi Properties: Name: MyAPI
# v1リソース V1Resource: Type: AWS::ApiGateway::Resource Properties: RestApiId: !Ref RestApi PathPart: v1
# v2リソース V2Resource: Type: AWS::ApiGateway::Resource Properties: RestApiId: !Ref RestApi PathPart: v29. よくある問題と解決策
Section titled “9. よくある問題と解決策”問題1: CORSエラー
Section titled “問題1: CORSエラー”原因:
- CORS設定が正しくない
- プリフライトリクエストが処理されていない
解決策:
# OPTIONSメソッドの追加Resources: OptionsMethod: Type: AWS::ApiGateway::Method Properties: RestApiId: !Ref RestApi ResourceId: !Ref UsersResource HttpMethod: OPTIONS AuthorizationType: NONE Integration: Type: MOCK問題2: タイムアウトエラー
Section titled “問題2: タイムアウトエラー”原因:
- Lambda関数の実行時間が長い
- 統合タイムアウトが短い
解決策:
Resources: GetUsersMethod: Type: AWS::ApiGateway::Method Properties: Integration: TimeoutInMillis: 29000 # 最大29秒これで、API Gatewayの基礎知識と実務での使い方を理解できるようになりました。