AWS Lambda

# Lambda 핸들러 함수 예제 (Python)
import json
import boto3
import logging
from datetime import datetime

logger = logging.getLogger()
logger.setLevel(logging.INFO)

# Lambda 컨테이너 재사용 시 연결 유지 (콜드 스타트 최적화)
dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('users')

def lambda_handler(event, context):
    """
    API Gateway에서 호출되는 Lambda 핸들러
    event: API Gateway 이벤트 객체
    context: Lambda 실행 컨텍스트 (요청 ID, 남은 시간 등)
    """
    logger.info(f"Request ID: {context.aws_request_id}")
    logger.info(f"Remaining time: {context.get_remaining_time_in_millis()}ms")

    try:
        # API Gateway 이벤트 파싱
        body = json.loads(event.get('body', '{}'))
        user_id = event['pathParameters']['userId']

        # DynamoDB 조회
        response = table.get_item(Key={'userId': user_id})

        if 'Item' not in response:
            return {
                'statusCode': 404,
                'headers': {'Content-Type': 'application/json'},
                'body': json.dumps({'error': 'User not found'})
            }

        return {
            'statusCode': 200,
            'headers': {
                'Content-Type': 'application/json',
                'Access-Control-Allow-Origin': '*'
            },
            'body': json.dumps(response['Item'], default=str)
        }

    except Exception as e:
        logger.error(f"Error: {str(e)}")
        return {
            'statusCode': 500,
            'body': json.dumps({'error': 'Internal server error'})
        }


# S3 이벤트 트리거 예제
def s3_handler(event, context):
    """S3 파일 업로드 시 트리거되는 핸들러"""
    s3_client = boto3.client('s3')

    for record in event['Records']:
        bucket = record['s3']['bucket']['name']
        key = record['s3']['object']['key']

        logger.info(f"Processing: s3://{bucket}/{key}")

        # 파일 처리 로직...
        # 예: 이미지 리사이즈, 데이터 변환 등

    return {'processed': len(event['Records'])}

// Lambda 핸들러 함수 예제 (Node.js)
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, GetCommand } from "@aws-sdk/lib-dynamodb";

// 글로벌 스코프에서 클라이언트 초기화 (연결 재사용)
const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const handler = async (event, context) => {
    console.log('Request ID:', context.awsRequestId);
    console.log('Event:', JSON.stringify(event, null, 2));

    try {
        const { userId } = event.pathParameters;

        // DynamoDB 조회
        const command = new GetCommand({
            TableName: process.env.TABLE_NAME,
            Key: { userId }
        });

        const response = await docClient.send(command);

        if (!response.Item) {
            return {
                statusCode: 404,
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ error: 'User not found' })
            };
        }

        return {
            statusCode: 200,
            headers: {
                'Content-Type': 'application/json',
                'Access-Control-Allow-Origin': '*'
            },
            body: JSON.stringify(response.Item)
        };

    } catch (error) {
        console.error('Error:', error);
        return {
            statusCode: 500,
            body: JSON.stringify({ error: 'Internal server error' })
        };
    }
};

// SQS 이벤트 처리 예제
export const sqsHandler = async (event) => {
    const batchItemFailures = [];

    for (const record of event.Records) {
        try {
            const body = JSON.parse(record.body);
            console.log('Processing message:', body);

            // 메시지 처리 로직...
            await processMessage(body);

        } catch (error) {
            console.error(`Failed to process ${record.messageId}:`, error);
            // 실패한 메시지만 다시 큐로 (Partial Batch Response)
            batchItemFailures.push({ itemIdentifier: record.messageId });
        }
    }

    return { batchItemFailures };
};

# SAM (Serverless Application Model) 템플릿
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Lambda API 서비스

Globals:
  Function:
    Timeout: 30
    MemorySize: 256
    Runtime: python3.11
    Architectures:
      - arm64  # Graviton2, 최대 34% 가성비 향상
    Environment:
      Variables:
        TABLE_NAME: !Ref UsersTable
        LOG_LEVEL: INFO

Resources:
  # API Gateway
  ApiGateway:
    Type: AWS::Serverless::Api
    Properties:
      StageName: prod
      Cors:
        AllowOrigin: "'*'"
        AllowMethods: "'GET,POST,PUT,DELETE'"
        AllowHeaders: "'Content-Type,Authorization'"

  # Lambda 함수
  GetUserFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: get-user
      CodeUri: src/
      Handler: handlers.get_user
      Description: 사용자 정보 조회
      Events:
        GetUser:
          Type: Api
          Properties:
            RestApiId: !Ref ApiGateway
            Path: /users/{userId}
            Method: get
      Policies:
        - DynamoDBReadPolicy:
            TableName: !Ref UsersTable

  # S3 트리거 Lambda
  ProcessImageFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: process-image
      CodeUri: src/
      Handler: handlers.process_image
      MemorySize: 1024
      Timeout: 60
      Events:
        S3Upload:
          Type: S3
          Properties:
            Bucket: !Ref ImageBucket
            Events: s3:ObjectCreated:*
            Filter:
              S3Key:
                Rules:
                  - Name: suffix
                    Value: .jpg
      Policies:
        - S3CrudPolicy:
            BucketName: !Ref ImageBucket

  # 스케줄 Lambda (Cron)
  DailyReportFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: daily-report
      CodeUri: src/
      Handler: handlers.daily_report
      Events:
        ScheduleEvent:
          Type: Schedule
          Properties:
            Schedule: cron(0 9 * * ? *)  # 매일 오전 9시 (UTC)
            Description: 일일 리포트 생성

  # DynamoDB 테이블
  UsersTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: users
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: userId
          AttributeType: S
      KeySchema:
        - AttributeName: userId
          KeyType: HASH

Outputs:
  ApiEndpoint:
    Description: API Gateway endpoint URL
    Value: !Sub "https://${ApiGateway}.execute-api.${AWS::Region}.amazonaws.com/prod/"