---

name: aws-skills description: AWS development with CDK best practices, serverless patterns, cost optimization, and event-driven architecture. Use when deploying to AWS, writing Lambda functions, configuring API Gateway, working with DynamoDB, S3, or any AWS service.

AWS Development Skills

AWS CDK Best Practices

Project Structure

infrastructure/
├── bin/
│   └── app.ts              # CDK app entry point
├── lib/
│   ├── stacks/
│   │   ├── api-stack.ts
│   │   ├── database-stack.ts
│   │   └── storage-stack.ts
│   ├── constructs/
│   │   ├── lambda-function.ts
│   │   └── api-gateway.ts
│   └── config/
│       └── environment.ts
├── lambda/
│   └── handlers/
├── cdk.json
└── package.json

Stack Definition

import * as cdk from 'aws-cdk-lib';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as apigateway from 'aws-cdk-lib/aws-apigateway';
import { Construct } from 'constructs';

interface ApiStackProps extends cdk.StackProps {
  environment: string;
  domainName?: string;
}

export class ApiStack extends cdk.Stack {
  public readonly api: apigateway.RestApi;

  constructor(scope: Construct, id: string, props: ApiStackProps) {
    super(scope, id, props);

    const handler = new lambda.Function(this, 'ApiHandler', {
      runtime: lambda.Runtime.NODEJS_18_X,
      handler: 'index.handler',
      code: lambda.Code.fromAsset('lambda/handlers'),
      environment: { NODE_ENV: props.environment },
      memorySize: 256,
      timeout: cdk.Duration.seconds(30),
    });

    this.api = new apigateway.RestApi(this, 'Api', {
      restApiName: `${props.environment}-api`,
      deployOptions: {
        stageName: props.environment,
        throttlingRateLimit: 1000,
        throttlingBurstLimit: 500,
      },
    });

    const integration = new apigateway.LambdaIntegration(handler);
    this.api.root.addMethod('GET', integration);
  }
}

Serverless Patterns

Lambda Best Practices

import { APIGatewayProxyHandler } from 'aws-lambda';

// Initialize outside handler for connection reuse
const dynamodb = new DynamoDB.DocumentClient();

export const handler: APIGatewayProxyHandler = async (event) => {
  try {
    const body = JSON.parse(event.body || '{}');
    const result = await processRequest(body);
    return response(200, result);
  } catch (error) {
    console.error('Error:', error);
    return response(500, { error: 'Internal server error' });
  }
};

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

DynamoDB Single-Table Design

const table = new dynamodb.Table(this, 'Table', {
  partitionKey: { name: 'PK', type: dynamodb.AttributeType.STRING },
  sortKey: { name: 'SK', type: dynamodb.AttributeType.STRING },
  billingMode: dynamodb.BillingMode.PAY_PER_REQUEST,
});

// Access patterns
// User by ID:      PK=USER#123, SK=PROFILE
// User's orders:   PK=USER#123, SK=ORDER#timestamp
// Order by ID:     GSI1PK=ORDER#456, GSI1SK=ORDER#456

Event-Driven with EventBridge

const rule = new events.Rule(this, 'OrderCreatedRule', {
  eventPattern: {
    source: ['orders'],
    detailType: ['OrderCreated'],
  },
});

rule.addTarget(new targets.LambdaFunction(processOrderHandler));
rule.addTarget(new targets.SqsQueue(notificationQueue));

SQS + Lambda Pattern

const dlq = new sqs.Queue(this, 'DeadLetterQueue');

const queue = new sqs.Queue(this, 'ProcessingQueue', {
  visibilityTimeout: cdk.Duration.seconds(300),
  deadLetterQueue: { queue: dlq, maxReceiveCount: 3 },
});

processor.addEventSource(new SqsEventSource(queue, {
  batchSize: 10,
  maxBatchingWindow: cdk.Duration.seconds(5),
}));

Cost Optimization

Lambda Optimization

const handler = new lambda.Function(this, 'Handler', {
  memorySize: 256,
  timeout: cdk.Duration.seconds(10),
  architecture: lambda.Architecture.ARM_64, // Cost savings
});

S3 Lifecycle Rules

const bucket = new s3.Bucket(this, 'Bucket', {
  lifecycleRules: [{
    transitions: [
      { storageClass: s3.StorageClass.INFREQUENT_ACCESS, transitionAfter: cdk.Duration.days(30) },
      { storageClass: s3.StorageClass.GLACIER, transitionAfter: cdk.Duration.days(90) },
    ],
    expiration: cdk.Duration.days(365),
  }],
});

Security Best Practices

IAM Least Privilege

// Grant methods (preferred)
table.grantReadWriteData(handler);
bucket.grantRead(handler);

Secrets Management

const secret = secretsmanager.Secret.fromSecretNameV2(this, 'DbSecret', 'prod/db/credentials');
secret.grantRead(handler);

Monitoring

CloudWatch Alarms

new cloudwatch.Alarm(this, 'LambdaErrors', {
  metric: handler.metricErrors(),
  threshold: 1,
  evaluationPeriods: 1,
});

X-Ray Tracing

const handler = new lambda.Function(this, 'Handler', {
  tracing: lambda.Tracing.ACTIVE,
});