AWS Lambda Functions

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• Best Practices

Overview

AWS Lambda enables you to run code without provisioning or managing servers. Build serverless applications using event-driven triggers, pay only for compute time consumed, and scale automatically with workload.

When to Use

• API endpoints and webhooks
• Scheduled batch jobs and data processing
• Real-time file processing (S3 uploads)
• Event-driven workflows (SNS, SQS)
• Microservices and backend APIs
• Data transformations and ETL jobs
• IoT and sensor data processing
• WebSocket connections

Quick Start

Minimal working example:

# Create Lambda execution role
aws iam create-role \
  --role-name lambda-execution-role \
  --assume-role-policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Allow",
      "Principal": {"Service": "lambda.amazonaws.com"},
      "Action": "sts:AssumeRole"
    }]
  }'

# Attach basic execution policy
aws iam attach-role-policy \
  --role-name lambda-execution-role \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

# Create function from ZIP
zip function.zip index.js
aws lambda create-function \
  --function-name my-function \
  --runtime nodejs18.x \
  --role arn:aws:iam::ACCOUNT:role/lambda-execution-role \
  --handler index.handler \
  --zip-file fileb://function.zip \
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide	Contents
Basic Lambda Function with AWS CLI	Basic Lambda Function with AWS CLI
Lambda Function with Node.js	Lambda Function with Node.js
Terraform Lambda Deployment	Terraform Lambda Deployment
Lambda with SAM (Serverless Application Model)	Lambda with SAM (Serverless Application Model)
Lambda Layers for Code Sharing	Lambda Layers for Code Sharing

Best Practices

✅ DO

• Use environment variables for configuration
• Implement proper error handling and logging
• Optimize package size and dependencies
• Set appropriate timeout and memory
• Use Lambda Layers for shared code
• Implement concurrency limits
• Enable X-Ray tracing for debugging
• Use reserved concurrency for critical functions

❌ DON'T

• Store sensitive data in code
• Create long-running operations (>15 min)
• Ignore cold start optimization
• Forget to handle concurrent executions
• Ignore CloudWatch metrics
• Use too much memory unnecessarily