AWS Lambda Functions

Table of Contents

• [Overview](#overview)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Reference Guides](#reference-guides)
• [Best Practices](#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:

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