aws-lambda

AWS Lambda

Build serverless applications with AWS Lambda, covering function creation, event sources, layers, SAM templates, and cold start optimization.

When to Use This Skill

• Building event-driven applications triggered by API Gateway, S3, SQS, or EventBridge
• Running scheduled tasks (cron) without managing servers
• Processing data streams from Kinesis or DynamoDB
• Building lightweight APIs with API Gateway or function URLs
• Implementing webhooks, Slack bots, or automation scripts
• Reducing compute costs for intermittent or bursty workloads

Prerequisites

• AWS CLI v2 installed and configured
• IAM permissions: lambda:*, iam:PassRole, logs:*, apigateway:*, s3:*
• Python 3.11+, Node.js 20+, or another supported runtime installed locally
• (Optional) AWS SAM CLI for local development and deployment

Create and Deploy a Function

# Create a deployment package
cd my-function
zip -r function.zip app.py

# Create the Lambda function
aws lambda create-function \
  --function-name my-api-handler \
  --runtime python3.12 \
  --handler app.handler \
  --role arn:aws:iam::123456789012:role/LambdaExecRole \
  --zip-file fileb://function.zip \
  --memory-size 256 \
  --timeout 30 \
  --environment 'Variables={STAGE=production,LOG_LEVEL=INFO}' \
  --architectures arm64 \
  --tracing-config Mode=Active \
  --tags '{"Team":"backend","Environment":"production"}'

# Update function code
aws lambda update-function-code \
  --function-name my-api-handler \
  --zip-file fileb://function.zip

# Update function configuration
aws lambda update-function-configuration \
  --function-name my-api-handler \
  --memory-size 512 \
  --timeout 60 \
  --environment 'Variables={STAGE=production,LOG_LEVEL=WARNING}'

# Publish a version (immutable snapshot)
aws lambda publish-version \
  --function-name my-api-handler \
  --description "v1.2.0 - added rate limiting"

# Create an alias pointing to the version
aws lambda create-alias \
  --function-name my-api-handler \
  --name live \
  --function-version 3

# Weighted alias for canary deployments (90% v3, 10% v4)
aws lambda update-alias \
  --function-name my-api-handler \
  --name live \
  --function-version 4 \
  --routing-config '{"AdditionalVersionWeights":{"3":0.9}}'