AWS — Lambda

What is Lambda?

Serverless compute service that runs code without provisioning servers.

Create function

aws lambda create-function \
  --function-name my-function \
  --runtime python3.9 \
  --handler lambda_function.lambda_handler \
  --role arn:aws:iam::123456789:role/lambda-role \
  --zip-file fileb://function.zip

Python handler

import json

def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }

Invoke

aws lambda invoke \
  --function-name my-function \
  --payload '{"key": "value"}' \
  response.json

Triggers

• API Gateway: HTTP requests
• S3: Object events
• DynamoDB: Stream events
• SQS: Message processing
• EventBridge: Scheduled events

Environment variables

aws lambda update-function-configuration \
  --function-name my-function \
  --environment "Variables={DB_HOST=mydb.xxx,API_KEY=abc123}"

Layers

aws lambda publish-layer-version \
  --layer-name my-layer \
  --zip-file fileb://layer.zip

aws lambda update-function-configuration \
  --function-name my-function \
  --layers arn:aws:lambda:us-east-1:123456789:layer:my-layer:1

Concurrency

# Reserved concurrency
aws lambda put-function-concurrency \
  --function-name my-function \
  --reserved-concurrent-executions 100

Best practices

1. Keep functions small
2. Use environment variables
3. Handle errors gracefully
4. Monitor with CloudWatch

Mini Practice

1. Create a Lambda function
2. Test with sample event
3. Add an S3 trigger
4. Monitor with CloudWatch

Up Next

Continue with VPC - Virtual Private Cloud.