lambda

AWS Lambda

AWS Lambda runs code without provisioning servers. You pay only for compute time consumed. Lambda automatically scales from a few requests per day to thousands per second.

Table of Contents

• Core Concepts
• Common Patterns
• CLI Reference
• Best Practices
• Troubleshooting
• References

Core Concepts

Function

Your code packaged with configuration. Includes runtime, handler, memory, timeout, and IAM role.

Invocation Types

Type	Description	Use Case
Synchronous	Caller waits for response	API Gateway, direct invoke
Asynchronous	Fire and forget	S3, SNS, EventBridge
Poll-based	Lambda polls source	SQS, Kinesis, DynamoDB Streams

Execution Environment

Lambda creates execution environments to run your function. Components:

• Cold start: New environment initialization
• Warm start: Reusing existing environment
• Handler: Entry point function
• Context: Runtime information

Layers

Reusable packages of libraries, dependencies, or custom runtimes (up to 5 per function).

Common Patterns

Create a Python Function

AWS CLI:

# Create deployment package
zip function.zip lambda_function.py

# Create function
aws lambda create-function \
  --function-name MyFunction \
  --runtime python3.12 \
  --role arn:aws:iam::123456789012:role/lambda-role \
  --handler lambda_function.handler \
  --zip-file fileb://function.zip \
  --timeout 30 \
  --memory-size 256

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

boto3:

import boto3
import zipfile
import io

lambda_client = boto3.client('lambda')

# Create zip in memory
zip_buffer = io.BytesIO()
with zipfile.ZipFile(zip_buffer, 'w') as zf:
    zf.writestr('lambda_function.py', '''
def handler(event, context):
    return {"statusCode": 200, "body": "Hello"}
''')
zip_buffer.seek(0)

# Create function
lambda_client.create_function(
    FunctionName='MyFunction',
    Runtime='python3.12',
    Role='arn:aws:iam::123456789012:role/lambda-role',
    Handler='lambda_function.handler',
    Code={'ZipFile': zip_buffer.read()},
    Timeout=30,
    MemorySize=256
)