Chapter 1: AWS Lambda Basic Concepts

Learning Objectives

• Understand what AWS Lambda is and its core concepts
• Master the working principle and execution model of Lambda
• Understand the advantages and use cases of Lambda
• Understand the concept of Serverless architecture

Knowledge Points

What is AWS Lambda

AWS Lambda is a Function as a Service (FaaS) platform provided by Amazon Web Services that allows developers to run code without managing servers. Lambda automatically handles the allocation, scaling, and management of computing resources.

Core Concepts

• Function: The basic execution unit of Lambda, containing code and configuration information
• Event: The data that triggers the execution of a Lambda function
• Runtime: The execution environment for the function code
• Handler: The entry point of the function

Serverless Architecture Concept Diagram

How Lambda Works

Example Code

Simple Python Lambda Function

import json

def lambda_handler(event, context):
    """
    The basic structure of a Lambda function
    
    Args:
        event: A dictionary containing information about the triggering event
        context: A runtime information object
    
    Returns:
        dict: A dictionary containing the status code and response body
    """
    
    # Process the input event
    name = event.get('name', 'World')
    
    # Execute business logic
    message = f"Hello, {name}!"
    
    # Return the response
    return {
        'statusCode': 200,
        'headers': {
            'Content-Type': 'application/json'
        },
        'body': json.dumps({
            'message': message,
            'requestId': context.aws_request_id
        })
    }

Event Object Structure Example

# Example of an event triggered by API Gateway
api_gateway_event = {
    "httpMethod": "GET",
    "path": "/hello",
    "queryStringParameters": {
        "name": "Alice"
    },
    "headers": {
        "Content-Type": "application/json"
    },
    "body": None,
    "requestContext": {
        "requestId": "12345",
        "stage": "prod"
    }
}

# Example of an S3 event trigger
s3_event = {
    "Records": [
        {
            "eventSource": "aws:s3",
            "eventName": "ObjectCreated:Put",
            "s3": {
                "bucket": {
                    "name": "my-bucket"
                },
                "object": {
                    "key": "uploads/image.jpg"
                }
            }
        }
    ]
}

Advantages and Features of Lambda

Key Advantages of Lambda

• No Server Management: No need to manage the underlying infrastructure
• Automatic Scaling: Automatically scales up and down based on request volume
• Pay-per-use: Only pay for the code execution time
• High Availability: AWS automatically handles fault recovery
• Rapid Deployment: Deployment and updates in seconds

Important Notes

• Execution Time Limit: Up to 15 minutes
• Memory Limit: 128MB to 10,240MB
• Cold Start Latency: There may be a delay on the first call
• Stateless: Functions should be designed to be stateless

Use Case Comparison

Scenario Type	Applicability	Example
Data Processing	✅ Very suitable	Image processing, log analysis, ETL operations
Web API	✅ Suitable	REST API, microservices backend
Real-time Processing	✅ Suitable	Stream data processing, real-time analysis
Scheduled Tasks	✅ Suitable	Data backup, report generation
Long-running Tasks	❌ Not suitable	Big data batch processing, machine learning training
Stateful Applications	❌ Not suitable	Database services, caching services

Comparison with Traditional Servers

Key Takeaways

Lambda abstracts away infrastructure management, allowing developers to focus on implementing business logic, and is an important part of modern cloud-native application development.