Learn AWS-LAMBDA with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Simple AWS Lambda Function (Python)

# aws_lambda/demo/lambda_function.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'body': 'Hello, Lambda!'
    }

A simple AWS Lambda function in Python that returns 'Hello, Lambda!' when invoked.

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AWS Lambda Function with Query Parameters

# aws_lambda/demo/query.py
def lambda_handler(event, context):
    name = event.get('queryStringParameters', {}).get('name', 'Guest')
    return {
        'statusCode': 200,
        'body': f'Hello, {name}!'
    }

Lambda reading query parameters from API Gateway and responding.

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AWS Lambda Function with JSON Response

# aws_lambda/demo/json.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'headers': {'Content-Type': 'application/json'},
        'body': '{"message": "Hello JSON!"}'
    }

Lambda returning JSON data.

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AWS Lambda Function Handling POST Requests

# aws_lambda/demo/post.py
def lambda_handler(event, context):
    if event.get('httpMethod') == 'POST':
        body = event.get('body')
        return {
        'statusCode': 200,
        'body': f'Received: {body}'
        }
    return {
        'statusCode': 405,
        'body': 'Method Not Allowed'
    }

Lambda processing POST request body from API Gateway.

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AWS Lambda Function Using Environment Variables

# aws_lambda/demo/env.py
import os
def lambda_handler(event, context):
    api_key = os.environ.get('MY_API_KEY', 'NotSet')
    return {
        'statusCode': 200,
        'body': f'API Key length: {len(api_key)}'
    }

Lambda accessing environment variables.

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AWS Lambda Function Redirect

# aws_lambda/demo/redirect.py
def lambda_handler(event, context):
    return {
        'statusCode': 302,
        'headers': {'Location': 'https://example.com'},
        'body': ''
    }

Lambda returning a redirect response.

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AWS Lambda Function with Custom Headers

# aws_lambda/demo/headers.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'headers': {'X-Custom-Header': 'LambdaExample'},
        'body': 'Custom headers added'
    }

Lambda adding custom headers in response.

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AWS Lambda Function Fetching External API

# aws_lambda/demo/fetch.py
import requests
def lambda_handler(event, context):
    response = requests.get('https://api.github.com')
    return {
        'statusCode': 200,
        'body': response.text
    }

Lambda fetching data from an external API and returning it.

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AWS Lambda Function Returning HTML

# aws_lambda/demo/html.py
def lambda_handler(event, context):
    html = '<!DOCTYPE html><html><body><h1>Hello HTML!</h1></body></html>'
    return {
        'statusCode': 200,
        'headers': {'Content-Type': 'text/html'},
        'body': html
    }

Lambda responding with a simple HTML page.

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AWS Lambda Function Conditional Response

# aws_lambda/demo/method.py
def lambda_handler(event, context):
    method = event.get('httpMethod')
    if method == 'POST':
        return {'statusCode': 200, 'body': 'You sent a POST request'}
    return {'statusCode': 200, 'body': 'You sent a GET request'}

Lambda responding differently based on HTTP method.

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Code Sample Descriptions

Simple AWS Lambda Function (Python)

# aws_lambda/demo/lambda_function.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'body': 'Hello, Lambda!'
    }

A simple AWS Lambda function in Python that returns 'Hello, Lambda!' when invoked.

Let’s Try →

AWS Lambda Function with Query Parameters

# aws_lambda/demo/query.py
def lambda_handler(event, context):
    name = event.get('queryStringParameters', {}).get('name', 'Guest')
    return {
        'statusCode': 200,
        'body': f'Hello, {name}!'
    }

Lambda reading query parameters from API Gateway and responding.

Let’s Try →

AWS Lambda Function with JSON Response

# aws_lambda/demo/json.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'headers': {'Content-Type': 'application/json'},
        'body': '{"message": "Hello JSON!"}'
    }

Lambda returning JSON data.

Let’s Try →

AWS Lambda Function Handling POST Requests

# aws_lambda/demo/post.py
def lambda_handler(event, context):
    if event.get('httpMethod') == 'POST':
        body = event.get('body')
        return {
        'statusCode': 200,
        'body': f'Received: {body}'
        }
    return {
        'statusCode': 405,
        'body': 'Method Not Allowed'
    }

Lambda processing POST request body from API Gateway.

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AWS Lambda Function Using Environment Variables

# aws_lambda/demo/env.py
import os
def lambda_handler(event, context):
    api_key = os.environ.get('MY_API_KEY', 'NotSet')
    return {
        'statusCode': 200,
        'body': f'API Key length: {len(api_key)}'
    }

Lambda accessing environment variables.

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AWS Lambda Function Redirect

# aws_lambda/demo/redirect.py
def lambda_handler(event, context):
    return {
        'statusCode': 302,
        'headers': {'Location': 'https://example.com'},
        'body': ''
    }

Lambda returning a redirect response.

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AWS Lambda Function with Custom Headers

# aws_lambda/demo/headers.py
def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'headers': {'X-Custom-Header': 'LambdaExample'},
        'body': 'Custom headers added'
    }

Lambda adding custom headers in response.

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AWS Lambda Function Fetching External API

# aws_lambda/demo/fetch.py
import requests
def lambda_handler(event, context):
    response = requests.get('https://api.github.com')
    return {
        'statusCode': 200,
        'body': response.text
    }

Lambda fetching data from an external API and returning it.

Let’s Try →

AWS Lambda Function Returning HTML

# aws_lambda/demo/html.py
def lambda_handler(event, context):
    html = '<!DOCTYPE html><html><body><h1>Hello HTML!</h1></body></html>'
    return {
        'statusCode': 200,
        'headers': {'Content-Type': 'text/html'},
        'body': html
    }

Lambda responding with a simple HTML page.

Let’s Try →

AWS Lambda Function Conditional Response

# aws_lambda/demo/method.py
def lambda_handler(event, context):
    method = event.get('httpMethod')
    if method == 'POST':
        return {'statusCode': 200, 'body': 'You sent a POST request'}
    return {'statusCode': 200, 'body': 'You sent a GET request'}

Lambda responding differently based on HTTP method.

Let’s Try →