AWS Lambda Cheat Sheet for Beginners.

Introduction.

AWS Lambda is one of the most powerful services offered by Amazon Web Services. It allows developers to run code without managing or provisioning servers. This concept is known as serverless computing. For beginners, serverless can sound confusing at first. However, AWS Lambda simplifies cloud development significantly. You only focus on writing your application logic.

AWS takes care of scaling, availability, and infrastructure. This makes Lambda ideal for newcomers to cloud computing. One of the biggest advantages of AWS Lambda is its ease of use. You don’t need deep infrastructure knowledge to get started. Lambda functions are event-driven by nature. They run automatically when something happens in AWS. For example, uploading a file or calling an API. This event-based execution makes applications more efficient.

AWS Lambda is also cost-effective for beginners. You pay only when your code runs. There is no cost when your function is idle. The free tier offers generous usage limits every month. This allows beginners to experiment without worrying about billing. Lambda supports multiple programming languages. Popular options include Python and Node.js. This flexibility makes it accessible to many developers. Lambda integrates seamlessly with other AWS services. Services like S3, DynamoDB, and API Gateway work well with Lambda. Together, they enable fully serverless applications.

Beginners can build real-world projects quickly. There is no need to manage servers or operating systems.
Deployment is simple and fast. Monitoring is handled through Amazon CloudWatch. Logs and metrics are available by default. This helps beginners debug their applications easily. AWS Lambda automatically scales with demand. It can handle one request or thousands at the same time. You do not need to configure scaling rules.
This makes applications more reliable and responsive. Lambda encourages writing small and focused functions.

This improves code quality and maintainability. It also aligns with modern microservices architecture. Learning AWS Lambda builds strong cloud fundamentals. It introduces key concepts like events and permissions. Understanding Lambda helps with other AWS services. This cheat sheet is designed for absolute beginners.
It focuses on clarity and quick understanding. Complex details are simplified for easy learning. You will find essential concepts in one place. The goal is to help you get started faster. By the end, AWS Lambda will feel less intimidating. This guide serves as your first step into serverless computing.

What Is AWS Lambda?

AWS Lambda is a serverless compute service that runs your code in response to events and automatically manages the underlying infrastructure. You upload your code, define when it should run, and AWS takes care of scaling, availability, and execution.

In simple terms:
You write code. AWS runs it. You don’t manage servers.

Key AWS Lambda Concepts (Quick Reference)

Function

• A Lambda function is your code.
• Written in languages like Python, Node.js, Java, Go, etc.
• Executes when triggered by an event.

Trigger

• An event that starts a Lambda function.
• Common triggers:
  • API Gateway (HTTP requests)
  • S3 (file uploads)
  • DynamoDB (table changes)
  • EventBridge (scheduled jobs)
  • SQS/SNS (messaging)

Execution Role (IAM Role)

• Grants Lambda permission to access other AWS services.
• Example: Read from S3 or write logs to CloudWatch.

Event

• The input data sent to your function.
• Format depends on the trigger source.

AWS Lambda Free Tier (Beginner Must-Know)

• 1 million requests per month
• 400,000 GB-seconds of compute time per month
• Free tier resets every month
• Ideal for learning, testing, and small projects

Supported Runtimes

• Python
• Node.js
• Java
• Go
• .NET
• Ruby
• Custom runtimes (advanced)

Beginner Tip: Python and Node.js are the easiest to start with.

AWS Lambda Limits (Cheat Sheet)

How AWS Lambda Pricing Works

You pay for:

1. Number of requests
2. Execution time (GB-seconds)

💡 You are charged only when your code runs.

Common Use Cases

• Backend APIs
• File processing (images, PDFs, videos)
• Scheduled tasks (cron jobs)
• Data transformation
• Real-time notifications
• Microservices

Basic Lambda Function Example (Python)

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

Monitoring & Logging

• Logs automatically go to Amazon CloudWatch
• Metrics available:
  • Invocations
  • Duration
  • Errors
  • Throttles

Best Practices for Beginners

• Keep functions small and focused
• Use least-privilege IAM roles
• Optimize memory to reduce cost
• Monitor usage to stay within free tier
• Avoid hardcoding secrets (use environment variables)

Common Beginner Mistakes

• Forgetting to add permissions
• Triggering functions too frequently
• Over-allocating memory
• Ignoring CloudWatch logs
• Assuming Lambda is always free

AWS Lambda vs EC2 (Quick Comparison)

When Should You Use AWS Lambda?

✅ Event-driven workloads
✅ Low to medium traffic apps
✅ Microservices
✅ Automation tasks

❌ Long-running processes
❌ Applications needing persistent connections

Final Thoughts

AWS Lambda is one of the easiest ways to get started with cloud computing and serverless architecture. Its generous free tier, automatic scaling, and simple pricing make it ideal for beginners. With this cheat sheet, you now have a quick reference to understand Lambda’s core concepts, limits, pricing, and best practices.

For more information about AWS Lambda, you can refer to Jeevi’s page.

This tutorial is just the beginning learn AWS hands-on in our complete course. Upgrade your skills with AWS.