How to Develop Serverless Applications with AWS Lambda & Amazon API Gateway

Serverless applications have become increasingly popular due to their scalability, flexibility, and cost-effectiveness. AWS Lambda, in conjunction with Amazon API Gateway, offers a powerful platform to build and deploy serverless applications.

Let’s dive into how you can develop serverless applications using these services.

What is AWS Lambda?

AWS Lambda is an event-driven, serverless computing platform provided by Amazon Web Services (AWS) that runs code in response to events and automatically manages the computing resources required by that code. 

The concept of “serverless” computing refers to not needing to maintain your own servers to run these functions. AWS Lambda is a fully managed service that takes care of all the infrastructure for you.

And so “serverless” doesn’t mean that there are no servers involved: it just means that the servers, the operating systems, the network layer and the rest of the infrastructure have already been taken care of, so that you can focus on writing application code.

How does AWS Lambda work?

Every Lambda function has a container in which it operates. Lambda creates a function, bundles it into a new container, and runs that container on an AWS-managed multi-tenant cluster of servers.

The required RAM and CPU power are assigned to each function’s container before the functions begin to operate. The RAM allotted at the beginning is multiplied by the duration of the function’s execution once it has been completed.

After that, the clients are billed according to the memory that was allotted and the length of time the function took to finish running.

Benefits of using AWS Lambda

AWS Lambda offers several benefits that can make your development process more efficient and cost-effective. Here are some of the key advantages:

• Focus on Code, Not Servers: No more wrestling with server setup and maintenance. Lambda frees you to focus on what matters – building great applications.
• Pay-Per-Use: Only pay for the compute time you actually use. This makes Lambda super cost-effective, especially for applications with bursty workloads.
• Automatic Scaling: Lambda scales your code up or down automatically based on demand. No more worrying about over-provisioning or under-provisioning resources.
• Event-Driven: Lambda triggers your code in response to events from other AWS services, like S3 or DynamoDB. This makes it perfect for building microservices and serverless architectures.

What is Amazon API Gateway?

Amazon API Gateway is a managed service that allows developers to define the HTTP endpoints of a REST API or a WebSocket API and connect those endpoints with the backend business logic.

It handles all the tasks involved in accepting and processing up to hundreds of thousands of concurrent API calls, including traffic management, authorization, access control, monitoring, and API version management.

API Gateway creates RESTful APIs that:

• Are HTTP-based.
• Enable stateless client-server communication.
• Implement standard HTTP methods such as GET, POST, PUT, PATCH, and DELETE.

The architecture of API Gateway

An API Gateway acts as a single entry point for clients trying to access a system’s backend services. It sits in front of the backend services and routes incoming requests to the appropriate service based on predefined rules.

The following diagram shows API Gateway architecture.

Differences Between AWS Lambda and API Gateway

The primary difference lies in their roles:

• AWS Lambda is responsible for executing your backend code in response to events such as HTTP requests, modifications to objects in Amazon S3, or updates in a DynamoDB table.
• Amazon API Gateway is a layer that provides the API interface and connects client requests to back-end services, which can be Lambda functions.

Building a Serverless Application with Lambda and API Gateway Step-by-Step

1. Plan Your Application
   Before you start, identify the functionality of your application, the API endpoints you will need, and the corresponding Lambda functions.
2. Create Your Lambda Functions
   • Go to the AWS Management Console and select AWS Lambda.
   • Click on “Create function” and select “Author from scratch”.
   • Define a function name, choose a runtime (e.g., Node.js, Python), and select the appropriate execution role.
   • Write the code for your handler function. This handler will process the incoming event (such as a web request) and return a response.
3. Set Up API Gateway
   • Navigate to Amazon API Gateway in the AWS Console.
   • Create a new API or use an existing one.
   • Define new resources (paths) and methods (HTTP verbs) that correspond to your application’s functionality.
4.  Connect API Gateway to Lambda
   • In the API Gateway console, create a new method for a resource, for instance, a GET method for the /users resource.
   • Set the integration type to Lambda Function and select the respective Lambda function you created in the earlier step.
   • Deploy your API to a new or existing stage.
5. Test Your Serverless Application
   • After deploying, test the API endpoint using tools like curl or Postman.
   • Ensure that the API Gateway successfully triggers your Lambda function and that the end-to-end process works as expected.
6.  Monitor and Debug
   • Use AWS CloudWatch to monitor the logs of both your API Gateway requests and your Lambda function invocations.
   • Set up alarms for any unexpected behavior or threshold breaches.
7.  Iterate and Optimize
   Based on monitoring and logs, make any necessary changes to optimize the performance and cost of your serverless application.

Popular AWS Lambda Frameworks

There are several popular frameworks that can help you develop and deploy serverless applications on AWS Lambda. Here are a few of the most commonly used ones

• AWS SAM (Serverless Application Model):  This is the official AWS framework and a solid alternative for individuals looking for a stable and well-supported solution. SAM makes it simple to handle infrastructure as code (IaC) by defining your serverless application using CloudFormation templates.
  
• Zappa: Python coders are very fond of this framework. Deploying current Flask or Django web applications to Lambda and API Gateway is made easier by it.
  
• Serverless Framework: While not exclusive to AWS, Serverless Framework is a popular option that supports multiple cloud providers, including AWS Lambda. It offers a wide range of features for developing, testing, and deploying serverless applications.
  
• AWS Chalice: This is an additional AWS-specific framework meant for Python serverless application development. For Python developers, Chalice offers a familiar vocabulary for constructing Lambda functions and APIs, making the transition to serverless development simple.
  
• Claudia.js: The main focus of this framework is AWS Lambda JavaScript programming. It provides functionality for local development and testing and expedites the deployment process.

Real-World Examples of AWS Lambda

AWS Lambda’s serverless architecture makes it a powerful tool for a variety of tasks. Here are some real-world examples of how companies are using AWS Lambda

• Data Processing: Processing data streams is a useful use case for lambda functions. To handle customer order data in real-time and issue order confirmations or update inventory, for example, an e-commerce business might use Lambda.
  
• Image/Video Processing: Uploads to Amazon S3 can initiate Lambda functions. Lambda can be used, for example, by photo-sharing software to automatically resize submitted images, make thumbnails, or apply various filters.
  
• Web Application Backends: Lambda functions are suitable for basic web app tasks like processing feedback forms. Upon submission, a Lambda can trigger to handle feedback processing and notification tasks efficiently.
  
• Internet of Things (IoT): Lambda functions can process IoT device data in smart home systems. For example, when a motion sensor detects activity, Lambda triggers actions like turning on lights or adjusting the thermostat, enhancing automation and responsiveness.

Conclusion

In conclusion, AWS Lambda and API Gateway are powerful tools for building serverless applications. Lambda allows you to write code that executes in response to events, while API Gateway provides a managed service for creating APIs that connect to your Lambda functions. By following the steps outlined above, you can develop and deploy serverless applications that are scalable, cost-effective, and easy to maintain.