Building a serverless API with AWS API Gateway and Lambda Functions

image credit: codeburst.io

In recent years, serverless architecture has become increasingly popular as a way to build and deploy applications. One of the key benefits of serverless is the ability to scale and pay only for the resources you use. In this article, we will explore how to build a serverless API using AWS API Gateway and Lambda Functions.

First, let’s understand what AWS API Gateway and Lambda are:

• AWS API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale.
• AWS Lambda is a serverless computing service that runs your code without provisioning or managing servers and automatically scales your applications in response to incoming requests.

Now let’s build a simple serverless API that returns a “Hello from Lambda!” message when a user makes a GET request to the endpoint.

Step 1: Create a new Lambda function

First, log in to the AWS Management Console and navigate to the Lambda service. Click on the “Create function” button.

On the “Create function” page, select “Author from scratch” and give your function a name, such as “HelloWorldFunction”. For the runtime, select “Node.js 18.x” or the runtime of your choice. Click on the “Create function” button.

Create an AWS Lambda function

Step 2: Write the code for your Lambda function

In the “Function code” section, replace the sample code with the following:

export const handler = async(event) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

When the function is invoked, this code returns a “Hello from Lambda!” message with a 200 status code.

Step 3: Create an API Gateway

Next, navigate to the AWS API Gateway service and click on the “Build” button in the REST API section.

• Select “REST” as the protocol
• “New API” in the second section
• Give your API a name, description and select the endpoint type
• and click on the “Create API” button.

Step 4: Create a resource and method for your API

In the next step, you’ll create a resource for your API. A resource represents an endpoint, such as /items or /users. For this example, we’ll create a resource called “hello” and a “GET” method.

In the “Actions” menu, select “Create Method” and choose “GET” from the dropdown menu. In the “Integration type” section, select “Lambda Function” and enter the name of your Lambda function in the “Lambda Function” field.

Step 5: Deploy your API

Once the API Gateway is connected to your Lambda function, you can deploy your API. In the “Actions” menu, select “Deploy API” and create a new deployment stage, such as “prod”.

Step 6: Test your API

You can now test your API by making a GET request to the endpoint provided by the API Gateway. You should see a response with a status code of 200 and a body of “Hello from Lambda!”.

Congratulations! You have now built a serverless API using AWS API Gateway and Lambda Functions.

This is a simple example of how to create an API with AWS API Gateway and Lambda functions. However, in reality, you may have multiple endpoints and multiple functions that handle different requests.

It’s important to note that we’ve just scratched the surface of what’s possible with AWS API Gateway and Lambda Functions. There are many advanced configuration options and features that can be used to customize further and optimize your serverless API.

For example, you can use AWS API Gateway to create custom domains and use your own SSL/TLS certificates or route requests to different Lambda functions based on the request path or headers. You can also use AWS Lambda to create custom authorizers and to use environment variables to store and retrieve configuration settings.

Additionally, you can use AWS API Gateway to create and manage APIs that use other protocols, such as WebSockets and HTTP/2. You can also use AWS Lambda to build event-driven applications that can respond to changes in data stored in other AWS services, such as S3, DynamoDB, and Kinesis.

Furthermore, you can take advantage of other AWS services, such as AWS Cognito for user authentication, AWS DynamoDB for storing data, and AWS S3 for file storage.

You can also use AWS CloudFormation or AWS CDK to automate the creation and deployment of your API Gateway and Lambda functions. This can help you to manage and version your infrastructure and to make it easier to test and roll back changes.

It’s also important to consider security when building a serverless API. AWS API Gateway provides built-in support for authentication and authorization using AWS Identity and Access Management (IAM) and Amazon Cognito. You can also use AWS WAF to protect your API from common web attacks and use AWS CloudTrail to log and monitor the usage of your API.

In summary, building a serverless API with AWS API Gateway and Lambda Functions is a great way to create and deploy scalable and cost-effective APIs quickly. With the ability to connect to other AWS services and the use of automation tools, it’s possible to build robust and secure APIs that can handle a high volume of requests.

If you’re interested in learning more about how to build and deploy serverless APIs with AWS API Gateway and Lambda Functions, there’s a lot of documentation and tutorials available on the AWS website and many examples and open-source projects available on Github. Feel free to comment and ask any questions; I’ll be happy to help answer them.