Serverless API Made Simple: A Beginner's Guide to Creating Your First API with AWS Lambda and API Gateway

Create your first serverless API with ease using the power of AWS Lambda and API Gateway with this comprehensive guide

Jan 12, 2023

Hello Backend Developers,

In this edition of our newsletter, we're going to explore the exciting world of serverless and how it can make your life as a backend developer easier and more efficient!

What is Serverless?

Serverless is a cloud computing model in which the cloud provider is responsible for managing and allocating the servers, allowing you to focus on building and running your application. Instead of managing and provisioning servers, you can simply deploy your code and let the cloud provider handle the scaling and availability.

Benefits of Serverless

Pay-per-use pricing model, only pay for what you use.
Auto-scaling can handle sudden spikes in traffic.
Reduced operational overhead, no need to manage servers.
Easier to build and deploy microservices.
Easy to implement CI/CD (Continuous Integration and Continuous Deployment)

Design Diagram

Here's a simple design diagram that illustrates a serverless architecture:

In this diagram, the client app makes a request to the API Gateway which triggers a Lambda function. The Lambda function processes the request and returns a response. The Lambda function can be triggered by a variety of events such as an HTTP request, an S3 file upload, a database change, etc.

Step-by-step guide for creating a serverless API using AWS Lambda and API Gateway:

Create an AWS account if you don't already have one.
Install the AWS CLI (Command Line Interface) by following the instructions in this link: https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-install.html
Use the AWS CLI to configure your credentials by running the following command:

aws configure

You will be prompted to enter your AWS Access Key and Secret Access Key, as well as the region you want to use.

Create a new directory for your project and navigate to it in the terminal:

mkdir my-serverless-project
cd my-serverless-project

Create a new file called lambda_function.py and add the following code:

import json

def lambda_handler(event, context):
    name = event['queryStringParameters'].get('name', 'World')
    response = {
        'statusCode': 200,
        'body': json.dumps({'message': f'Hello, {name}!'}),
        'headers': {
            'Content-Type': 'application/json',
        },
    }
return response

This is the code for your Lambda function. It extracts the name query parameter from the event and returns a JSON response with the greeting message.

Create a new file called template.yml and add the following code:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: lambda_function.lambda_handler
      Runtime: python3.8
      Events:
        Api:
          Type: Api
          Properties:
            Path: /
            Method: get

This is the AWS CloudFormation template for your project. It creates a new AWS Lambda function and an API Gateway REST API that maps to it.

Package and deploy your project using the following command:

aws cloudformation package --template-file template.yml --output-template-file output.yml --s3-bucket <your-s3-bucket>
aws cloudformation deploy --template-file output.yml --stack-name my-serverless-project --capabilities CAPABILITY_IAM

This command will package your Lambda function and template into a zip file, upload it to an S3 bucket and then deploy it to your AWS account using CloudFormation. Make sure to replace <your-s3-bucket> it with the name of the S3 bucket you want to use.

Once the deployment is complete, you should see an output with the URL of your new API Gateway endpoint. You can test it by making a GET request to the endpoint with a query parameter named name:

curl https://<api-id>.execute-api.<region>.amazonaws.com/Prod/hello?name=YourName

You should see a response like this:

{"message": "Hello, YourName!"}

And that's it! You have just created your first serverless API using AWS Lambda and API Gateway. Remember to remove resources created and S3 Bucket is no longer needed in order to avoid any charges.

Please note that this is a basic example, and there are many ways to improve and expand your serverless application, including security, monitoring, error handling, and other important aspects when building a production-ready serverless application.

If you want to learn more about the capabilities of AWS Lambda and API Gateway, or other serverless platforms, it's best to check the documentation.

Here are some references for further reading on serverless:

AWS Lambda - AWS Lambda - The official documentation for AWS Lambda, a serverless compute service from Amazon Web Services.
AWS Serverless Application Model (AWS SAM) - AWS - AWS SAM is an open-source framework for building serverless applications. It provides shorthand syntax to express functions, APIs, and infrastructure resources in a file called a template.
Getting Started with AWS Lambda and the Serverless Framework - A comprehensive tutorial on building a serverless application using the Serverless Framework, a popular open-source tool that makes it easy to build and deploy serverless applications.
Building a Serverless REST API with AWS Lambda and Amazon API Gateway - A step-by-step guide to building a serverless REST API using AWS Lambda and Amazon API Gateway.
Real-World Serverless - A collection of articles and resources on building, deploying, and operating serverless applications in production.

Each one of them provides good coverage on serverless and provides you with many examples and best practices that you can adopt.

As you can see, Serverless is a powerful and efficient way to build and deploy your applications and with the help of AWS Lambda and API Gateway, creating a serverless API is simple and straightforward.

We hope you enjoyed this post and that it has given you some insight into the world of serverless. As always, thank you for reading and we look forward to providing you with more informative content in the future.

The Backend Developers Newsletter