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Let's create a REST API with AWS Lambda, API Gateway, and DynamoDB


I recently started learning AWS serverless. Hence thought to write a little about creating an API in a serverless way. In this post, I am using the manual process, even though it is not the best practice. On a later topic, we will use IaC to build the same.

What is serverless?

Serverless computing means that the cloud provider manages all the necessary infrastructure as the developers can concentrate on the business logic. This does not mean that there are no servers but we developers do not manage them.

What is Lambda

AWS Lambda is a serverless, event-driven, compute service that lets you run code without provisioning or managing servers.

What API Gateway

AWS API Gateway is a fully manages service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. It acts as the "front door" for applications to access backend services.

What is DynamoDB

AWS DynamoDB is a fully manages, serverless, key-value NoSQL database designed to run high-performance applications at any scale.

What we will build

We will build a very simple REST endpoint to fetch all data from DynamoDB. I assume that you already have an AWS account.

Let's create the DynamoDB table

Our first step is to create a table in DynamoDB. After that, we will insert a few records manually so that we can fetch those using our REST API.

Go to DynamoDB and select created the table.

Now, select the created table and select "explore items". 

Using "add new attributes" we can add our extra fields. After filling click on "create item".

Let's create our Lambda function

Our second step is to create a Lambda function to fetch our notes from the DynamoDB table.

  • Create Lambda function
  • Update Role to give DynamoDB access
  • Create Node.js function to fetch data
  • Deploy

Goto Lambda and click on create function.

Now go to Configuration -> Permissions -> Execution role to add DynamoDB access.

Here we import managed policy and select DynamoDBFullAccess. Note that this is not the best practice. We should not give additional access but our purpose here is to learn.

After that, go to Code and add node.js code to fetch all items from our table.

const AWS = require('aws-sdk');
const documentClient = new AWS.DynamoDB.DocumentClient({region: 'us-east-1'});

function response(statusCode, data) {
    return {
        body: JSON.stringify(data),

exports.handler = async (event) => {
    try {
        let params = {
            TableName: 'notes_table'
        const data = await documentClient.scan(params).promise();
        return response(200, data);
    } catch (err) {
        console.log("Error", err);
        return response(500, "error occured");

After that click on the "Deploy" button to deploy the Lambda function.

Let's create a REST endpoint using API Gateway

Now it is time to create our REST API using API Gateway.

  • Create API
  • Create resource
  • Create HTTP method
  • Connect with Lambda
  • Create stage and deploy

Go to API Gateway and choose REST API.

Choose the REST option and New API from the next page.

With that our setup is created without resources. Hence under our API -> Resources, add a new child resource as below.

After creating the resource, we need to define our methods using the Actions -> create method. Choose "GET" as the method.

Now select the created "GET" method to connect our endpoint with the Lambda function. Remember to check "Use Lambda Proxy integration".

The next step is to deploy the API. Go to Actions -> Deploy API and deploy it.

Test it

With that everything is connected. Use postman or any client to access it. You can see the endpoint after deploying.


That is all for today. It is easy. However, this is not the best practice as we need to manually do this every time. Hence we will use a Serverless framework next time.
Remember to delete your resources.

Happy Learning ☺