Scalable Architecture with AWS APIGateway, Lambda And DynamoDB

How To Create A scalable Architecture With In AWS Using API-Gateway, Lambda & DynamoDB

AWS provides many managed services using which you can create a massively scalable architecture with very minimal effort. Here in this posts we will use three AWS managed services to create a simple application which can scale very easily. Let's get going...

Create DynamoDB Table

• The very first step is to create a DynamoDB  table. 
• Create a table, give it a name - "myinfo"
• Leave the "type" to string
• Leave other settings to default
• Click on "create" button to create the table

• After creating table, you will see the following table details

Create Lambda Function

• Open Lambda console, click on "create function" button
• Do not select any blueprint, click on "Author From Scratch" button

• Give the function name "myinfo"
• In Role section select "choose from existing role"
• Then select "dynamo_access" role (This role is being already created by us. You need to create this explicitly by attaching dynamodb full access policy to this role)
• Now click on "create function" button

• Now in the function code, paste the code from the below gist

	console.log('Loading event');
	var AWS = require('aws-sdk');
	var dynamodb = new AWS.DynamoDB();
	exports.handler = function(event, context) {
	console.log("Request received:\n", JSON.stringify(event));
	console.log("Context received:\n", JSON.stringify(context));
	var tableName = "myinfo";
	var datetime = new Date().getTime().toString();
	dynamodb.putItem({
	"TableName": tableName,
	"Item": {
	"name": {
	"S": event.name
	},
	"timedate": {
	"N": datetime
	}
	}
	}, function(err, data) {
	if (err) {
	context.fail('ERROR: Dynamo failed: ' + err);
	} else {
	console.log('Dynamo Success: ' + JSON.stringify(data, null, ' '));
	context.succeed('SUCCESS');
	}
	});
	}

view raw dynamo_lambda.js hosted with ❤ by GitHub

• Select runtime as "Node.js 6.10" and leave handler as default

• Now click on "save and test"
• This will open a modal to create a test-event, give the event name myinfo.
• Put the below data in the text-pane    -    {"name": "appychip"}
• Now click on "create"

• Click on "Test" button and you will see the lambda is getting executed and prints out "SUCCESS" if executed successfully.

• You can also check DynamoDB table "myinfo", the entry for {"name": "appychip"} got created when you executed this function.

Create API-Gateway

• The last step is to create an API-Gateway which will give us an api to trigger lambda function which then on successful execution make an entry in DynamoDB.
• Open API-Gateway console.
• Click on "create" button to create an API. Give API name as "myinfo" and put some description and click on "create API" button

• After creating the API, click on "Action" dropdown and select on "create method", then in method dropdown select "POST" and finally click on small right icon to create the method.

• Now after creating method, It will ask for integration type, choose "Lambda function" and select the region in which "myinfo" lambda function was created (ap-south-1) in our case.
• Select the lambda function "myinfo"
• click on "save" button

• A pop-up will appear, click on "Ok"
• Now you will see a screen something like shown below

• Click on "Test" (below the small yellow circle)
• This will open a text pane for "Request Body" to provide the json content for the POST request.
• put the below json data  -   {"name": "test-name"}

• Now click on "Test" button
• This will trigger the Lambda function and will create an entry in DynamoDB table for {"name": "test-name"}
• The logs should show "SUCCESS" message as shown below:

• We have created our API successfully.
• Now, let's deploy our API for testing environment
• Click on "Action" dropdown
• Select "Deploy API"

• In Deployment stage dropdown, select "[New Stage]"
• Give "Stage name" as "testing". Put some description if you want.
• Click on "Deploy" button

• This will generate a URL on which we can hit a POST request.

• Click on "Save Changes" button
• Now you can make a curl request from your terminal to check if your API is working or not as shown below:
• curl -H "Content-Type: application/json" -X POST -d "{\"name\":\"curl-name\"}" https://de5w3pouo9.execute-api.ap-south-1.amazonaws.com/testing

• This should return "SUCCESS" and you will see the "curl-name" in DynamoDB table "myinfo"

Hurray!!! You have successfully created the Demo App which involve AWS API-Gateway, Lambda and DynamoDB.