Architecture

Introduction

We'll walk through the process of building a URL shortener service using (serverless architecture) AWS Lambda (python : boto3) and API Gateway (http). By the end of this tutorial, you'll have a fully functional URL shortener service that you can deploy and use to shorten URLs.

Prerequisites

Before we begin, ensure that you have an AWS account set up and that you're familiar with basic AWS services like Lambda and API Gateway.

Step 1: Create a Lambda Function:

The first step is to create a Lambda function that will generate short URLs for long URLs. Here's a Python code snippet for the Lambda function

import json
import boto3
import string
import random

dynamodb = boto3.resource('dynamodb')
table_name = 'url-shortener-table'
table = dynamodb.Table(table_name)

def lambda_handler(event, context):
    print(event)

    http_method = event['requestContext']['http']['method']

    if http_method == 'POST':
        body = json.loads(event['body'])
        long_url = body['long_url']
        short_url = generate_short_url()
        table.put_item(Item={'short_id': short_url, 'long_url': long_url})

        response = {
            'statusCode': 200,
            'body': json.dumps({'short_url': short_url})
        }
    elif http_method == 'GET':
        short_url = event['rawPath'][1:]
        response = table.get_item(Key={'short_id': short_url})
        if 'Item' in response:
            long_url = response['Item']['long_url']
            response = {
                'statusCode': 301,
                'headers': {
                    'Location': long_url
                }
            }
        else:
            response = {
                'statusCode': 404,
                'body': json.dumps({'error': 'Short URL not found'})
            }
    return response

def generate_short_url():
    characters = string.ascii_letters + string.digits
    short_url = ''.join(random.choice(characters) for _ in range(3))
    return short_url

NOTE : Replace table_name with your dynamoDb table name once we create it later in this steps . and partitionKey should be short_id

Step 2: Set Up DynamoDB Table:

Create a DynamoDB table named url-shortener-table with short_id as the partition key and long_url as an attribute.

Step 3: Create an API Gateway:

Lets create api first and later we can do configuration

Open the API Gateway console.

Click on "Create API" and select "HTTP API". Review and create api
Once we created API Define routes for POST and GET requests.

Select create and keep route empty and method POST then select create

ref following image

once created select POST like this

click on attach integration and go ahead with option

create and attach integration
Next select integration type as lambda function and then select lambda function created earlier for this task
Make sure this option is enabled and go ahead with create option

Cool we just created our first route , lets go and create second route which is GET

for redirecting shorturl we got in previous response
Lets create second route , now go back to Routes and select create

Make sure its /{short_id}
Now select GET Method attach integration and click on attach just right side option
From this option you can get your APIGW url to make request
These are the curls to test Replace url with actual url

Create Short Url : POST

curl --location 'https://4tr7c6bru76e.execute-api.us-east-1.amazonaws.com' \
--header 'Content-Type: application/json' \
--data '{"long_url": "https://cloudcdk.com"}'

Access Short Url : GET

curl --location 'https://4tr7c6bru76e.execute-api.us-east-1.amazonaws.com/{Replace_with_id_u_get_in_response_for_above_post_request}'

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Serverless Url Shortener apiGW Lambda dynamoDb

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Akash Pawar

Akash Pawar