Serverless URL Shortener

Core Features

• Generate code for shortened URL (/codes endpoint):

$ curl -X POST \
  -H "Content-Type: application/json" \
  -H "x-api-key: <api-key>" \
  -d '{"url": "https://really-long-url.com"}' \
  https://<api-gateway-id>.execute-api.<aws-region>.amazonaws.com/dev/v1/codes

> 95188452

• Retrieve url based on code (/urls endpoint):

$ curl https://<api-gateway-id>.execute-api.<aws-region>.amazonaws.com/dev/v1/urls/<code>

> "https://really-long-url.com"

• Enqueue url into SQS queue. Code generation process decoupled from API Gateway (CQRS approach):

$ curl -X POST \
  -H "Content-Type: application/json" \
  -H "x-api-key: <api-key>" \
  -d '{"url": "https://really-long-url.com"}' \
  https://<api-gateway-id>.execute-api.<aws-region>.amazonaws.com/dev/v1/urls/enqueue

> "url enqueued successfully"

CQRS Pattern

CQRS stands for Command and Query Responsibility Segregation, a pattern that separates reads and writes into different models, using commands to update data, and queries to read data.

query and upsert (updates or creates) responsibilities are split (segregated) into different services (e.g.: AWS Lambda Functions)

Technically, this can be implemented in HTTP so that the Command API is implemented exclusively with POST routes, while the Query API is implemented exclusively with GET routes.

Now, for high number of POST requests, an improvement on scalability is to decouple create Lambda function from DynamoDB table by adding an SQS Queue in between.

create Lambda function no longer writes to DynamoDB table directly.

Instead:

1. There's a new endpoint available: POST - /v1/urls/enqueue.
2. enqueue Lambda function sends url data into urls SQS Queue as message.
3. SQS Queue message is picked up by worker Lambda function.
4. worker Lambda function persists record into urls DynamoDB Table.

Setup

1. Clone repository.

2. Install and Configure Serverless framework:

https://www.serverless.com/framework/docs/getting-started

$ npm install -g serverless

3. CD into project folder:

$ sls deploy

Deploying serverless-url-shortener to stage dev (us-east-1)

✔ Service deployed to stack serverless-url-shortener-dev (84s)

api keys:
  dev-BasicPlanKey: xxxx (auto-generated value at deployment time)
  dev-FreePlanKey: yyyy (auto-generated value at deployment time)
  dev-PremiumPlanKey: zzzz (auto-generated value at deployment time)
endpoints:
  GET - https://zk4bac5f0b.execute-api.us-east-1.amazonaws.com/dev/v1/urls/{id}
  POST - https://zk4bac5f0b.execute-api.us-east-1.amazonaws.com/dev/v1/codes
  POST - https://zk4bac5f0b.execute-api.us-east-1.amazonaws.com/dev/v1/urls/enqueue
functions:
  getUrl: serverless-url-shortener-dev-getUrl (86 kB)
  createCode: serverless-url-shortener-dev-createCode (86 kB)
  enqueueUrl: serverless-url-shortener-dev-enqueueUrl (78 kB)
  urls-queueWorker: serverless-url-shortener-dev-urls-queueWorker (86 kB)
urls-queue: https://sqs.us-east-1.amazonaws.com/542979624611/serverless-url-shortener-dev-urls-queue

Naming conventions for files and functions

https://github.com/airbnb/javascript?tab=readme-ov-file#naming-conventions

Serverless Resources

SQS Queue and DLQ setup: https://github.com/getlift/lift/blob/master/docs/queue.md

References: https://github.com/serverless/examples/blob/v3/aws-node-sqs-worker/serverless.yml

CI/CD: https://github.com/serverless/github-action

Unit Testing: https://www.serverless.com/blog/unit-testing-nodejs-serverless-jest