Serverless FizzBuzz API

This project is a FizzBuzz game implementation using serverless pattern.

Installation/deployment instructions

Depending on your preferred package manager, follow the instructions below to deploy your project.

Using NPM

Run npm i to install the project dependencies
Run npx sls deploy to deploy this stack to AWS

Using Yarn

Run yarn to install the project dependencies
Run yarn sls deploy to deploy this stack to AWS

Test your service

This project contains a single lambda function triggered by an HTTP request made on the provisioned API Gateway REST API /fizzbuzz route with POST method. The request body must be provided as application/json.

requesting /fizzbuzz without a valid X-Api-Key header will result in API Gateway returning a 403 HTTP error code.
sending a POST request to /fizzbuzz with a payload not containing a number property named number and greater than 0 will result in API Gateway returning a 400 HTTP error code.
sending a POST request to /fizzbuzz with a payload containing a number property named number will result in API Gateway returning a 200 HTTP status code with a result being either "fizzbuzz", "fizz", "buzz" or the number from request.

⚠️ The deployed service requires an API Key to execute the lambda through API Gateway.

Locally

In order to test the fizzbuzz function locally, run the following command:

npx sls invoke local -f hello --path src/functions/hello/mock.json if you're using NPM
yarn sls invoke local -f hello --path src/functions/hello/mock.json if you're using Yarn

Check the sls invoke local command documentation for more information.

Or using serverless-offline plugin to serve it locally (Test your requests against http://localhost:3000):

npm start if you're using NPM
yarn start if you're using Yarn

Remotely

Copy and replace your url - found in Serverless deploy command output - and name parameter in the following curl command in your terminal or in Postman to test your newly deployed application.

curl --location --request POST 'https://xxxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/fizzbuzz' \
--header 'Content-Type: application/json' \
--header 'X-Api-Key: {SERVICE_API_KEY}'
--data-raw '{
    "number": 22
}'

Project features

Cloud deployment structure

The project was developed using many AWS core services, like:

Lambda - Functions to handle business logic
API Gateway - Service to handle HTTP connections and trigger lambda functions
Cloudwatch - Monitoring service for API Gateway and lambda usage (logs)
X-Ray - For debugging, it tracks requests end-to-end and represent it in a visual and dynamic way

And it's organized in the following way:

Project structure

The project code base is mainly located within the src folder. This folder is divided in:

functions - containing code base and configuration for your lambda functions
libs - containing shared code base between your lambdas

.
├── src
│   ├── functions               # Lambda configuration and source code folder
│   │   ├── fizzbuzz
│   │   │   ├── factory         # `FizzBuzz` factory functions to create resources
│   │   │   ├── mock            # `FizzBuzz` lambda input parameters, if any, for local invocation
│   │   │   ├── app.ts          # `FizzBuzz` express app and middlewares definition
│   │   │   ├── handler.ts      # `FizzBuzz` lambda http server adapter creation
│   │   │   ├── helpers.ts      # `FizzBuzz` common functions to help handle requests
│   │   │   ├── routes.ts       # `FizzBuzz` express routes definition and handlers mapping
│   │   │   ├── service.ts      # `FizzBuzz` service layer definition for business logic
│   │   │   └── validation.ts   # `FizzBuzz` lambda input event JSON-Schema for validation
│   │   │
│   │   └── index.ts            # Import/export of all lambda configurations
│   │
│   └── libs                    # lambda shared code
│       ├── adapters            # external libraries adapter for common usage
│       ├── helpers             # common helper functions
│       ├── middlewares         # common middlewares
│       └── protocols           # interfaces definitions for lambda functions 
│
├── package.json
├── serverless.ts               # Serverless service file
├── tsconfig.json               # Typescript compiler configuration
└── tsconfig.paths.json         # Typescript paths

3rd party libraries

express - used to handle http requests from AWS API Gateway
serverless-http - used to adapt serverless framework with an http server application
celebrate - express middleware function to validate incoming requests
@serverless/typescript - provides up-to-date TypeScript definitions for your serverless.ts service file

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