AxiomZen Mastermind API

AxiomZen's challenge 1 @vanhackaton

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Mastermind-API Backend

AxiomZen's challenge @vanhackaton

The challenge was to build a reliable, scalable and well-tested API in which many users can play [mastermind](https://en.wikipedia.org/wiki/Mastermind_(board_game) with, along with multiplayer feature and any interesting add-on that we think it could fit.

Tech Stack

In order to fulfill the requirements, I built my entire API in a serverless architecture within Amazon Web Services that offers a easily-scalable and well managed structure.

Chosen Stack:

  • Node.JS
  • AWS Lambda
  • AWS DynamoDB (NoSQL)
  • AWS API Gateway

With it all set up, we have some key benefits:

  • Scale-up is one click away, both for logic (Lambda) and for database read OR write ops (DynamoDB)
  • HTTP Codes can be fully handled with API Gateway
  • Security: Amazon takes care of CORS, authentication and throttling for us
  • Caching: You can use cache in some cases so you don't punish your backend again and again.

How to Play & API Reference

API Host: https://p4392fkvs9.execute-api.us-east-1.amazonaws.com/prod

1. Create an User

You can't play, create or join games without having a user key, so that is the first thing you'll need to do so the game can keep your scores and join other games:

POST /user

Request: 

{
 userName: John Fogerty
}

Response:

{
  userName: John Fogerty,
  userKey: b000f510-2064-11e6-bd1d-395810d0c754
}

2. Create a Game

If you want to create a game, call this resource giving your userkey and name:

POST /new-game

Request: 

{
    userKey: b000f510-2064-11e6-bd1d-395810d0c754
}

Response:

{
  gameKey: 26f624b0-2065-11e6-b7ab-ab2f614c58,
  userKey: b000f510-2064-11e6-bd1d-395810d0c7,
  possible_colors: RBGYOPCM,
  code_length: 8
}

3. Join an Existing Game

You can join your friends in a game, all you must have is their gameKey and your userKey. You can only join games before the first guess is made (fair, isn't?) .

POST /join-game

Request: 

{
    userKey: b000f510-2064-11e6-bd1d-395810d0c754,
    gameKey: 20a1a8f0-2065-11e6-b7ab-ab2f614c583d
}

Response:

{
    userKey: b000f510-2064-11e6-bd1d-395810d0c754,
    gameKey: 20a1a8f0-2065-11e6-b7ab-ab2f614c583d
}

4. Making guesses

Once you are in a game, you can make guesses to it and the API will tell you the exacts and nears, along with your past guesses. They expire 5 minutes after the first guess is made and the first user to break the code wins. Unlimited guesses.

POST /guess

Request: 

{
    userKey: b000f510-2064-11e6-bd1d-395810d0c754,
    gameKey: 20a1a8f0-2065-11e6-b7ab-ab2f614c583d,
    code: RRGGBBRR
}

Response:

{
    gameKey: 4e50da60-2046-11e6-a631-a1f850bfa9f1,
    userKey: b000f510-2064-11e6-bd1d-395810d0c754,
    past_guesses: [
        {
            exact: 0,
            near: 0,
            code: RRGGBBRR
        }
    ],
    num_guesses: 1,
    solved: true,
    time: 59 secs,
    score: 598
}

5. See the ranking

Since we ask you to create an user, we can save data such as you score. It is cumulative and the faster you break the code, better!

GET /ranking

Response:

[
    {
        UserName: John Fogerty,
        Score: 598
    },
    {
        UserName: Other Dude,
        Score: 356
    }
]

Set up the environment

The Lambda function codes are in the github repo;

The DynamoDB Tables (screenshot in github repo):

User: Partition Key "UserKey"

Mastermind: Partition Key "GameKey"

The API Gateway resources are set up one for each lambda function.

Questions, suggestions or feedback feel free to contact me at any time stefano.bourscheid@gmail.com

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