tic-tac-toe-api

REST API for playing Noughts and Crosses (a.k.a Tic-tac-toe), built for Ethyca's Technical Challenge

Play through the browser UI or interact directly with the deployed API

You can play Tic-Tac-Toe with a React client that is integrated with this API here: Play Tic-Tac-Toe Here!
This API is deployed here: https://tic-tac-toe-api.nreyes.dev/api

You can check out the front-end code here: https://github.com/nreyes-dev/tic-tac-toe-react-client

Instructions on how to run this locally:

Make sure you have Docker installed and running in your system, then do:

cp .env.example .env
docker compose -f docker-compose.dev.yaml up --build -d

You should now see the api running in http://localhost:8080

You can also look at the logs by doing:

docker compose -f docker-compose.dev.yaml logs api -f

Using the api.http File (VS Code REST Client)

This project includes an api.http file that makes it very easy to try the API directly from VS Code using the REST Client extension. In case you don't this extension: it basically turns a .http file into a mini Postman collection. You'll find the four available endpoints there. You can hit both the deployed API or a locally running one from there. If you prefer to use Postman/Insomnia, curl, or anything else, you can use api.http just as documentation.

Player Identification (Important)

Since this project does not implement authentication (to keep the scope appropriate for the challenge), player identity is tracked using a lightweight mechanism:

• When you create a game (POST /game), if you do not send an X-Player-Id header, the server will automatically generate a new player ID.
• Any client (CLI, Postman, REST Client, browser frontend) should store this value and include it as a header in subsequent requests.

General comments about my thought process when building this

Architecture Decisions & Tradeoffs

The feature that immediately stood out as a potential challenge was the "view all games I played in chronological order" one. The issue here is that, without including authentication (which I imagine would be overkill and not what's expected from this assignment) I'm forced to either store and show all games together as if multiple different players are not possible, or have a way to assign identifiers to different users.
I decided on generating a player id and then the client is instructed to include it as an "X-Player-Id" header. Not including this header will result in each game generating a new player id and each game living in a different game history. I see this as a reasonable tradeoff, the responses can include this and any client can easily store the id so that it can continue to use it. I plan to also build a browser client for this so soon enough I'll be able to demonstrate this.
Again, in a real project I would add authentication but that would require a database like PostgreSQL or MongoDB, encoding/decoding JWT, hashing and storing passwords, signup/login endpoints etc, or using something like AWS Cognito, and I'm pretty sure that's way overkill. I'll stick with a simple Redis container to store game data there (I could've also just stored everything in Python in-memory data structures but I want to at least make it somewhat resemble a real app). I will set a TTL of 24hs for the game data, which should be enough for the purposes of this test, although again, in a real world tic tac toe project (if that was a thing) we would probably want to completely persist the history of our players in a database.

Gameplay & Behavior

It's not explicitly stated whether the player is always supposed to start the game. I decided to randomize whether the player or the CPU makes the first move. Other than that, I pretty much stuck to the basics. The CPU just makes random moves as suggested in the challenge description.

Time spent on this project

Coding the backend (this project) took about 4 hours. Deploying the API to the cloud and building/deploying the front-end client took another two hours or so, but I don't consider that part of the main task given that it's not really a requirement and more like an extra I felt really tempted to do.
So I would say about 4 hours of time spent on the actual main assignment, or ~6 hours total if we include the extra stuff.

Run unit tests

Connect to the running container:

docker exec -it api /bin/bash

Once inside it, run:

chmod +x tests/run_tests.sh
./tests/run_tests.sh