API Rate Limiter

This is my attempt at building an API rate limiter. This is part of the Coding Challenges where I'm taking up the challenge to build a rate limiter as a way to learn a new language. For this, I've chosen Rust as I want to keep on building more experience in Rust.

Stack

• Axum
• Serde

Features

• Two endpoints: /limited and /unlimited.

To run

Assumption: You've installed Rust.

Run:

cargo run

Challenge 1: Token Bucket

The algorithm for token bucket is (taken from the challenge website):

• There is a ‘bucket’ that has capacity for N tokens. Usually this is a bucket per user or IP address.
• Every time period a new token is added to the bucket, if the bucket is full the token is discarded.
• When a request arrives and the bucket contains tokens, the request is handled and a token is removed from the bucket.
• When a request arrives and the bucket is empty, the request is declined.

The idea is to create a bucket (with capacity of 10 tokens) per IP address and increment it at a rate of 1 token per second.

How I implemented it?

First I created two endpoints: /api/limited and /api/unlimited. Then, I created a struct to store the bucket and an id to identify each user per request. To implement the algorithm, I created a middleware layer for the /api/limited. This allowed me to isolate the logic of identifying and checking the user's token bucket from the business logic.