Redis Rate Limit

A cats and zio friendly lightweight library that rate limits using token bucket algorithm. The library executes redis commands as Lua code which makes the operations atomic. The library internally creates and memoizes a redis client using scala-redis if redis client is not provided.

Importing

Add the following to your build.sbt

libraryDependencies =+ "io.github.ashwinbhaskar" %% "redis-rate-limit-ce" % "4.0.0" // If you use cats effect (3.x)

libraryDependencies =+ "io.github.ashwinbhaskar" %% "redis-rate-limit-zio" % "4.0.0" // If you use zio (2.x)

Usage

Let's take a look at a scenario where we have to rate limit an API call to 5 calls per user in a time window of 5 seconds.

ZIO

import zio._
import com.redis.RedisClient //From scala-redis library
import com.redis.ratelimit._ //This library

val apiCall: RIO[HttpClient, String] = ???

val userId: String = ???

//Externally provided Redis Client
val redisClient = new RedisClient("localhost", 6379)

val rateLimitedApiCall: RIO[HttpClient with RedisClient, String] = apiCall.withRateLimit(key = userId, maxTokens = 5, timeWindowInSec = 5)


// Internally used Redis Client
val redisHost: String = ???
val redisPort: Int = ???
val config = Config(redisHost, redisPort, maxTokens = 5, timeWindowInSec = 5)

val rateLimitedApiCall: RIO[HttpClient, String] = apiCall.withRateLimit(key = userId, config)

Cats Effect

import cats.effect.IO
import com.redis.RedisClient //From scala-redis library
import com.redis.ratelimit._ //This library


//Externally provided Redis Client
val host: String = ???
val port: Int = ???
implicit val redisClient: RedisClient = new RedisClient(host, port) //pass your own instance of redis client implicitely
val userId: String = ???

val apiCall: IO[String] = ???

val result: IO[String] = rateLimited[IO, String](apiCall, key = userId, maxTokens = 5, timeWindowInSec = 5)

//Internally Constructed Redis Client
val redisHost: String = ???
val redisPort: Int = ???
implicit val config = Config(redisHost, redisPort, maxTokens = 5, timeWindowInSec = 5)
val userId: String = ???

val apiCall: IO[String] = ???

val result: IO[String] = rateLimited[IO, String](apiCall, key = userId) //internally creates a redis client for the implicit config and keeps it in memory

result.handleErrorWith {
    case RedisConnectionError(msg) => ??? 
    case RateLimitExceeded => ???
}