Creating a Distributed Rate Limiter in Elixir Using HashRing

This article discusses how to create a distributed rate limiter in Elixir that can manage requests across multiple nodes in a cluster. It begins with an overview of message passing in the Erlang VM, emphasizing that communication between processes remains consistent regardless of whether they are on the same node or across different nodes in a cluster. The author demonstrates how to implement a basic rate limiter using the Hammer library, which initially restricts requests to a single node. However, this approach becomes inadequate as nodes scale up, leading to potential request overflows. The article provides a solution by utilizing HashRing, a distributed algorithm for consistently associating keys with nodes. It details the steps to set up interconnected Elixir nodes, create a GenServer for maintaining the hash ring, and upgrade the rate limiting logic to accommodate distributed state across the cluster. The author stresses that this approach, while effective for certain use cases, may not be universally applicable. The article encourages readers to explore further applications for distributed Elixir beyond rate limiting.