Master Nginx Rate Limiting: Token Bucket Explained with Real Config

Nginx is an essential middleware for large‑scale architectures. This article explains the principle of Nginx rate limiting, its goals, and how it protects servers from overload and malicious attacks.

Nginx Rate Limiting

Rate limiting (Rate Limiting) restricts the frequency of client requests within a certain time period.

The core goal is to control request rate or concurrent connections to safeguard the server.

Principle

Nginx rate limiting is implemented based on the Token Bucket algorithm, which allows limited bursts while smoothing request rates.

Token Bucket Workflow

The algorithm maintains a bucket with a fixed capacity of tokens.

Tokens are added to the bucket at a constant rate.

Each incoming request must take a token from the bucket to be processed.

If there are insufficient tokens, the request is rejected or delayed.

The bucket capacity limits the number of stored tokens; excess tokens are discarded.

Configuration Example

limit_conn_zone $binary_remote_addr zone=conn_zone:10m;

server {
    location /download/ {
        limit_conn conn_zone 2;
        proxy_pass http://fileserver;
    }
}