Comprehensive Guide to Nginx Load Balancing and Algorithms

Nginx is a high‑performance HTTP and reverse‑proxy server widely used for load balancing, caching, and serving static resources.

It distributes traffic among backend servers to improve availability and reliability.

Typical configuration uses an upstream block that lists the backend IPs, e.g.:

upstream backend {
    server 192.168.1.101;
    server 192.168.1.102;
    server 192.168.1.103 backup;
}

The article explains several load‑balancing algorithms:

Round Robin – default, sends requests sequentially to each server.

Weighted Round Robin – adds a weight parameter so servers with higher weight receive more requests.

IP Hash – hashes the client IP to consistently route the same client to the same server, useful for session persistence.

Least Connections – directs traffic to the server with the fewest active connections, ideal for long‑lived connections.

Example configuration for weighted round robin:

http {
    upstream mikechen {
        server server1.mikechen.cc weight=3; # receives more requests
        server server2.mikechen.cc weight=1;
        server server3.mikechen.cc weight=2;
    }
    server {
        listen 80;
        location / { proxy_pass http://mikechen; }
    }
}

Understanding these algorithms helps design scalable and resilient architectures.