Mastering Nginx High Availability: Master‑Slave Architecture Explained

Nginx Master‑Slave Overview

In Nginx, “master‑slave” refers to a high‑availability architecture that uses two or more Nginx servers: one acts as the Master and the others as Slave/Backup servers.

The goal is to keep the service available when the master becomes unavailable due to hardware failure, network interruption, or software crash. Traffic is automatically switched to the slave, avoiding a single point of failure.

How It Works

The master holds a virtual IP (VIP) that serves as the entry point for clients. The slave servers do not expose the service directly; they bind to the same VIP. When the master fails, a slave takes over the VIP, seamlessly handling all traffic.

Keepalived Integration

Implementing Nginx high availability typically involves Keepalived, which monitors network interfaces and performs health checks on Nginx processes via scripts. If Keepalived detects a failure, it triggers VIP migration to the backup server.

Keepalived is based on the VRRP protocol and can create a virtual IP that floats between servers.

In summary, Nginx itself does not provide built‑in master‑slave functionality; the “master‑slave” concept is realized through external high‑availability tools like Keepalived, which enable automatic failover and continuous service availability.