NGINX Cookbook

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For those who have used older versions of NGINX, the ip_hash method is still available, but with one distinct difference. The ip_hash method uses the first three octets of an IPv4 address (for example, 1.2.3.XXX) to produce the hash map. This means that if the requesting IP comes from a different IP within the standard class C range, it'll be sent to the same upstream server. Here's an example of how it's implemented:

upstream localapp { 
    ip_hash; 
    server 127.0.0.1:8080; 
    server 127.0.0.1:8081; 
    server 127.0.0.1:8082; 
}  

While this method still works, if you need better consistency for ip_hash mapping, then using hash $remote_addr will match the full IP address.