Master Nginx Upstream Load Balancing and Caching: Step‑by‑Step Guide

Outline

Introduction

Experiment Topology

Experiment Environment

Nginx Upstream Module Introduction

Nginx Cache Introduction

Conclusion

Introduction

This article continues the previous Nginx series, demonstrating how to use Nginx as a load balancer and cache. The experiment does not cover all scenarios such as data synchronization between web servers.

Experiment Topology

Experiment Environment

Host          IP Address     Function lb.anyisalin.com  172.16.1.2  Load balancer and cache static resources web1.anyisalin.com  172.16.1.3  Provide web service web2.anyisalin.com  172.16.1.4  Provide web service

Note: All operations are performed with SELinux and iptables disabled

Nginx Upstream Module Introduction

The ngx_http_upstream_module module is used to define groups of servers that can be referenced by the proxy_pass , fastcgi_pass , uwsgi_pass , scgi_pass , and memcached_pass directives. (Excerpt from official documentation)

In short, the upstream module defines a server group that can be combined with other proxy modules to achieve load balancing.

How to Use Upstream

Below is a simple upstream definition that provides basic load‑balancing functionality.

upstream servers {
    server 172.16.1.2;
    server 172.16.1.3;
}

location / {
    proxy_pass http://servers;
}

Common upstream parameters

upstream name {
    [ip_hash]
    server address [weight=number] [max_fails=number] [fail_timeout=number] [down|up|backup];
    ...
}

# ip_hash: similar to LVS's sh algorithm, directs the same IP to the same host
# weight: weight setting
# max_fails: number of failed connections before marking a server down
# fail_timeout: timeout considered as failure
# down: take server offline
# backup: set server as backup (used only when primary servers are down)

Upstream Usage Example

Installation of nginx is omitted; see the previous blog for details.

# Add to nginx main configuration
http {
    upstream servers {
        server 172.16.1.3;
        server 172.16.1.4;
    }
}

server {
    location / {
        proxy_pass http://servers;
    }
}
# Reload nginx

See the image; we achieved a simple load‑balancing effect using different pages.

Nginx Cache Introduction

Cache is king; the Nginx proxy module supports caching static resources, reducing server load and speeding up responses.

Caching Static Resources

proxy_cache_path /cache levels=1:1 keys_zone=mycache:64m;   # http block

location /index.html {  # location block
    proxy_pass http://172.16.1.3;
    proxy_cache mycache;   # use mycache
    proxy_cache_valid 200 1d;   # cache 200 responses for 1 day
    proxy_cache_valid 500 501 502 503 1m;   # cache error responses for 1 minute
    proxy_cache_use_stale error;   # use stale cache if origin fails
}

mkdir /cache
chown nginx:nginx /cache

Testing shows that caching significantly improves the response time of static resources.

Conclusion

Due to time constraints, this article briefly introduced Nginx upstream and cache usage; many configuration parameters were not detailed. Future posts will cover them in depth, and the Nginx series will continue—stay tuned!