Proxy cache path configuration in Nginx - Commands & Configuration

Introduction

Sometimes web servers need to speed up responses by saving copies of requested content. Proxy cache path configuration in Nginx sets where and how these copies are stored on disk to serve future requests faster.

When you want to reduce load on your backend servers by caching responses.

When you want faster response times for repeated requests to the same content.

When you want to control disk space used for caching to avoid filling up the server.

When you want to organize cached files efficiently for quick access.

When you want to set limits on cache size and expiration to keep content fresh.

Config File - nginx.conf

nginx.conf

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=my_cache:10m max_size=1g inactive=60m use_temp_path=off;

server {
    listen 80;
    location / {
        proxy_cache my_cache;
        proxy_pass http://backend_server;
        proxy_cache_valid 200 302 10m;
        proxy_cache_valid 404 1m;
    }
}

proxy_cache_path defines the directory where cached files are stored, the directory structure levels, the shared memory zone name and size, maximum cache size, and cache inactivity timeout.

Inside server, proxy_cache enables caching using the defined zone. proxy_pass forwards requests to the backend server. proxy_cache_valid sets how long responses with certain status codes are cached.

Commands

Check the Nginx configuration file syntax to ensure the proxy cache path settings are correct before reloading.

Terminal

sudo nginx -t

Expected Output

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok

nginx: configuration file /etc/nginx/nginx.conf test is successful

Reload Nginx to apply the new proxy cache path configuration without stopping the server.

Terminal

sudo systemctl reload nginx

Expected Output

No output (command runs silently)

Verify that the cache directory exists and check its contents and permissions.

Terminal

ls -l /var/cache/nginx

Expected Output

total 0

-rw-r--r-- 1 nginx nginx 0 Jun 10 12:00 1

-rw-r--r-- 1 nginx nginx 0 Jun 10 12:00 2

→

-l - Show detailed list including permissions and timestamps

Key Concept

If you remember nothing else from this pattern, remember: proxy_cache_path sets where and how cached files are stored on disk for faster repeated responses.

Common Mistakes

Not creating or giving proper permissions to the cache directory.

Nginx cannot write cached files, so caching fails silently or with errors.

Create the cache directory with correct ownership (usually nginx user) and permissions before starting Nginx.

Using the same keys_zone name in multiple proxy_cache_path directives.

Nginx will fail to start because keys_zone names must be unique.

Use unique keys_zone names for each proxy_cache_path directive.

Not testing configuration with 'nginx -t' before reload.

Syntax errors cause Nginx reload to fail, leading to downtime.

Always run 'sudo nginx -t' to verify configuration before reloading.

Summary

Define proxy_cache_path in nginx.conf to specify cache storage location and parameters.

Test configuration syntax with 'nginx -t' before reloading Nginx.

Reload Nginx to apply changes and verify cache directory contents.