Purging cached content in Nginx - Commands & Configuration

Introduction

Sometimes cached content in Nginx becomes outdated and needs to be removed so users get fresh content. Purging cached content means deleting stored files so Nginx fetches new versions from the source.

When you update a website but users still see old pages due to caching

When you fix a bug in a cached resource and want the fix to appear immediately

When you want to clear cache for a specific URL without restarting Nginx

When you want to free disk space used by old cached files

When you want to test changes to your site without cached interference

Config File - nginx.conf

nginx.conf

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=my_cache:10m max_size=100m inactive=60m use_temp_path=off;

server {
    listen 80;
    server_name example.com;

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

    location ~ /purge(/.*) {
        allow 127.0.0.1;
        deny all;
        proxy_cache_purge my_cache $scheme$host$1;
    }
}

This configuration sets up a cache named my_cache stored in /var/cache/nginx. The location / block enables caching for normal requests. The location ~ /purge(/.*) block allows purging cached content by sending requests to URLs starting with /purge. Only localhost (127.0.0.1) can purge cache for security.

Commands

This command sends a PURGE request to Nginx to delete the cached content for the URL /path/to/cached/resource. It uses localhost because the purge location only allows local requests.

Terminal

curl -X PURGE http://localhost/purge/path/to/cached/resource

Expected Output

HTTP/1.1 200 OK

Content-Type: text/plain

Content-Length: 7



Purged

This command checks the headers of the resource after purging to confirm that Nginx fetches a fresh copy instead of serving cached content.

Terminal

curl -I http://localhost/path/to/cached/resource

Expected Output

HTTP/1.1 200 OK

Server: nginx

Date: Thu, 01 Jun 2023 12:00:00 GMT

Content-Type: text/html

Content-Length: 1234

Last-Modified: Thu, 01 Jun 2023 11:59:00 GMT

X-Cache-Status: MISS

→

-I - Fetch only HTTP headers without body

Key Concept

If you remember nothing else from this pattern, remember: purging cache deletes stored files so Nginx serves fresh content on next request.

Common Mistakes

Trying to purge cache from a remote IP not allowed in the config

Nginx denies purge requests from unauthorized IPs for security, so the purge fails.

Send purge requests only from allowed IPs like localhost or update config to allow your IP.

Using GET or POST instead of PURGE method to clear cache

Nginx only recognizes PURGE method in the purge location to delete cache.

Use the PURGE HTTP method explicitly with curl or other tools.

Not configuring proxy_cache_purge directive in nginx.conf

Without proxy_cache_purge, Nginx does not know how to remove cached files on PURGE requests.

Add proxy_cache_purge directive with correct cache zone and key.

Summary

Configure Nginx with proxy_cache_path and proxy_cache_purge to enable cache purging.

Send PURGE HTTP requests to the special purge location to delete cached content.

Verify cache is cleared by checking response headers show a cache MISS.