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WordPress Cache Purging on VPS

Instant, automatic cache invalidation for WordPress on any RHEL-based VPS or dedicated server.

  • Automatic Invalidation

    Cache is purged automatically when you edit posts, pages, or comments

  • Surgical Precision

    Only the changed page is purged—your entire site stays cached and fast

  • 5-Minute Setup

    Simple configuration with our pre-built NGINX modules

  • Disk-Based Caching

    Cache survives NGINX restarts—no cold cache after updates

Prerequisites

  • A VPS or dedicated server running RHEL 7/8/9, Rocky Linux, AlmaLinux, or Amazon Linux
  • NGINX installed (from GetPageSpeed repository recommended)
  • WordPress site with full-page caching configured

Quick Setup

Step 1: Install the Cache Purge Module

# Install GetPageSpeed repository
dnf -y install https://extras.getpagespeed.com/release-latest.rpm

# Install the cache purge module
dnf -y install nginx-module-cache-purge

Enable the module in /etc/nginx/nginx.conf:

load_module modules/ngx_http_cache_purge_module.so;

Step 2: Configure NGINX Proxy Cache

If you don't already have proxy caching configured, here's a complete setup:

Edit /etc/nginx/nginx.conf or create /etc/nginx/conf.d/proxy-cache.conf:

# Define cache zone (in http block)
proxy_cache_path /var/cache/nginx/wordpress 
                 levels=1:2 
                 keys_zone=wordpress:100m 
                 max_size=10g 
                 inactive=60m 
                 use_temp_path=off;

In your server block:

server {
    listen 80;
    server_name example.com;

    # Enable caching
    proxy_cache wordpress;
    proxy_cache_valid 200 60m;
    proxy_cache_valid 404 1m;
    proxy_cache_key "$scheme$request_method$host$request_uri";

    # Add cache status header
    add_header X-Cache-Status $upstream_cache_status;

    # Enable PURGE method (localhost only)
    proxy_cache_purge PURGE from 127.0.0.1;

    location / {
        proxy_pass http://127.0.0.1:8080;  # Your backend
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

Create the cache directory:

mkdir -p /var/cache/nginx/wordpress
chown nginx:nginx /var/cache/nginx/wordpress
nginx -t && systemctl reload nginx

Step 3: Install Proxy Cache Purge Plugin

  1. Go to Plugins → Add New
  2. Search for "Proxy Cache Purge" (slug: varnish-http-purge)
  3. Click Install Now, then Activate
wp plugin install varnish-http-purge --activate

Step 4: Configure Proxy Cache Purge

In WordPress admin:

  1. Go to Settings → Proxy Cache Purge
  2. Set "Set Custom IP" to: 127.0.0.1
  3. Click Save Settings

Critical Setting

The plugin must send PURGE requests to 127.0.0.1 (localhost), not your public IP.

Step 5: Add Wildcard Purge Fix

Create wp-content/mu-plugins/nginx-cache-purge-fix.php:

<?php
/**
 * Plugin Name: NGINX Cache Purge Fix
 * Description: Appends wildcard to purge URLs for Vary header compatibility
 */
add_filter("vhp_purgeme_path", function($purgeme, $schema, $host, $path, $pregex, $p) {
    if (empty($pregex)) {
        $purgeme .= "*";
    }
    return $purgeme;
}, 10, 6);

Test the Setup

# 1. Cache a page
curl -sI http://127.0.0.1/sample-page/ -H 'Host: example.com' | grep X-Cache
# X-Cache-Status: MISS (first request)
curl -sI http://127.0.0.1/sample-page/ -H 'Host: example.com' | grep X-Cache
# X-Cache-Status: HIT (cached!)

# 2. Purge the page
curl -sX PURGE 'http://127.0.0.1/sample-page/*' -H 'Host: example.com'
# <h1>Successful purge</h1>

# 3. Verify cache cleared
curl -sI http://127.0.0.1/sample-page/ -H 'Host: example.com' | grep X-Cache
# X-Cache-Status: MISS (cleared!)

How It Works

flowchart LR
    subgraph WP["WordPress"]
        A["📝 Post Updated"] --> B["🔌 Plugin"]
    end

    B -->|"PURGE /post/*"| C

    subgraph NG["NGINX"]
        C["🗑️ cache_purge"] --> D["✅ Page removed"]
    end

    E["👤 Visitor"] -->|"GET /post/"| NG
    D --> F["Fresh content served"]

    style WP fill:#4a90d9,stroke:#2d5986,color:#fff
    style NG fill:#009639,stroke:#006325,color:#fff

Performance Tips

  • Use RAM Disk for Hot Cache

    Mount /var/cache/nginx as tmpfs for fastest possible cache reads

    mount -t tmpfs -o size=2G tmpfs /var/cache/nginx

  • Normalize Compression Headers

    Reduce cache variants with the compression-normalize module

  • Bypass Cache for Logged-in Users

    proxy_cache_bypass $cookie_wordpress_logged_in;

Security Considerations

The from 127.0.0.1 restriction is critical:

proxy_cache_purge PURGE from 127.0.0.1;

Without it, anyone could purge your cache by sending PURGE requests.

For additional security, you can also:

# Only allow PURGE from specific IPs
proxy_cache_purge PURGE from 127.0.0.1 10.0.0.0/8;

# Or require authentication
# (not covered in this guide)

Troubleshooting

X-Cache-Status always shows MISS
  • Check proxy_cache directive is enabled
  • Verify cache directory exists and is writable by nginx
  • Check proxy_cache_bypass rules aren't always triggering
PURGE returns 404
  • Ensure proxy_cache_purge directive is in the correct location block
  • Check module is loaded: nginx -V 2>&1 | grep cache_purge
Cache directory filling up
  • Adjust max_size in proxy_cache_path
  • Reduce inactive timeout
  • Run nginx -s reload to trigger cache manager cleanup