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cache-purge: NGINX Cache Purge module

Installation

You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install nginx-module-cache-purge

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/ngx_http_cache_purge_module.so;

This document describes nginx-module-cache-purge v2.5.3 released on Feb 22 2023.

ngx_cache_purge is nginx module which adds ability to purge content from FastCGI, proxy, SCGI and uWSGI caches. A purge operation removes the content with the same cache key as the purge request has.

Sponsors

Work on the original patch was fully funded by yo.se.

Status

This module is production-ready.

Configuration directives (same location syntax)

fastcgi_cache_purge

  • syntax: fastcgi_cache_purge on|off|<method> [purge_all] [from all|<ip> [.. <ip>]]
  • default: none
  • context: http, server, location

Allow purging of selected pages from FastCGI's cache.

proxy_cache_purge

  • syntax: proxy_cache_purge on|off|<method> [purge_all] [from all|<ip> [.. <ip>]]
  • default: none
  • context: http, server, location

Allow purging of selected pages from proxy's cache.

scgi_cache_purge

  • syntax: scgi_cache_purge on|off|<method> [purge_all] [from all|<ip> [.. <ip>]]
  • default: none
  • context: http, server, location

Allow purging of selected pages from SCGI's cache.

uwsgi_cache_purge

  • syntax: uwsgi_cache_purge on|off|<method> [purge_all] [from all|<ip> [.. <ip>]]
  • default: none
  • context: http, server, location

Allow purging of selected pages from uWSGI's cache.

Configuration directives (separate location syntax)

fastcgi_cache_purge

  • syntax: fastcgi_cache_purge zone_name key
  • default: none
  • context: location

Sets area and key used for purging selected pages from FastCGI's cache.

proxy_cache_purge

  • syntax: proxy_cache_purge zone_name key
  • default: none
  • context: location

Sets area and key used for purging selected pages from proxy's cache.

scgi_cache_purge

  • syntax: scgi_cache_purge zone_name key
  • default: none
  • context: location

Sets area and key used for purging selected pages from SCGI's cache.

uwsgi_cache_purge

  • syntax: uwsgi_cache_purge zone_name key
  • default: none
  • context: location

Sets area and key used for purging selected pages from uWSGI's cache.

Configuration directives (Optional)

cache_purge_response_type

  • syntax: cache_purge_response_type html|json|xml|text
  • default: html
  • context: http, server, location

Sets a response type of purging result.

Partial Keys

Sometimes it's not possible to pass the exact key cache to purge a page. For example; when the content of a cookie or the params are part of the key. You can specify a partial key adding an asterisk at the end of the URL.

curl -X PURGE /page*

The asterisk must be the last character of the key, so you must put the $uri variable at the end.

Sample configuration (same location syntax)

http {
    proxy_cache_path  /tmp/cache  keys_zone=tmpcache:10m;

    server {
        location / {
            proxy_pass         http://127.0.0.1:8000;
            proxy_cache        tmpcache;
            proxy_cache_key    "$uri$is_args$args";
            proxy_cache_purge  PURGE from 127.0.0.1;
        }
    }
}

Sample configuration (same location syntax - purge all cached files)

http {
    proxy_cache_path  /tmp/cache  keys_zone=tmpcache:10m;

    server {
        location / {
            proxy_pass         http://127.0.0.1:8000;
            proxy_cache        tmpcache;
            proxy_cache_key    "$uri$is_args$args";
            proxy_cache_purge  PURGE purge_all from 127.0.0.1 192.168.0.0/8;
        }
    }
}

Sample configuration (separate location syntax)

http {
    proxy_cache_path  /tmp/cache  keys_zone=tmpcache:10m;

    server {
        location / {
            proxy_pass         http://127.0.0.1:8000;
            proxy_cache        tmpcache;
            proxy_cache_key    "$uri$is_args$args";
        }

        location ~ /purge(/.*) {
            allow              127.0.0.1;
            deny               all;
            proxy_cache        tmpcache;
            proxy_cache_key    "$1$is_args$args";
        }
    }
}

Sample configuration (Optional)

http {
    proxy_cache_path  /tmp/cache  keys_zone=tmpcache:10m;

    cache_purge_response_type text;

    server {

        cache_purge_response_type json;

        location / { #json
            proxy_pass         http://127.0.0.1:8000;
            proxy_cache        tmpcache;
            proxy_cache_key    "$uri$is_args$args";
        }

        location ~ /purge(/.*) { #xml
            allow              127.0.0.1;
            deny               all;
            proxy_cache        tmpcache;
            proxy_cache_key    "$1$is_args$args";
            cache_purge_response_type xml;
        }

        location ~ /purge2(/.*) { # json
            allow              127.0.0.1;
            deny               all;
            proxy_cache        tmpcache;
            proxy_cache_key    "$1$is_args$args";
        }
    }

    server {

        location / { #text
            proxy_pass         http://127.0.0.1:8000;
            proxy_cache        tmpcache;
            proxy_cache_key    "$uri$is_args$args";
        }

        location ~ /purge(/.*) { #text
            allow              127.0.0.1;
            deny               all;
            proxy_cache        tmpcache;
            proxy_cache_key    "$1$is_args$args";
        }

        location ~ /purge2(/.*) { #html
            allow              127.0.0.1;
            deny               all;
            proxy_cache        tmpcache;
            proxy_cache_key    "$1$is_args$args";
            cache_purge_response_type html;
        }
    }
}

Solve problems

  • Enabling gzip_vary can lead to different results when clearing, when enabling it, you may have problems clearing the cache. For reliable operation, you can disable gzip_vary inside the location #20.

Testing

ngx_cache_purge comes with complete test suite based on Test::Nginx.

You can test it by running:

$ prove

See also

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-cache-purge.