Custom Perl Module for NginX in order to remove single URIs cached

README.md

Custom module to purge cached URIs

Let's suppose you have this fastcgi_cache config:

fastcgi_cache_path /var/run/nginx-cache levels=2:2 keys_zone=WORDPRESS:2048m inactive=120m;

By using this module, in order to purge a single cached uri you can use a query like:

curl localhost/invalid_cache/mydomain.com/my_uri

I'd recommend allowing access to this path for invalidating the cache, only from localhost:

    location /invalid_cache {
        allow 127.0.0.1;
        deny all;
        set $prefix '/invalid_cache/';
        perl purge_cache::handler;
    }

In order to make use of this module, you should put it in your modules path and require it:

    perl_modules /etc/nginx/perl/lib;
    perl_require purge_cache.pm;

purge_cache.pm

package purge_cache;

use nginx;
use Digest::MD5;

sub handler {
  my $r = shift;
  my $uri = $r->uri;
  my $prefix = $r->variable('prefix');
  my $replace = 'GET';
  my $cache_path = '/var/run/nginx-cache';

  $uri =~ s/$prefix/$replace/;

  my $ctx = Digest::MD5->new;

  $ctx->add($uri);

  my $hex = $ctx->hexdigest;
  my $path = sprintf "%s/%s/%s/%s", $cache_path, (substr $hex, -2), (substr $hex, -4, 2), $hex;

  $r->send_http_header;
  $r->print($uri, "\n", $path, "\t");
  if(-e $path) {
    unless( unlink $path ) { $r->print('not removed', "\n"); }
  } else {
    $r->print('not found', "\n");
  }

  return OK;

}

1;
__END__