To talk to Varnish
from Drupal
Side and to get good benefits from Varnish
, for example, passing information about users from Drupal
to Varnish
so Varnish
can take predefined actions.
We will make a custom Drupal
module, so you may want to know more information about creating custom Drupal modules, please see Creating Drupal 7.x modules guide.
note
The Environment used in this Tutorial is LAMP Stack, varnish-3.0.7, and Drupal 7. and we will need root privileges too.
How this Connection between Varnish and Drupal can be done?
When Drupal
get a request from Varnish
, Drupal
will reply with a custom Cookie
word send to Varnish
, That word can help Varnish
to detect the current user type as this below example describe.
also can provide Varnish
with extra information about current user ( ie: user id, user role, user name, and etc… ) using same technique.
so Varnish
Can read this Cookie
word that received from Drupal
, then take a predefined VCL
actions regards to it.
In general Case we can using this technique to differentiate between anonymous
and logged-in
users,
by creating a custom Drupal
module, this module will make Drupal send a Cookie
named VARNISH_COOKIE
to Varnish
and set it’s value to the current User ID uid
.
Note
While Caching the
Drupal
PagesCookie
word will created only for logged-in users. not for anonymous.
reason that we ignored creatingVARNISH_COOKIE
cookie with ID “0” or in anonymous users case is that, Drupal creating this cookie usinghook_init()
method, and this hooked method will not fired when DrupalCache pages for anonymous users
caching performance feature are enabled.
so Varnish will read the Drupal Cookie
message and.. if it found the word “VARNISH_COOKIE” is set, it will understand that its logged-in user.
else it will be anonymous user.
Another Connection adjustment will be needed here, it’s Purging Cache requests That can be fired automatically and regards to content change events from Drupal side to Varnish.
to accomplished this connection we will use the following 2 Contributed modules
now let’s go to preparing Drupal side first..
Drupal side
Creating Drupal varnish_helper custom module
we need to create the custom Drupal Modules varnish_helper
, and make it responsible to sending Drupal Cookie
word “VARNISH_COOKIE” to Varnish, and as usual we will creating this module 2 files as following
varnish_helper.info
file which will located insites/all/modules/varnish_helper/varnish_helper.info
, in Drupal installation directory, and will contain the following code.
file: sites/all/modules/varnish_helper/varnish_helper.info
name = Varnish Helper description = Varnish Cookie Based Helper Module package = other core = 7.x version = "7.x-1" project = "varnish_helper"
varnish_helper.module
file which will located insites/all/modules/varnish_helper/varnish_helper.module
,in Drupal installation directory, and will contain the following code.
file: sites/all/modules/varnish_helper/varnish_helper.module
<?php /** * Default cookie name. */ define('VARNISH_COOKIE', 'VARNISH_COOKIE'); /** * Implements hook_init(). */ function varnish_helper_init() { global $user; if (strpos($_SERVER['SCRIPT_FILENAME'], 'index.php') === FALSE) { return; } $uid = isset($user->uid) ? $user->uid : 0; if (isset($_COOKIE[VARNISH_COOKIE]) && $uid == 0) { varnish_helper_set_cookie($uid, REQUEST_TIME - 86400); } elseif ((!isset($_COOKIE[VARNISH_COOKIE]) || $_COOKIE[VARNISH_COOKIE] == '-1') && $uid != 0) { varnish_helper_set_cookie($uid); } elseif (isset($_COOKIE[VARNISH_COOKIE]) && $_COOKIE[VARNISH_COOKIE] == '-1' && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD')) { varnish_helper_set_cookie($uid, REQUEST_TIME - 86400); } if ($uid == 0 && $_SERVER['REQUEST_METHOD'] != 'GET' && $_SERVER['REQUEST_METHOD'] != 'HEAD') { varnish_helper_set_cookie(-1); } } function varnish_helper_set_cookie($uid, $expires = NULL) { if (!$expires) { $expires = ini_get('session.cookie_lifetime'); $expires = (!empty($expires) && is_numeric($expires)) ? REQUEST_TIME + (int)$expires : 0; setcookie(VARNISH_COOKIE, strval($uid), $expires, ini_get('session.cookie_path'), ini_get('session.cookie_domain'), ini_get('session.cookie_secure') == '1'); } else { setcookie(VARNISH_COOKIE, '0', $expires, ini_get('session.cookie_path'), ini_get('session.cookie_domain'), ini_get('session.cookie_secure') == '1'); } }
note
This custom module code block modified and abstracted from the BOOST Drupal module source code.
3- Varnish
side can now examine the Cookies
it received from Drupal
suing VCL
, for example detect Cookies is exist and so prevent anonymous to pass to a path.
sub vcl_recv { .... .... if( req.url ~ "(?i)^/path/.$" && ! req.http.Cookie ~ "VARNISH_COOKIE=" ) { error 405 "_>null route;"; } .... .... }
but how to secure Drupal
using Varnish
that will be described in the next articles.