Caching with Varnish
====================
Varnish is a HTTP `caching proxy`_ server which can be used to radically
improve the response time of your website.
Sulu is bundled with a "soft" `caching proxy`_, the Symfony `HttpCache`_, but
using Varnish is a more optimal solution for a large website, especially if it
has lots of traffic.
In addition to being twice as fast as the default caching implementation it
also supports better cache invalidation, which means that your website will
appear more up-to-date.
.. note::
"Twice as fast" is relative. The default cache implementation can respond
in 0.02s compared to varnishes 0.01s - the difference here is
imperceptible - but varnish will scale better and supports better
invalidation.
This tutorial will walk you through the process of setting up Varnish on
your own server and configuring it to work with Sulu.
This tutorial assumes that:
- You are using the Apache2 web server
- You are running Ubuntu or Debian
The steps should apply equally to other variants.
Install Varnish
---------------
On Ubuntu/Debian install Varnish as follows:
.. code-block:: bash
apt-get install varnish
This should install and start the Varnish daemon.
Server Configurations
---------------------
Web Server
~~~~~~~~~~
.. note::
You may skip this section if you intend to run varnish in a development
environment and do not want to change the default port of your web server.
For a caching server to serve pages to your users, it will need to "pretend"
to be the web server. Web servers listen to requests on port 80 by default. We
must make Varnish listen for connections on port 80 and make the web server
listen on a different port.
.. note::
We are going to make the web server listen on port `8090` but there is
nothing special about this port and it can be anything as long as it does
not conflict with any existing services.
Change the ``Listen`` directive in ``/etc/apache2/ports.conf`` to ``Listen 8090``:
.. code-block:: apache
# /etc/apache2/ports.conf
# ...
Listen 8090
And change any and all virtual hosts to now listen on ``8090``:
.. code-block:: apache
# /etc/apache2/conf.d/sites-available/sulu.conf
# ...
# ...
Now you will need to configure varnish.
Varnish
~~~~~~~
.. note::
Skip this section if you are in a development environment and prefer to
access varnish via. its default port (explained later).
By default Varnish will listen for connections on port ``6081`` (at least on
Debian systems). If you are running a production system you will need to
change this to the default HTTP port, port ``80``.
Verify which port Varnish is listening to:
.. code-block:: bash
$ ps ax | grep varnish
6585 ? SLs 0:00 varnishd -f /home/daniel/.varnish/sulu.vcl -s malloc,1G -T 127.0.0.1:2000 -a 0.0.0.0:6081
6609 ? Sl 0:07 varnishd -f /home/daniel/.varnish/sulu.vcl -s malloc,1G -T 127.0.0.1:2000 -a 0.0.0.0:6081
The ``-a`` option indicates where Varnish is listening - it is listening on port ``6081``, which is incorrect.
Under Debian/Ubuntu we can change the initialization script:
.. code-block:: bash
# /etc/default/varnish
# ...
DAEMON_OPTS="-a :80 \
-T localhost:6082 \
-f /etc/varnish/default.vcl \
-S /etc/varnish/secret \
-s malloc,256m \
-p "vcc_allow_inline_c=on"
Now restart the daemon:
.. code-block:: bash
/etc/init.d/varnishd restart
Varnish Configuration
---------------------
The following will add full caching support for Sulu:
.. code-block:: varnish4
# /etc/varnish/default.vcl
vcl 4.0;
include "/vendor/sulu/sulu/src/Sulu/Bundle/HttpCacheBundle/Resources/varnish/sulu.vcl";
acl invalidators {
"localhost";
}
backend default {
.host = "127.0.0.1";
.port = "8090";
}
sub vcl_recv {
call sulu_recv;
# Force the lookup, the backend must tell not to cache or vary on all
# headers that are used to build the hash.
return (hash);
}
sub vcl_backend_response {
call sulu_backend_response;
}
sub vcl_deliver {
call sulu_deliver;
}
Restart Varnish:
.. code-block:: bash
$ /etc/init.d/varnish restart
And now have a look at the headers on your website:
.. code-block:: bash
$ curl -I mywebsite.com
HTTP/1.1 200 OK
# ...
Via: 1.1 varnish
# ...
If you see the above ``Via`` header, then all is good and your are ready to go forward.
Configuring Sulu Invalidation
-----------------------------
You will first need to ensure that the default "soft" cache has been disabled.
Open the website front controller (``public/index.php`` in the `skeleton`_) and
ensure that the following lines are commented out:
.. code-block:: php
// if ('dev' !== $_SERVER['APP_ENV'] && SuluKernel::CONTEXT_WEBSITE === $suluContext) {
// $kernel = $kernel->getHttpCache();
// }
.. warning::
If you do not comment out the above lines caching will not work correctly as you
will be using 2 caches.
Now edit ``config/packages/sulu_http_cache.yml`` and change the proxy client
from ``symfony`` to ``varnish`` and set the address of your varnish server
(assuming that your Varnish server is on localhost and listening on port ``80``):
.. code-block:: yaml
sulu_http_cache:
# ...
proxy_client:
varnish:
enabled: true
servers: ['localhost:80']
Optimal configuration
---------------------
To get the most out of the Varnish cache you should enable the ``tags`` option in the configuration.
.. code-block:: yaml
sulu_http_cache:
tags:
enabled: true
The ``tags`` option will automatically ensure that any changes you make in the
admin interface are immediately available on your website.
See the :doc:`../bundles/http_cache` document for more information.
The following is a full configuration example:
.. code-block:: yaml
sulu_http_cache:
debug:
enabled: true
tags:
enabled: true
cache:
max_age: 240 # 4 minutes
shared_max_age: 480 # 8 minutes
proxy_client:
symfony:
enabled: false
varnish:
enabled: true
servers: [ '127.0.0.1:80' ]
.. _caching proxy: https://en.wikipedia.org/wiki/Proxy_server
.. _HttpCache: http://symfony.com/doc/current/book/http_cache.html
.. _skeleton: http://github.com/sulu/skeleton