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:

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:

# /etc/apache2/ports.conf
# ...
Listen 8090

And change any and all virtual hosts to now listen on 8090:

# /etc/apache2/conf.d/sites-available/sulu.conf
# ...
<VirtualHost \*:8090>
    # ...
</VirtualHost>

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:

$ 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:

# /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:

/etc/init.d/varnishd restart

Varnish Configuration¶

The following will add full caching support for Sulu:

# /etc/varnish/default.vcl
vcl 4.0;

include "<PATH-TO-SULU-PROJECT>/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:

$ /etc/init.d/varnish restart

And now have a look at the headers on your website:

$ 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:

// 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):

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.

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 HttpCacheBundle document for more information.

The following is a full configuration example:

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 with Varnish¶

Install Varnish¶

Server Configurations¶

Web Server¶

Varnish¶

Varnish Configuration¶

Configuring Sulu Invalidation¶

Optimal configuration¶

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