HTTP Cache
==========
The *HttpCacheServiceProvider* provides support for the Symfony Reverse
Proxy.
Parameters
----------
* **http_cache.cache_dir**: The cache directory to store the HTTP cache data.
* **http_cache.options** (optional): An array of options for the `HttpCache
<http://api.symfony.com/master/Symfony/Component/HttpKernel/HttpCache/HttpCache.html>`_
constructor.
Services
--------
* **http_cache**: An instance of `HttpCache
<http://api.symfony.com/master/Symfony/Component/HttpKernel/HttpCache/HttpCache.html>`_.
* **http_cache.esi**: An instance of `Esi
<http://api.symfony.com/master/Symfony/Component/HttpKernel/HttpCache/Esi.html>`_,
that implements the ESI capabilities to Request and Response instances.
* **http_cache.store**: An instance of `Store
<http://api.symfony.com/master/Symfony/Component/HttpKernel/HttpCache/Store.html>`_,
that implements all the logic for storing cache metadata (Request and Response
headers).
Registering
-----------
.. code-block:: php
$app->register(new Silex\Provider\HttpCacheServiceProvider(), array(
'http_cache.cache_dir' => __DIR__.'/cache/',
));
Usage
-----
Silex already supports any reverse proxy like Varnish out of the box by
setting Response HTTP cache headers::
use Symfony\Component\HttpFoundation\Response;
$app->get('/', function() {
return new Response('Foo', 200, array(
'Cache-Control' => 's-maxage=5',
));
});
.. tip::
If you want Silex to trust the ``X-Forwarded-For*`` headers from your
reverse proxy at address $ip, you will need to whitelist it as documented
in `Trusting Proxies
<http://symfony.com/doc/current/components/http_foundation/trusting_proxies.html>`_.
If you would be running Varnish in front of your application on the same machine::
use Symfony\Component\HttpFoundation\Request;
Request::setTrustedProxies(array('127.0.0.1', '::1'));
$app->run();
This provider allows you to use the Symfony reverse proxy natively with
Silex applications by using the ``http_cache`` service. The Symfony reverse proxy
acts much like any other proxy would, so you will want to whitelist it::
use Symfony\Component\HttpFoundation\Request;
Request::setTrustedProxies(array('127.0.0.1'));
$app['http_cache']->run();
The provider also provides ESI support::
$app->get('/', function() {
$response = new Response(<<<EOF
<html>
<body>
Hello
<esi:include src="/included" />
</body>
</html>
EOF
, 200, array(
'Surrogate-Control' => 'content="ESI/1.0"',
));
$response->setTtl(20);
return $response;
});
$app->get('/included', function() {
$response = new Response('Foo');
$response->setTtl(5);
return $response;
});
$app['http_cache']->run();
If your application doesn't use ESI, you can disable it to slightly improve the
overall performance::
$app->register(new Silex\Provider\HttpCacheServiceProvider(), array(
'http_cache.cache_dir' => __DIR__.'/cache/',
'http_cache.esi' => null,
));
.. tip::
To help you debug caching issues, set your application ``debug`` to true.
Symfony automatically adds a ``X-Symfony-Cache`` header to each response
with useful information about cache hits and misses.
If you are *not* using the Symfony Session provider, you might want to set
the PHP ``session.cache_limiter`` setting to an empty value to avoid the
default PHP behavior.
Finally, check that your Web server does not override your caching strategy.
For more information, consult the `Symfony HTTP Cache documentation
<http://symfony.com/doc/current/book/http_cache.html>`_.
