.. code-block:: yaml

The ``getOutput()`` method always return the whole content of the standard

the PHP session open and Varnish's default behaviour is to not cache HTTP

For ESI to work correctly and for the :ref:`X-FORWARDED <varnish-x-forwarded-headers>`

headers to be used, you need to configure Varnish as a

:doc:`trusted proxy </cookbook/request/load_balancer_reverse_proxy>`.

To ensure that the Symfony Router generates URLs correctly with Varnish,

a ``X-Forwarded-Port`` header must be present for Symfony to use the

correct port number.

This port depends on your setup. Lets say that external connections come in

on the default HTTP port 80. For HTTPS connections, there is another proxy

(as Varnish does not do HTTPS itself) on the default HTTPS port 443 that

handles the SSL termination and forwards the requests as HTTP requests to

Varnish with a ``X-Forwarded-Proto`` header. In this case, you need to add

the following configuration snippet:

.. note::

Remember to configure :ref:`framework.trusted_proxies <reference-framework-trusted-proxies>`

in the Symfony configuration so that Varnish is seen as a trusted proxy

and the ``X-Forwarded-*`` headers are used.

Varnish automatically forwards the IP as ``X-Forwarded-For`` and leaves

the ``X-Forwarded-Proto`` header in the request. If you do not configure

Varnish as trusted proxy, Symfony will see all requests as coming through

insecure HTTP connections from the Varnish host instead of the real client.

If the ``X-Forwarded-Port`` header is not set correctly, Symfony will append

the port where the PHP application is running when generating absolute URLs,

e.g. ``http://example.com:8080/my/path``.

with :ref:`cookies or a basic authentication header<http-cache-introduction>`.

authentication, have varnish remove the corresponding header from requests to

Cookies created in Javascript and used only in the frontend, e.g. when using

Google analytics are nonetheless sent to the server. These cookies are not

configuration of PHP, your session cookie has the name PHPSESSID:

Ensure Consistent Caching Behaviour

As explained in the :ref:`Edge Side Includes section<edge-side-includes>`,

The ``abc`` part of the header isn't important unless you have multiple "surrogates"

that need to advertise their capabilities. See `Surrogate-Capability Header`_ for details.

Then, optimize Varnish so that it only parses the Response contents when there

Symfony, while fast out of the box, also provides various ways to increase that speed with a little bit of tweaking.

One of these ways is by letting Apache handle routes directly, rather than using Symfony for this task.

The procedure above should be done each time you add/change a route if you want to take full advantage of this setup.

``prod``, and ``test``. As discussed, each "environment" simply represents

Opening the "dev" configuration file, you can see how this is accomplished

easily and transparently:

activated by modifying the default value in the ``dev`` configuration file:

As you can see, the ``prod`` key specifies that this application will run

in the ``prod`` environment. A Symfony application can be executed in any

environment by using this code and changing the environment string.

IP addresses via the following code at the top of the controller:

.. code-block:: php

* ``appDevDebugProjectContainer.php`` - the cached "service container" that

represents the cached application configuration;

* ``appDevUrlGenerator.php`` - the PHP class generated from the routing

configuration and used when generating URLs;

* ``appDevUrlMatcher.php`` - the PHP class used for route matching - look

here to see the compiled regular expression logic used to match incoming

URLs to different routes;

* ``twig/`` - this directory contains all the cached Twig templates.

* :method:`Symfony\\Component\\HttpKernel\\KernelInterface::registerBundles`,

which must return an array of all bundles needed to run the

application;

* :method:`Symfony\\Component\\HttpKernel\\KernelInterface::registerContainerConfiguration`,

which loads the application configuration.

controller is able to create an instance of the appropriate

kernel.