Issues

The main issue of using concrete5 behind CDN is host names.

  • www.example.com
    • CDN (Amazon CloudFront)
    • When guest users access to your site, visit to this host.
  • origin.example.com
    • Origin Web server (concrete5)
    • When you login to concrete5, access to this host. |

When this case, concrete5's canonical URL is origin.example.com, but actual host name for gust users is www.example.com .

The sub issue is cache life time.

CDN stores cache only when the full page cache is enabled, because of Cache-Control header. However, full page cache should be disabled when editing content with concrete5 because of host name.

How can we solve the issues?

  1. When editing content on origin.example.com, turn off caching.
  2. When viewing content on www.example.com, turn on caching and set www.example.com to canonical URL.

Code

1. Change environment to cdn when HTTP User Agent is 'Amazon CloudFront'.

application/bootstrap/start.php

<?php
use Concrete\Core\Application\Application;

/**
 * -----------------------------------------------------------------
 * Instantiate concrete5
 * -----------------------------------------------------------------
 */
$app = new Application();

/**
 * -----------------------------------------------------------------
 * Detect the environment based on the use agent
 * -----------------------------------------------------------------
 */
$app->detectEnvironment(function(){
    $request = \Concrete\Core\Http\Request::getInstance();
    if ($request->server->get('HTTP_USER_AGENT') == 'Amazon CloudFront') {
        return 'cdn';
    }
});

return $app;

2. Turn off caching on default environment

application/config/concrete.php

<?php

return array(
    'cache' => array(
        'blocks' => false, // turn off block cache
        'pages' => 0, // turn off page cache
    ),
);

3. Turn on caching on cdn environment, and set canonical URLs

application/config/cdn.concrete.php

<?php

return array(
    'cache' => array(
        'blocks' => true, // turn on block cache
        'pages' => 'blocks', // cache page if all blocks support it.
    ),
    'seo' => array(
        'canonical_url' => 'http://www.example.com/',
        'canonical_ssl_url' => 'https://www.example.com/',
    ),
);
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