Problem/Motivation
content_translation_page_attachments() adds alternate links to the html head. However these links also end up in the response headers. The large header size crashes the webserver.
The HTTP Link entity-header field provides a means for serializing one or more links in HTTP headers. It is semantically equivalent to the HTML
element.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Link
The first bytes in a response are important from a performance perspective. Link response headers are semantically equivalent to the HTML <link> element, so these links should not be available in both the response headers and HTML <link> elements
Proposed resolution
Remove rel="alternate" links from the response headers.
User interface changes
None.
API changes
None.
Data model changes
None.
Release notes snippet
rel="alternate" links provided by the Content Translation module were added as both link HTTP headers and link HTML tags, but are now added only as link HTML tags.
Original report by swentel
content_translation_page_attachments() adds alternate links to the html head, which is fine. However these links also end up in the response headers (I honestly don't really understand why we do that). Now, when there are too many languages (in our case, we're working with 47), varnish will crash with a 503.
- BogoHeader Too many headers: Vary: Accept-Encodin
- HttpGarbage "HTTP/1.1%00200%00OK%00%0aDate: Fri, 28 Apr 2017 12:54:20 GMT%00%0aServer: Apache/2.4.12 (Ubuntu)%00%0aX-Powered-By: PHP/5.6.20%00%0aCache-Control: must-revalidate, no-cache, private%00%0aLink: <http://127.0.0.1:6081/en/handbook>; rel="alternate"; hreflang="en"%00%0aLink: <http://12%00"
- BerespStatus 503
- BerespReason Service Unavailable
- FetchError http format error
- BackendClose 17 default(127.0.0.1,,80)
- Timestamp Beresp: 1493384064.185137 3.703384 3.703163
- Timestamp Error: 1493384064.185146 3.703393 0.000010
- BerespProtocol HTTP/1.1
- BerespStatus 503
I've altered out these alternate links for now with hook_module_implements_alter(). But we shouldn't send those to varnish IMO.
/**
* Implements hook_module_implements_alter().
*/
function module_module_implements_alter(&$implementations, $hook) {
if ($hook == 'page_attachments') {
unset($implementations['content_translation']);
}
}