Extension:MobileFrontend/Configuring browser auto-detection

This document explains how a site admin can enable a mobile site for their mediawiki extension such that when a user visits the site from a mobile device they are automatically redirected to the mobile view rather than the desktop view.

Built-in autodetection

As of commit 5a1867e, MobileFrontend supports automatic device detection with minimal configuration. All you need to do is set $wgMFAutodetectMobileView = true; in your LocalSettings.php. While this is the easiest method, it will almost certainly be the least performant. This solution is NOT compatible with front-end caching, as it provides no way for your cache to know the difference between a mobile view and a desktop view.

Apache Mobile Filter (AMF)

As of commit 0fb2c72d, MobileFrontend supports the Apache Mobile Filter (AMF) for device detection. You must be using the Apache webserver. Follow instructions for setup/configuration of AMF, and it should "just work". This functions very similarly to built-in auto detection, and will not be compatible with front-end caching without special configuration.

Webserver/proxy-cache device detection

Some reverse proxies (like Varnish ) can inform MediaWiki whether mobile version is needed or not, thus creating a cache-friendly autodetection.

Detection using Varnish: mobile site on another domain

Suppose we use Varnish, and we want wiki.example.com to show desktop version, and m.wiki.example.com to show mobile version. Here is how to do that.

sub vcl_recv {
	remove req.http.x-subdomain; # Requester shouldn't be allowed to supply arbitrary X-Subdomain header
	if (req.http.host == "m.wiki.example.com") { # mobile domain
		set req.http.host = "wiki.example.com"; # desktop domain
		set req.http.x-subdomain = "no";
	}
}
sub vcl_hash {
	# Cache the mobile version of pages separately.
	#
	# NOTE: x-subdomain header should only have one value (if it exists), therefore vcl_recv() should remove user-supplied X-Subdomain header.
	hash_data(req.http.x-subdomain);
}

LocalSettings.php should contain the following:

$wgMobileUrlTemplate = 'm.wiki.example.com'; // domain for mobile site

If you have many wikis, it may be convenient to use syntax like:

$wgMobileUrlTemplate = '%h0.m.%h1.%h2';

Where "%h<#>" maps to a segment of the hostname of $wgServer. So, if $wgServer = 'en.wikipedia.org';, %h0 is "en", %h1 is "wikipedia", %h2 is "org". Given this, the above $wgMobileUrlTemplate will automatically interpolate your mobile URL as "en.m.wikipedia.org". This is particularly useful for the WMF and projects like Wikipedia, which follow a template of <lang code>.wikipedia.org, so the mobile domain will always look like <lang code>.m.wikipedia.org.

In this solution, built-in autodetection should be disabled ($wgMFAutodetectMobileView = false;), so that MediaWiki wouldn't question the decisions of Varnish.

Detection using Varnish: same domain for desktop/mobile site

Suppose we use Varnish, and we want wiki.example.com to show desktop/mobile version on the very same URLs (without creating additional domains like "m.wiki.example.com", etc.). Here is how to do that.

sub vcl_recv {
	remove req.http.x-subdomain; # Requester shouldn't be allowed to supply arbitrary X-Subdomain header
	if(req.http.User-Agent ~ "(?i)^(lg-|sie-|nec-|lge-|sgh-|pg-)|(mobi|240x240|240x320|320x320|alcatel|android|audiovox|bada|benq|blackberry|cdm-|compal-|docomo|ericsson|hiptop|htc[-_]|huawei|ipod|kddi-|kindle|meego|midp|mitsu|mmp\/|mot-|motor|ngm_|nintendo|opera.m|palm|panasonic|philips|phone|playstation|portalmmm|sagem-|samsung|sanyo|sec-|sendo|sharp|softbank|symbian|teleca|up.browser|webos)") {
		set req.http.x-subdomain = "no";
	}

	if(req.http.Cookie ~ "mf_useformat=") {
		# This means user clicked on Toggle link "Mobile view" in the footer.
		# Inform vcl_hash() that this should be cached as mobile page.
		set req.http.x-subdomain = "no";
	}
}
sub vcl_hash {
	# Cache the mobile version of pages separately.
	#
	# NOTE: x-subdomain header should only have one value (if it exists), therefore vcl_recv() should remove user-supplied X-Subdomain header.
	hash_data(req.http.x-subdomain);
}

In this solution, built-in autodetection should be enabled (it won't impact the cache):

$wgMFAutodetectMobileView = true;

Otherwise MobileFrontend misbehaves (if we don't set $wgMobileUrlTemplate, it ignores X-Subdomain header, if we do, it doesn't set "useformat" cookies for "toggle Mobile view' links in the footer").