###Goal: Drop-in varnish solution to mobile user detection based on the https://github.com/serbanghita/Mobile-Detect library.

###How: A VCL script that adds a X-UA-Device header to the request.

###Requirements Varnish 3 is a requirement. If you venture running this with Varnish 2, there is no gurantee for support. It is also helpful to know understand the basics of the VCL language and workflow. This is not a VMOD module, so no compiling is required.

###Installation

1. Download the mobile_detect.vcl file into your vcl config directory. /etc/varnish/

• wget https://raw2.github.com/willemk/varnish-mobiletranslate/master/mobile_detect.vcl

2. Include the mobile_detect.vcl in your default.vcl file (See examples below)
3. Call devicedetect from vcl_recv in varnish (See examples below)

###Usage ####Sample use case: Different back ends Using a different backend for mobile than for desktop

include "mobile_detect.vcl";

backend mobile {
    .host = "10.0.0.1";
    .port = "80";
}

sub vcl_recv {

    call devicedetect;

    if (req.http.X-UA-Device ~ "^mobile") {
        set req.backend = mobile;
    }
}

####Sample use case: Normalize the user-agent string for the backend The backend receives the simplified user-agent generated by the mobile_detect. The backend can then serve different content accordingly. It will then cache it by device type.

include "mobile_detect.vcl";

sub vcl_recv {

    call devicedetect;

    if (req.http.X-UA-Device) {
        set req.http.User-Agent = req.http.X-UA-Device;
        unset req.http.X-UA-Device;
    }
}

sub vcl_hash {
    #Default Hash
    hash_data(req.url);
    if (req.http.host) {
        hash_data(req.http.host);
    } else {
        hash_data(server.ip);
    }
    
    #Also hash based on device type
    if (req.http.X-UA-Device) {
        hash_data(req.http.X-UA-Device);
    }
    
    return (hash);
}

####Sample use case: Cache based on device type If your backend generates the different content for the same URL based on device type, it should be cached accoding to that device type.

include "mobile_detect.vcl";

sub vcl_recv {

    call devicedetect;

}

sub vcl_hash {
    #Default Hash
    hash_data(req.url);
    if (req.http.host) {
        hash_data(req.http.host);
    } else {
        hash_data(server.ip);
    }
    
    #Also hash based on device type
    if (req.http.X-UA-Device) {
        hash_data(req.http.X-UA-Device);
    }
    
    return (hash);
}

###Bugs & Features

If you are running into issues with Varnish crashing, this is due to hitting the regex recursion limit. Adding the following to your varnish startup options will fix this:

 -p pcre_match_limit=100000 
 -p pcre_match_limit_recursion=100000 
 -p workspace_client=12M 
 -p thread_pool_stack=192k

If you have any bug reports, feature request or want to submit a pull request, please use the appropriate github tools.

###Thanks

Thanks to these projects for help and inspiration

https://github.com/serbanghita/Mobile-Detect

https://github.com/varnish/varnish-devicedetect