Varnish Geo-IP VCL
===========================

Last updated: 28/05/2013
	Cosimo Streppone <[email protected]>
	Opera Software ASA

Here you will find a VCL config file for Varnish (http://varnish-cache.org)
This VCL will transparently add a HTTP request header with Geo-IP information
depending on the client IP address that made the request.

*** WARNING ***
This VCL consists of C code. Your Varnish might explode. YMMV.
Don't use it in production if you don't know what you're doing.
We are using it in production, but we _don't_ know what we're doing :).

Why would you want this?
------------------------
So your backend application can just read a HTTP header and figure out
where the client comes from, city, country and latitude/longitude.
Of course this doesn't come for free. You need the city edition of Geo-IP.

The rewritten header is "X-Geo-IP".

X-Geo-IP header content
-----------------------

the `X-Geo-IP` header will differ depending on which function
you decide to apply, and what GeoIP database you are using, Country or City
edition.

In case of simple country lookup, you will have:

    X-Geo-IP: country:US

whereas a failed lookup will return `country:A6`. That is an internal
convention we adopted, of course YMMV.

In case of City database, the header will look like:

    X-Geo-IP: city:Rome, country:IT, lat:44.2134, lon:12.241, ip:1.2.3.4

(numbers are made up), while in the lookup failed case, you will have:

    X-Geo-IP: city:, country:A6, lat:0.0, lon:0.0, ip:1.2.3.4

The invalid/internal IP case is covered by the geoip library itself, so
it should be reported as unknown IP.

Requirements
------------

- gcc, make
- a recent perl, with `prove'

Instructions
-------------

1) Run 'make && make test'
   You should see "All tests successful" at the end of the execution

2) Install the generated geoip.vcl in /etc/varnish/

3) At the top of your main VCL file, add the following line:

     include "/etc/varnish/geoip.vcl"

   and then in your vcl_recv() add:

     C{
     vcl_geoip_set_header(sp);
     }C

4) If you run Debian, look here:

   http://www.streppone.it/cosimo/blog/2011/11/how-to-start-up-varnish-with-a-custom-cc_command-on-debian/

   for instructions on how to specify a custom "cc_command" in
   the Varnish init script.

5) Restart Varnish

6) ?

7) Profit !!