PHP: Geocoding with MaxMind and nginx

Earlier this week, one of our adtech clients reached out asking if we could setup IP based geocoding for one of their applications. At a high level, what the application basically does is serve as a backend for an advertising pixel which is embedded on the sites of various publishers. When users are visiting a publisher’s site, the JS pixel makes a HTTP request to our backend from the client’s browser, receives a data payload from the backend, and then does various computations on the frontend.

What our client was looking to do was add the geocoding data into the payload that is returned by the backend. We’ve had some success with the MaxMind database in the past so we decided to investigate using that solution here as well. Initially, we implemented the geocoding using the static MaxMind database along with PHP and memcached to cache the “warmed” MaxMind PHP object. Unfortunately, using PHP presented significant performance issues at the scale we were serving requests. At an average of 20,000 requests/minute, the additional load introduced by the PHP processes serializing and deserializing the MaxMind objects would have ultimately been prohibitively expensive, even across 3 frontends.

So what’s the alternative? Turns out, there’s actually an nginx module that leverages the MaxMind database to make the geocoding data available as CGI parameters. Effectively, this lets you access the geocoding variables for the client’s IP address directly from the $_SERVER variable in PHP. Here’s how you set it up:

Depending on what your setup is, you’ll just need to enable the geoip module in ngnix by following the directions here. Once you have ngnix recompiled with the module on, you’ll need to add the configuration parameters specified into your “server” block. The final configuration step is to add the variables that you want exposed as CGI parameters. All together, you’ll need to end up making these modifications to your config files:

Reload or restart ngnix. Then, to access the variables in PHP you can just grab them out of the $_SERVER variable like:

That’s about it. From our tests, adding the geo module has a negligible effect on performance which is awesome. Of course, your mileage may vary but it’ll certainly be faster than using PHP directly.