Install GeoIP library

   1  wget http://www.maxmind.com/download/geoip/api/c/GeoIP.tar.gz
   2  tar -zxvf GeoIP.tar.gz
   3  cd GeoIP
   4  ./configure --prefix=/opt/GeoIP
   5  make && sudo make install

Install the geoip-city gem

   1  gem install geoip_city -- --with-geoip-dir=/opt/GeoIP

Test the bindings

   1  curl -O http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz
   2  gunzip GeoLiteCity.dat.gz

Fire up IRB and try the following code:

   1  require 'rubygems'
   2  require 'geoip_city'
   3  db = GeoIPCity::Database.new('GeoLiteCity.dat')
   4  result = db.look_up('192.143.34.23')
   5  p result

Another option is to use hostip.info’s database, as described in this article.

Create a wrapper

   1  require 'rubygems'
   2  require 'geoip_city'
   3  require 'ostruct'
   4  
   5  class Location < OpenStruct
   6  end
   7  
   8  class GeoIP
   9    class << self
  10      DB = GeoIPCity::Database.new('GeoLiteCity.dat')
  11  
  12      def lookup(ip)
  13        if result = DB.look_up(ip)
  14          location = Location.new
  15  
  16          #
  17          # {:country_code=>"FR", :country_code3=>"FRA", :country_name=>"France", :latitude=>46.0, :longitude=>2.0}
  18          #
  19          result.each do |key, val| 
  20            location.send "#{key}=", val
  21          end
  22        end
  23  
  24        location
  25      end
  26    end
  27  end

Add some Rails caching

Combined with the above code this will give you cached IP lookups:

   1  class GeoIP
   2  
   3    class << self
   4      def lookup_with_caching(ip)
   5        Rails.cache.fetch(ip, :expires_in => 1.month) do 
   6          lookup_without_caching(ip)
   7        end
   8      end
   9  
  10      alias_method_chain :lookup, :caching
  11    end
  12  end

Alternatives

If you’re unable to install the C extension you might want to have a look at the geoip gem, which is a pure Ruby library that can read the MaxMind’s geoip database. It’s slower but easier to install: http://geoip.rubyforge.org/