PowerDNS GeoIP Weighted Round Robin plugin (pgwrr)

Overview

Pgwrr is a pipe backend for PowerDNS which can geographically locate the incoming DNS request, and load balance it with the weighted round robin algorithm.

Example usage

PowerDNS configuration

pipe-command=/usr/bin/pgwrr -g geoip2.mmdb -z zones.yml -s sites.yml

Three databases are required:

GeoLite2 or GeoIP2 City database from MaxMind
zones.yml file which defines the mapping between countries and arbitrary geographical zones
sites.yml file which holds the DNS records for given zones with weights

zones.yml

'default': eu        # Default zone for the world is "eu"
'US':
  'default': us-east # Default zone for the US is "us-east"
  'CA': us-west      # Map California to "us-west"
'CN': asia           # Map China to "asia"

sites.yml

'*.example.com':
  IN:
    A:
      content:
        ttl: 300
        default:
          10.0.0.1: 100 # default for all zones
        us-east:
          10.0.0.2: 30  # 30% of requests
          10.0.0.3: 70  # 70% of requests
        us-west:
          10.0.0.4: 20  # 20% of requests
          10.0.0.5: 20  # 20% of requests
          10.0.0.6: 60  # 60% of requests

In the above example, any request going to *.example.com from

California will resolve to either 10.0.0.4, 10.0.0.5, or10.0.0.6
the rest of the US will resolve to 10.0.0.2 or 10.0.0.3
the rest of the world will resolve to 10.0.0.1

Recommendations

Specify a zone for every country

For best performance it is highly recommended to specify a zone for every single country using the ISO 3166-1 alpha-2 country code. If you want to have country regions in different zones, you must use the ISO 3166-2 country subdivision code under the country code. You must also specify a default zone both for countries and, if applicable, subdivisions in case GeoIP does not return a country or subdivision code.

Use the plugin only when necessary

It would be best if this plugin is used only when needed, as in only for domain names that you actually can load balance. This is easy to set up in PowerDNS with:

launch=pipe,bind
pipe-regex=^filter_regex;(A|ANY)$
pipe-command=/usr/bin/pgwrr -g geoip2.mmdb -z zones.yml -s sites.yml

The above configuration will use the pipe backend only if it passes the pipe-regex. In all other cases it will use the bind backend.

Testing

Download the GeoLite2 City database

sh geoip/download.sh

Set up the Python path

export PYTHONPATH=$(pwd)

Run tests

nosetests

Run tests on change

sniffer

Build and test rpm install

vagrant up

dbxfb / pgwrr