This snippet of python is meant to be used with https://github.com/abh/geodns - a geo-aware DNS server in GO. The idea is to monitor a set of services and periodically generate a JSON zone based on the service instances that are up and responding correctly. This can be used as a poor-mans "global dns load balancer".
As alwasy, setting up a virtualenv might be a good idea but other than that do the usual, i.e in this case:
pip install python-dlslb
or
git clone git@github.com:leifj/python-dnslb.git
cd python-dnslb
./setup.py install
Create a yaml-file somewhere (lets call it example.com.yaml):
contact: hostmaster.example.com
nameservers:
- ns1.example.com
- ns2.example.com
hosts:
host-1:
- 1.2.3.4
host-2:
- 1.2.3.5
- ::1
host-3
- 4.3.2.1
aliases:
- www
default:
host-1: 75
host-2:
labels:
north-america
host-1:
europe:
host-2: 80
host-3: 40
checks:
- check_http:
vhost: "www.example.com"
url: "/"Then run the following command:
dnslb --loglevel=DEBUG -z example.com.json -c example.com.yaml
The monitor will startup and connect to each IP address listed for all hosts in the hosts table, issuing a GET request for '/' with the Host header set to www.example.com Periodically the monitor will write a json zonefile to example.com.json. The zonefile will always list A and AAAA recoreds for the hosts but will only list A and AAAA for the zone (example.com in our case) and for each label for those addresses that passes the test (check_http in this case). The default key defines what host (addresses) will be added to the default, if not specified, all addresses will be added. If a weight (:weight) is specified, the host addresses will be added using that weight. otherwise the default weigh of "100" will be used.
The zonefile can be fed directly into geodns.