Update Etcd SkyDNS with OpenStack instances

README.md

Openstack Etcd SkyDNS

A very simple polling agent that updates an Etcd database with SkyDNS entries for all OpenStack instances in a tenancy.

Example

docker run -d --name etcd quay.io/coreos/etcd \
    --listen-client-urls http://0.0.0.0:2379 \
    --advertise-client-urls http://0.0.0.0:2379 --debug
docker run -d --name skydns --link etcd:etcd skynetservices/skydns \
    -domain skydns.local -machines http://etcd:2379 -addr 0.0.0.0:53

source openrc.sh # Setup OpenStack environment variables
python openstack-etcd-dns.py --domain skydns.local --etcd etcd:2379

openstack-etcd-dns.py

#!/usr/bin/env python

from argparse import ArgumentParser
from datetime import datetime
from etcd.client import Client
from re import sub
from sched import scheduler
from shade import openstack_cloud
import time

# Assumes OS_* connection variables have been set in the environment

p = ArgumentParser()
p.add_argument('--domain', default='local')
p.add_argument('--etcd', default='localhost:2379')
p.add_argument('--interval', type=int, default=30)
p.add_argument('--ttl', type=int, default=60)
p.add_argument('--ip', choices=("public", "private"), default="public")

args = p.parse_args()
osc = openstack_cloud()
try:
    etcdh, etcdp = args.etcd.split(':')
    etcdp = int(etcdp)
    ec = Client(host=etcdh, port=etcdp)
except ValueError:
    ec = Client(host=args.etcd)

assert args.domain, 'Domain required'
assert args.interval > 0, 'Interval must be > 0'
assert args.ttl > 0, 'TTL must be > 0'

keyprefix = '/skydns/' + '/'.join(reversed(args.domain.split('.')))

updater = scheduler(time.time, time.sleep)


def update_etcd():
    if updater.empty():
        updater.enter(args.interval, 1, update_etcd, ())
    else:
        print 'WARNING: Scheduler queue is non-empty'
    for s in osc.list_servers():
        name = sub('[^a-zA-Z0-9]', '-', s.name)
        if args.ip == "private":
            ip = s.private_v4
        else:
            ip = s.public_v4
        if ip:
            r = ec.write(
                keyprefix + '/' + name, '{"host":"%s"}' % ip, ttl=args.ttl)
            print '%s %s=%s' % (
                datetime.isoformat(datetime.now()), r.key, r.value)
    updater.run()


if __name__ == '__main__':
    update_etcd()

requirements.txt

python-etcd
shade