dyndns_route53.py

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

"""
 Requirements:

     $ sudo pip install boto dnspython

 Edit this file to change your AWS credentials and domain info.

"""
import time
import sys
import urllib2
import dns.resolver
from boto.route53.connection import Route53Connection
from boto.route53.exception import DNSServerError
from boto.route53.record import ResourceRecordSets
import logging
import cgitb
import cgi
import os

logger = logging.getLogger(__name__)

console = logging.StreamHandler(sys.stdout)
formatter = logging.Formatter('[%(asctime)s] (%(levelname)s) %(message)s')
console.setFormatter(formatter)
logger.addHandler(console) 

handler = logging.FileHandler('/tmp/dyndns_route53.log')
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler) 

logger.setLevel(logging.DEBUG)

# Change this. Thanks.
HOSTED_ZONE = 'A0001000010001' # Your hosted_zone ID
DOMAIN_NAME = 'your.domain' # The domain to update
AWS_ACCESS_KEY = "AKIAAACHANGEMEPLEASE"
AWS_SECRET_KEY = "A71+this+also+needs+to+be+changed+thanks"

get_change_id = lambda response: response['ChangeInfo']['Id'].split('/')[-1]
get_change_status = lambda response: response['ChangeInfo']['Status']

def resolve_name_ip(name):
    resolver = dns.resolver.Resolver()
    resolver.nameservers = [
        '8.8.8.8',
        '8.8.4.4'
    ]
    answer = resolver.query(name)
    
    """
    >>> answer.response.answer[0].to_text()
    home.mydomain.com. 60 IN A 192.168.0.2'
    >>> answer.response.answer[0].items
    [<DNS IN A rdata: 192.168.0.2>]
    >>> answer.response.answer[0].items[0].address
    '192.168.0.2'
    """
    return answer.response.answer[0].items[0].address
    
def update_dns(current_ip):
    
    # Avoid to hit the Route53 API if is not necessary.
    # so compare first to a DNS server if the IP changed
    resolved_ip = resolve_name_ip(DOMAIN_NAME)
    if resolved_ip == current_ip:
        logger.debug('DNS response (%s) and public IP (%s) are the same, nothing to do' % (resolved_ip, current_ip))
        return
    
    conn = Route53Connection(aws_access_key_id = AWS_ACCESS_KEY, aws_secret_access_key = AWS_SECRET_KEY)

    try:
        zone = conn.get_hosted_zone(HOSTED_ZONE)
    except DNSServerError:
        logger.error('%s Zone Not Found' % HOSTED_ZONE)
        sys.exit(1)

    response = conn.get_all_rrsets(HOSTED_ZONE, 'A', DOMAIN_NAME, maxitems=1)[0]
    
    if current_ip not in response.resource_records:
        logger.info('Found new IP: %s' % current_ip)

        # Delete the old record, and create a new one.
        # This code is from route53.py script, the change record command
        changes = ResourceRecordSets(conn, HOSTED_ZONE, '')
        change1 = changes.add_change("DELETE", DOMAIN_NAME, 'A', response.ttl)
        for old_value in response.resource_records:
            change1.add_value(old_value)
        change2 = changes.add_change("CREATE", DOMAIN_NAME, 'A', response.ttl)
        change2.add_value(current_ip)

        try:
            commit = changes.commit()
            logger.debug('%s' % commit)
        except:
            logger.error("Changes can't be made: %s" % commit)
            sys.exit(1)
        else:
            
            change = conn.get_change(get_change_id(commit['ChangeResourceRecordSetsResponse']))
            logger.debug('%s' % change)

            while get_change_status(change['GetChangeResponse']) == 'PENDING':
                time.sleep(2)
                change = conn.get_change(get_change_id(change['GetChangeResponse']))
                logger.debug('%s' % change)                
            if get_change_status(change['GetChangeResponse']) == 'INSYNC':
                logger.info('Change %s A from %s to %s' % (DOMAIN_NAME, response.resource_records[0], current_ip))
            else:
                logger.warning('Unknown status for the change: %s' % change)
                logger.debug('%s' % change)

if __name__ == '__main__':
    cgitb.enable(0, "/tmp")

    print """Status: 200 OK
Content-Type: text/ascii
"""

    remote_ip = os.environ["REMOTE_ADDR"]

    update_dns(remote_ip)