Linux startup script to update Route53 zone entry using the EC2 dynamically allocated IP address.

update53-couchdb.py

#!/usr/bin/python

### BEGIN INIT INFO
# Provides:             update53
# Required-Start:       $network $local_fs
# Required-Stop:
# Should-Start:
# Should-Stop:
# X-Start-Before:       couchbase-server
# X-Stop-After:         couchbase-server
# Default-Start:        2 3 4 5
# Default-Stop:         0 1 6
# Short-Description:    Update Route53
# Description:          Update Route53 zone to reflect IP address.
### END INIT INFO

import boto
import boto.ec2
import boto.route53.record
import requests

region = 'ap-northeast-1'
access_key = 'XXXXXXXXXXXXXXXXXXXX'
secret_access_key = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
route53_zone_id = 'XXXXXXXXXXXXXX'
domain = 'example.com.' # last '.' required.
subdomain_public = 'ec2'
subdomain_local = 'ec2local'

def getname(instanceid):
  conn = boto.ec2.connect_to_region(region, aws_access_key_id=access_key, aws_secret_access_key=secret_access_key)
  return conn.get_all_instances(instanceid)[0].instances[0].tags['Name']

def getinstanceid():
  return requests.get('http://169.254.169.254/latest/meta-data/instance-id').content

def getlocalip():
  return requests.get('http://169.254.169.254/latest/meta-data/local-ipv4').content

def getpublicip():
  return requests.get('http://169.254.169.254/latest/meta-data/public-ipv4').content

def route53_delete(name):
  name = name + '.' + domain
  print 'Route53 Delete %s' % name
  conn = boto.connect_route53(access_key, secret_access_key)
  changes = boto.route53.record.ResourceRecordSets(conn, route53_zone_id)
  for rr in conn.get_all_rrsets(route53_zone_id, 'A', name, maxitems=10):
    if rr.name != name or rr.type != 'A':
      continue
    change = changes.add_change('DELETE', name, 'A')
    for ip in rr.resource_records:
      change.add_value(ip)
  changes.commit()

def route53_update(name, ipaddr):
  name = name + '.' + domain
  print 'Route53 Update %s %s' % (name, ipaddr)
  conn = boto.connect_route53(access_key, secret_access_key)
  changes = boto.route53.record.ResourceRecordSets(conn, route53_zone_id)
  for rr in conn.get_all_rrsets(route53_zone_id, 'A', name, maxitems=10):
    if rr.name != name or rr.type != 'A':
      continue
    change = changes.add_change('DELETE', name, 'A')
    for ip in rr.resource_records:
      change.add_value(ip)
  change = changes.add_change('CREATE', name, 'A')
  for ip in ipaddr.split(','):
    change.add_value(ip)
  changes.commit()
  return name[:-1]      # remove last '.'

def sethostname(fname, hostname):
  with open(fname, 'w') as fp:
    fp.write(hostname)

def create_hosts(entries):
  template = '''127.0.0.1 localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

# Added by /etc/init.d/update53
'''
  with open('/etc/hosts', 'w') as fp:
    fp.write(template)
    for name, ipaddr in entries:
      fp.write('%s %s\n' % (ipaddr, name))

def main():
  import sys
  import os

  if len(sys.argv) == 1:
    name = getname(getinstanceid())
    publicip = getpublicip()
    localip = getlocalip()
    print 'EC2 instance name=%s public=%s local=%s' % (name, publicip, localip)
  elif len(sys.argv) == 2:
    name = getname(getinstanceid())
    publicip = getpublicip()
    localip = getlocalip()
    if sys.argv[1] == 'start':
      publichost = route53_update(name + '.' + subdomain_public, publicip)
      localhost = route53_update(name + '.' + subdomain_local, localip)

      sethostname('/etc/hostname', name)
      sethostname('/opt/couchbase/var/lib/couchbase/ip_start', localhost)
      os.system('hostname "%s"' % name)
      create_hosts([
        (localhost + ' ' + name, localip),
      ])
    elif sys.argv[1] == 'stop':
      route53_delete(name + '.' + subdomain_public)
      route53_delete(name + '.' + subdomain_local)
  else:
    print 'Usage: %s {start|stop}' % sys.argv[0].split('/')[-1]
    sys.exit(1)

if __name__ == '__main__':
  main()

update53.py

#!/usr/bin/python

### BEGIN INIT INFO
# Provides:             update53
# Required-Start:       $network $local_fs
# Required-Stop:
# Should-Start:
# Should-Stop:
# X-Start-Before:
# X-Stop-After:
# Default-Start:        2 3 4 5
# Default-Stop:         0 1 6
# Short-Description:    Update Route53
# Description:          Update Route53 zone to reflect IP address.
### END INIT INFO

import boto
import boto.ec2
import boto.route53.record
import requests

region = 'ap-northeast-1'
access_key = 'XXXXXXXXXXXXXXXXXXXX'
secret_access_key = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
route53_zone_id = 'XXXXXXXXXXXXXX'
domain = 'example.com.' # last '.' required.
subdomain_public = 'ec2'
subdomain_local = 'ec2local'

def getname(instanceid):
  conn = boto.ec2.connect_to_region(region, aws_access_key_id=access_key, aws_secret_access_key=secret_access_key)
  return conn.get_all_instances(instanceid)[0].instances[0].tags['Name']

def getinstanceid():
  return requests.get('http://169.254.169.254/latest/meta-data/instance-id').content

def getlocalip():
  return requests.get('http://169.254.169.254/latest/meta-data/local-ipv4').content

def getpublicip():
  return requests.get('http://169.254.169.254/latest/meta-data/public-ipv4').content

def route53_delete(name):
  name = name + '.' + domain
  print 'Route53 Delete %s' % name
  conn = boto.connect_route53(access_key, secret_access_key)
  changes = boto.route53.record.ResourceRecordSets(conn, route53_zone_id)
  for rr in conn.get_all_rrsets(route53_zone_id, 'A', name, maxitems=10):
    if rr.name != name or rr.type != 'A':
      continue
    change = changes.add_change('DELETE', name, 'A')
    for ip in rr.resource_records:
      change.add_value(ip)
  changes.commit()

def route53_update(name, ipaddr):
  name = name + '.' + domain
  print 'Route53 Update %s %s' % (name, ipaddr)
  conn = boto.connect_route53(access_key, secret_access_key)
  changes = boto.route53.record.ResourceRecordSets(conn, route53_zone_id)
  for rr in conn.get_all_rrsets(route53_zone_id, 'A', name, maxitems=10):
    if rr.name != name or rr.type != 'A':
      continue
    change = changes.add_change('DELETE', name, 'A')
    for ip in rr.resource_records:
      change.add_value(ip)
  change = changes.add_change('CREATE', name, 'A')
  for ip in ipaddr.split(','):
    change.add_value(ip)
  changes.commit()

def main():
  import sys
  if len(sys.argv) == 1:
    name = getname(getinstanceid())
    publicip = getpublicip()
    localip = getlocalip()
    print 'EC2 instance name=%s public=%s local=%s' % (name, publicip, localip)
  elif len(sys.argv) == 2:
    name = getname(getinstanceid())
    publicip = getpublicip()
    localip = getlocalip()
    if sys.argv[1] == 'start':
      route53_update(name + '.' + subdomain_public, publicip)
      route53_update(name + '.' + subdomain_local, localip)
    elif sys.argv[1] == 'stop':
      route53_delete(name + '.' + subdomain_public)
      route53_delete(name + '.' + subdomain_local)
  else:
    print 'Usage: %s {start|stop}' % sys.argv[0].split('/')[-1]
    sys.exit(1)

if __name__ == '__main__':
  main()