Merge pull request #211 from edx/e0d/vpn-dns

initial working version

util/vpc-tools/vpc-dns.py

+"""vpc-dns.py
+
+Usage:
+    vpc-dns.py create-zone vpc <vpc-id>
+    vpc-dns.py (-h --help)
+    vpc-dns.py (-v --version)
+
+Options:
+    -h --help       Show this screen.
+    -v --version    Show version.
+"""
+import boto
+from boto.route53.record import ResourceRecordSets
+from docopt import docopt
+
+class VPCDns:
+    BACKEND_ZONE = "Z4AI6ADZTL3HN"
+    DNS_SUFFIX = ".vpc.edx.org"
+    ZONE = "{name}" + DNS_SUFFIX
+
+    def __init__(self,vpc_id=None):
+        self.vpc_id = vpc_id
+        self.elb = boto.connect_elb()
+        self.r53 = boto.connect_route53()
+
+    def create_zone(self, vpc_id):
+        zone_name = self.ZONE.format(name=vpc_id)
+        print zone_name
+        hosted_zone = self.get_or_create_hosted_zone(zone_name)
+
+        elbs = self.elb.get_all_load_balancers()
+
+        for elb in [x for x in elbs if x.vpc_id == self.vpc_id]:
+            self.create_service_dns(elb,self.get_zone_id_from_retval(
+                hosted_zone.Id),self.vpc_id)
+
+    def get_zone_id_from_retval(self,retval):
+        """
+        The data structure returned by the create_hosted_zone call
+        pre-pends the string /hostedzone/ to the Id for some reason.
+        """
+        return retval.replace("/hostedzone/","")
+
+
+    def get_or_create_hosted_zone(self, zone_name):
+
+        hosted_zone = self.r53.get_hosted_zone_by_name(zone_name)
+
+        if not hosted_zone:
+            zone_data = self.r53.create_hosted_zone(zone_name,
+                                        comment="Created by automation.")
+            hosted_zone = self.r53.get_hosted_zone_by_name(zone_name)
+
+        return hosted_zone
+
+
+    def get_elb_service(self, elb):
+
+        services = ["edxapp","rabbit","xqueue","xserver","worker"]
+
+        for service in services:
+            if service in elb.dns_name.lower():
+                return service
+
+        raise Exception("No service mapping for " + elb.dns_name)
+
+
+    def create_service_dns(self, elb, zone, vpc_id):
+        """
+        """
+        records = self.r53.get_all_rrsets(zone)
+
+        old_names = [r.name for r in records]
+
+        HOST_TEMPLATE = "{service}.{vpc_id}" + self.DNS_SUFFIX
+
+        service = self.get_elb_service(elb)
+
+        dns_name = HOST_TEMPLATE.format(service=service,
+                                        vpc_id=vpc_id)
+
+        change_set = ResourceRecordSets()
+
+        if dns_name + '.' in old_names:
+            print "adding delete"
+            change = change_set.add_change(
+                'DELETE',
+                dns_name,
+                'CNAME',
+                600)
+
+            change.add_value(elb.dns_name)
+
+        change = change_set.add_change(
+            'CREATE',
+            dns_name,
+            'CNAME',
+            600 )
+
+        change.add_value(elb.dns_name)
+
+        print change_set.to_xml()
+
+        self.r53.change_rrsets(zone, change_set.to_xml())
+
+VERSION="0.1"
+
+def dispatch(args):
+
+    vpc_id = args.get("<vpc-id>")
+
+    c = VPCDns(vpc_id=vpc_id)
+
+    if args.get("create-zone"):
+        c.create_zone(vpc_id)
+
+if __name__ == "__main__":
+    args = docopt(__doc__, version=VERSION)
+    dispatch(args)
+