git.squeep.com Git - awsible/blob - roles/vpcaccess/files/routeUpdater.py

   1 #!/usr/bin/python
   2
   3 import boto.utils
   4 import boto.ec2
   5 import boto.vpc
   6 import sys
   7
   8 dry_run = False
   9
  10 # AWS access/secret keys
  11 aws_access      = None
  12 aws_secret      = None
  13
  14 # Get all of the instance info e.g. curl 169.254.169.254/latest/meta-data/
  15 try:
  16     instance_info = boto.utils.get_instance_metadata()
  17 except:
  18     print "Could not get EC2 instance ID!"
  19     sys.exit(1)
  20
  21 instance_id = instance_info['instance-id']
  22 region_name = instance_info['placement']['availability-zone'][:-1]
  23 vpc_id      = instance_info['network']['interfaces']['macs'][instance_info['mac']]['vpc-id']
  24
  25 vpc_conn = boto.vpc.connect_to_region(region_name, aws_access_key_id=aws_access, aws_secret_access_key=aws_secret)
  26 ec2_conn = boto.ec2.connect_to_region(region_name, aws_access_key_id=aws_access, aws_secret_access_key=aws_secret)
  27
  28 # Turn off Source/Destination checking if it's on
  29 source_dest_check = ec2_conn.get_instance_attribute(instance_id, 'sourceDestCheck')['sourceDestCheck']
  30 print "Source/Dest check: %s" % (source_dest_check,)
  31
  32 if source_dest_check:
  33     print "Instance must have source/dest checking disabled to NAT properly!"
  34     try:
  35         ec2_conn.modify_instance_attribute(instance_id, 'sourceDestCheck', False, dry_run=dry_run)
  36     except Exception, e:
  37         print "Could not modify source/dest check: %s" % (e,)
  38         sys.exit(1)
  39
  40 # Get the managed route tables for my VPC
  41 rt = vpc_conn.get_all_route_tables(filters={'vpc_id':vpc_id,'tag:managed':'yes'})
  42
  43 # Just in case there's more than one
  44 for table in rt:
  45     # See if there's a default route (0.0.0.0/0)
  46     gw_route = next((route for route in table.routes if route.destination_cidr_block == '0.0.0.0/0'), None)
  47     if not gw_route:
  48         print "Could not find default gw route in routing table!"
  49     else:
  50         print "Found a gateway route: %s, %s, %s" % (table.id, gw_route.destination_cidr_block, instance_id)
  51         try:
  52             # If there is delete it, because I'm taking it over
  53             vpc_conn.delete_route(table.id, '0.0.0.0/0', dry_run=dry_run)
  54         except Exception, e:
  55             print "Could not delete gw route! %s" % (e,)
  56             sys.exit(1)
  57     try:
  58         # Make me the default route, I'm the router now!
  59         vpc_conn.create_route(table.id, '0.0.0.0/0', instance_id=instance_id, dry_run=dry_run)
  60     except Exception, e:
  61         print "Could not replace gw route! %s" % (e,)
  62         sys.exit(1)
  63
  64