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EIP Failover II #2

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EIP Failover II #2

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56 changes: 31 additions & 25 deletions nat-handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,11 +56,12 @@
import json
import os
import sys
import time

from boto.ec2 import connect_to_region as connect_to_ec2
from boto.vpc import connect_to_region as connect_to_vpc
from boto.utils import get_instance_metadata
from subprocess import call
from subprocess import call, check_output


NAT_CONFIG = '/etc/nat.conf'
Expand Down Expand Up @@ -91,12 +92,6 @@ def eth1_id(self, az):
return entry.get('eth1_id')
return None

def eth2_id(self, az):
entry = self.config_dict[az]
if isinstance(entry, dict):
return entry.get('eth2_id')
return None


class Rerouter(object):
def __init__(self, config):
Expand All @@ -119,41 +114,50 @@ def current_region(self):
def eth0_id(self):
ec2 = connect_to_ec2(self.current_region)
instance = ec2.get_only_instances(instance_ids=[self.current_instance_id])[0]
eth0 = [i for i in instance.interfaces if i.id not in [self.eth1_id, self.eth2_id]]
eth0 = [i for i in instance.interfaces if i.id != self.eth1_id]
return eth0[0].id

@property
def eth1_id(self):
return self.config.eth1_id(self.current_az)

@property
def eth2_id(self):
return self.config.eth2_id(self.current_az)

def supports_elastic_ip(self, az):
return self.config.elastic_ip_allocation_id(az) != None

def take_route(self, az):
''' If the az supports elatcic ip, reroute on eth1 because eth1 is associated with elastic ip
otherwise reroute on eth0 which is also public. In both cases outward traffic to the internet will be possible.
'''
route_table_id = self.config.route_table_id(az)
interface_id = self.eth1_id if self.supports_elastic_ip(az) else self.eth0_id
vpc = connect_to_vpc(self.current_region)
vpc.replace_route(route_table_id, '0.0.0.0/0', interface_id=interface_id)
vpc.replace_route(route_table_id, '0.0.0.0/0', interface_id=self.eth0_id)

def take_elastic_ip(self, az):
''' EIP fails over onto interface id if provided or instance id '''
elastic_ip_allocation_id = self.config.elastic_ip_allocation_id(az)
if elastic_ip_allocation_id:
ec2 = connect_to_ec2(self.current_region)
interface_id = self.eth1_id if az == self.current_az else self.eth2_id
if interface_id:
ec2.associate_address(network_interface_id=interface_id,
allocation_id=elastic_ip_allocation_id, allow_reassociation=True)
else:
ec2.associate_address(self.current_instance_id,
allocation_id=elastic_ip_allocation_id, allow_reassociation=True)
interface_id = self.eth0_id if az == self.current_az else self.eth1_id
ec2.associate_address(network_interface_id=interface_id,
allocation_id=elastic_ip_allocation_id, allow_reassociation=True)

def detach_interface(self):
ec2 = connect_to_ec2(self.current_region)
interface = ec2.get_all_network_interfaces(filters={'network_interface_id': self.eth1_id})
if interface and interface[0].status == 'in-use':
interface[0].detach(True)

def attach_interface(self):
device_index = 1
ec2 = connect_to_ec2(self.current_region)
interface = ec2.get_all_network_interfaces(filters={'network_interface_id': self.eth1_id})
if interface and interface[0].status == 'available':
ec2.attach_network_interface(self.eth1_id, self.current_instance_id, device_index)
while True:
call("ifdown --force eth1 2> /dev/null && ifup --force eth1", shell=True)
dev = check_output('ifconfig | grep -o eth1 || echo ""', shell=True).strip()
if dev == "eth1":
print 'eth1 is up'
break
else:
print 'eth1 is not up. Retrying ...'
time.sleep(1)

def __call__(self, az=None):
az = az or self.current_az
Expand Down Expand Up @@ -220,10 +224,12 @@ def main():
if quorum():
if event == 'member-join':
reroute()
reroute.detach_interface()
elif event in ['member-leave', 'member-failed']:
members = map(SerfMember.parse, sys.stdin.readlines())
nats = [x for x in members if x.role == 'nat']
for nat in nats:
reroute.attach_interface()
reroute(nat.az)


Expand Down