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Separate nat and eip failover functionality #4

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46 changes: 31 additions & 15 deletions nat-handler.py → nat-and-eip-handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@
from subprocess import call, check_output


NAT_CONFIG = '/etc/nat.conf'
ROLE = '-'.join(os.environ['CLUSTER'].split('-')[1:])
logger = None


Expand Down Expand Up @@ -128,11 +128,15 @@ def supports_elastic_ip(self, az):
return self.config.elastic_ip_allocation_id(az) != None

def take_route(self, az):
if ROLE != 'nat':
return
route_table_id = self.config.route_table_id(az)
vpc = connect_to_vpc(self.current_region)
vpc.replace_route(route_table_id, '0.0.0.0/0', interface_id=self.eth0_id)

def take_elastic_ip(self, az):
if ROLE != 'eip':
return
elastic_ip_allocation_id = self.config.elastic_ip_allocation_id(az)
if elastic_ip_allocation_id:
ec2 = connect_to_ec2(self.current_region)
Expand All @@ -141,12 +145,16 @@ def take_elastic_ip(self, az):
allocation_id=elastic_ip_allocation_id, allow_reassociation=True)

def detach_interface(self):
if ROLE != 'eip':
return
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):
if ROLE != 'eip':
return
device_index = 1
ec2 = connect_to_ec2(self.current_region)
interface = ec2.get_all_network_interfaces(filters={'network_interface_id': self.eth1_id})
Expand Down Expand Up @@ -183,7 +191,7 @@ def quorum(self):

def alive(self, n):
''' Returns True if at least n nats are alive. '''
cmd = "serf members -tag role=nat -status=alive -format json | jq '.members | length >= %s' | grep true" % n
cmd = "serf members -tag role=%s -status=alive -format json | jq '.members | length >= %s' | grep true" % (ROLE, n)
res = call(cmd, shell=True)
return res == 0

Expand Down Expand Up @@ -222,31 +230,39 @@ def log(message, level=logging.INFO):
global logger
if not logger:
logger = logging.getLogger('serf-handler')
logger.addHandler(logging.handlers.SysLogHandler(address='/dev/log'))
logger.addHandler(logging.handlers.SysLogHandler(address='/dev/log'))
logger.setLevel(logging.DEBUG)

event = os.environ['SERF_EVENT']
logger.log(level, '[NAT-FAILOVER] event=%s, message=%s' % (event, message))
logger.log(level, '[%s-FAILOVER] event=%s, message=%s' % (ROLE, event, message))


def get_nats_from_serf_event():
def get_serf_members():
members = map(SerfMember.parse, sys.stdin.readlines())
nats = [x for x in members if x.role == 'nat']
return nats
members = [x for x in members if x.role == ROLE]
return members


def main():
with open(NAT_CONFIG) as f:
if ROLE == 'nat':
config_location = '/etc/nat.conf'
elif ROLE == 'eip':
config_location = '/etc/eip.conf'
else:
log("Invalid role " % ROLE)
raise("Invalid role to run nat-and-eip-handler.py script")

with open(config_location) as f:
config = Config(json.load(f))
event = os.environ['SERF_EVENT']
log("Serf-handler called")

try:
quorum = Quorum(config)
reroute = Rerouter(config)
nats = get_nats_from_serf_event()
if not nats:
log('No nat involved. Ignoring.')
members = get_serf_members()
if not members:
log('No members involved. Ignoring.')
return

if not quorum():
Expand All @@ -259,11 +275,11 @@ def main():
reroute.detach_interface()
log('Detach interface done')
elif event in ['member-leave', 'member-failed']:
for nat in nats:
for member in members:
reroute.attach_interface()
log('Attach interface for az=%s done' % nat.az)
reroute(az=nat.az)
log('Re-route done for az=%s done' % nat.az)
log('Attach interface for az=%s done' % member.az)
reroute(az=member.az)
log('Re-route done for az=%s done' % member.az)
except Exception as ex:
log('Exception in failover logic: %s' % ex, level=logging.ERROR)

Expand Down