now the enable_isolated_metadata_proxy is always called no matter what is the enable_isolated_metadata option value.
In fact, if enable_isolated_metadata=False, the proxy should not work according to code:
1. def _output_opts_file(self) in dhcp.py:
"""Write a dnsmasq compatible options file."""
...
host_routes = ["%s,%s" % (hr.destination, hr.nexthop)
for hr in subnet.host_routes]
subnet_dhcp_ip = subnet_to_interface_ip[subnet.id]
# Add host routes for isolated network segments
enable_metadata = (
self.conf.enable_isolated_metadata
and not subnet.gateway_ip
and subnet.ip_version == 4)
if enable_metadata:
host_routes.append(
'%s/32,%s' % (METADATA_DEFAULT_IP, subnet_dhcp_ip)
)
So if enable_isolated_metadata, dnsmasq will use host router to lead 169.254.169.254 traffic of VM to IP of dnsmasq is listensing.
2. def setup(self, network, reuse_existing=False): in dhcp_agent.py
"""Create and initialize a device for network's DHCP on this host."""
device_id = self.get_device_id(network)
port = self.plugin.get_dhcp_port(network.id, device_id)
interface_name = self.get_interface_name(network, port)
if self.conf.use_namespaces:
namespace = NS_PREFIX + network.id
else:
namespace = None
if ip_lib.device_exists(interface_name,
self.root_helper,
namespace):
if not reuse_existing:
raise exceptions.PreexistingDeviceFailure(
dev_name=interface_name)
LOG.debug(_('Reusing existing device: %s.'), interface_name)
else:
self.driver.plug(network.id,
port.id,
interface_name,
port.mac_address,
namespace=namespace)
ip_cidrs = []
for fixed_ip in port.fixed_ips:
subnet = fixed_ip.subnet
net = netaddr.IPNetwork(subnet.cidr)
ip_cidr = '%s/%s' % (fixed_ip.ip_address, net.prefixlen)
ip_cidrs.append(ip_cidr)
if (self.conf.enable_isolated_metadata and
self.conf.use_namespaces):
ip_cidrs.append(METADATA_DEFAULT_IP)
so we are adding '169.254.169.254/%d' % METADATA_DEFAULT_PREFIX (16) to dhcp tap device.
the metadata_proxy process should not be called if self.conf.enable_isolated_metadata is false.
more information:
gongysh@
18: lo: <LOOPBACK,
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
23: tap129fb738-09: <BROADCAST,
link/ether fa:16:3e:f3:38:60 brd ff:ff:ff:ff:ff:ff
inet 10.0.1.4/24 brd 10.0.1.255 scope global tap129fb738-09
inet 169.254.169.254/16 brd 169.254.255.255 scope global tap129fb738-09
inet6 fe80::f816:
valid_lft forever preferred_lft forever