When setting the IPv6 address for the metadata interface [2], it could happen that the IPv6 address can be considered as duplicated [2]. The IPv6 address in the DHCP namespace is set as "dadfailed tentative".
This is happening when using VLAN networks and HA DHCP agents and "enable_isolated_metadata=True". When the first DHCP agent boots, it configures the IPv6 address on the DHCP namespace interface (the metadata IPv6 address is METADATA_V6_IP='fe80::a9fe:a9fe'). Then the second DHCP agent tries to configure the same IPv6 address on the interface, but this IPv6 address is duplicated.
[2]https://github.com/openstack/neutron/blob/8455edda46b4a465e2f184b59ad31476ce79c6c4/neutron/agent/metadata/driver.py#L244-L246
[1]https://paste.opendev.org/show/bXDAHSHpvEAIHwdPjxrB/
Hi Bence:
Qq, when you implemented this feature, did you consider the HA case (maybe I'm doing something wrong)? Please ping me in IRC if you have some minutes.
Thanks!