This change causes kube-proxy to supply the required "-f ipv6"
family flag whenever the conntrack utility is executed and the
associated service is using IPv6.
This change is required for IPv6-only operation.
Note that unit test coverage for the 2-line changes in
pkg/proxy/iptables/proxier.go and /pkg/proxy/ipvs/proxier.go will need
to be added after support for IPv6 service addresses is added to these
files. For pkg/proxy/iptables/proxier.go, this coverage will be added
either with PR #48551.
fixes#52027
This changes the userspace proxy so that it cleans up its conntrack
settings when a service is removed (as the iptables proxy already
does). This could theoretically cause problems when a UDP service
as deleted and recreated quickly (with the same IP address). As
long as packets from the same UDP source IP and port were going to
the same destination IP and port, the the conntrack would apply and
the packets would be sent to the old destination.
This is astronomically unlikely if you did not specify the IP address
to use in the service, and even then, only happens with an "established"
UDP connection. However, in cases where a service could be "switched"
between using the iptables proxy and the userspace proxy, this case
becomes much more frequent.
