systemd 242+ assigns MAC addresses for all virtual devices which don't
have the address assigned already. That resulted in systemd overriding
MAC addresses of flannel.* interfaces. The fix which prevents systemd
from setting the address is to define the concrete MAC address when
creating the link.

Fixes: flannel-io#1155
Ref: k3s-io/k3s#4188
Signed-off-by: Michal Rostecki <[email protected]>
(cherry picked from commit 0198d5d)

Currently flannel interface ip addresses are checked on startup when
using vxlan and ipip backends. If multiple addresses are found, startup
fails fatally. If only one address is found and is not the currently
leased one, it will be assumed that it comes from a previous lease and
be removed.

This criteria seems arbitrary both in how it is done and in its timing.
It may cause failures in situations where it might not be strictly
necessary like for example if the node is running a dhcp client that is
assigning link local addresses to all interfaces. It also might fail at
flannel unexpected restarts which are completly unrelated to
the external event that caused the unexpected modification in the
flannel interface.

This patch proposes to concern and check only ip address within the
flannel network and takes the simple approach to ignore any other ip
addresses assuming these would pose no problem on flannel operation.

A discarded but more agressive alternative would be to remove all
addresses that are not the currently leased one.

Fixes flannel-io#1060

Signed-off-by: Jaime Caamaño Ruiz <[email protected]>
(cherry picked from commit 33a2fac)

(cherry picked from commit 78035d0)

This PR fixs an issue when flannel gets illegal subnet event in
watching leases, it doesn't move forward the etcd cursor and
will stuck in the same invalid event forever.

(cherry picked from commit 1a1b6f1)

…d in our fork