Since [1], we restart the HAProxy process of each network (datapath) in order to "honor any potential changes in their configuration." [2].

This process could slow down the OVN Metadata agent restart and could potentially interfere with a VM boot-up if the HAProxy process is restarted in the middle.

This bug proposes an optimization that checks the IPv6 support of the HAProxy running process to decide to restart it or not.

[1]https://code.engineering.redhat.com/gerrit/c/neutron/+/453217

[2]https://code.engineering.redhat.com/gerrit/c/neutron/+/453217/2/neutron/agent/ovn/metadata/agent.py#359

U/S launchpad: https://bugs.launchpad.net/neutron/+bug/2079996