Check missed ip6tables utility
In some scenario, like in OpenStack Kolla, system may lack
iptables-ipv6 package. This may cause command ip6tables-save
or ip6tables-restore invalid and ovs-agent error.
This patch allows checking ip6tables support from CLI:
neutron-sanity-check --ip6tables_installed
Or using configuration options, for example:
neutron-sanity-check --config-file /etc/neutron/neutron.conf
--config-file /etc/neutron/plugins/ml2/ml2_conf.ini
Change-Id: Ia6cf1ed6b5033442f03eac61d2d0d783c146d797
Closes-Bug: #
1530042