this adds back the ability to configure
the rabbitmq/erlang kernel network interface
which was removed in https://review.opendev.org/#/c/584427/
seemingly by accident.

Closes-Bug: 1900160

Change-Id: I6f00396495853e117429c17fadfafe809e322a31

Introduce kolla_address filter.
Introduce put_address_in_context filter.

Add AF config to vars.

Address contexts:
- raw (default): <ADDR>
- memcache: inet6:[<ADDR>]
- url: [<ADDR>]

Other changes:

globals.yml - mention just IP in comment

prechecks/port_checks (api_intf) - kolla_address handles validation

3x interface conditional (swift configs: replication/storage)

2x interface variable definition with hostname
(haproxy listens; api intf)

1x interface variable definition with hostname with bifrost exclusion
(baremetal pre-install /etc/hosts; api intf)

neutron's ml2 'overlay_ip_version' set to 6 for IPv6 on tunnel network

basic multinode source CI job for IPv6

prechecks for rabbitmq and qdrouterd use proper NSS database now

MariaDB Galera Cluster WSREP SST mariabackup workaround
(socat and IPv6)

Ceph naming workaround in CI
TODO: probably needs documenting

RabbitMQ IPv6-only proto_dist

Ceph ms switch to IPv6 mode

Remove neutron-server ml2_type_vxlan/vxlan_group setting
as it is not used (let's avoid any confusion)
and could break setups without proper multicast routing
if it started working (also IPv4-only)

haproxy upgrade checks for slaves based on ipv6 addresses

TODO:

ovs-dpdk grabs ipv4 network address (w/ prefix len / submask)
not supported, invalid by default because neutron_external has no address
No idea whether ovs-dpdk works at all atm.

ml2 for xenapi
Xen is not supported too well.
This would require working with XenAPI facts.

rp_filter setting
This would require meddling with ip6tables (there is no sysctl param).
By default nothing is dropped.
Unlikely we really need it.

ironic dnsmasq is configured IPv4-only
dnsmasq needs DHCPv6 options and testing in vivo.

KNOWN ISSUES (beyond us):

One cannot use IPv6 address to reference the image for docker like we
currently do, see: https://github.com/moby/moby/issues/39033
(docker_registry; docker API 400 - invalid reference format)
workaround: use hostname/FQDN

RabbitMQ may fail to bind to IPv6 if hostname resolves also to IPv4.
This is due to old RabbitMQ versions available in images.
IPv4 is preferred by default and may fail in the IPv6-only scenario.
This should be no problem in real life as IPv6-only is indeed IPv6-only.
Also, when new RabbitMQ (3.7.16/3.8+) makes it into images, this will
no longer be relevant as we supply all the necessary config.
See: https://github.com/rabbitmq/rabbitmq-server/pull/1982

For reliable runs, at least Ansible 2.8 is required (2.8.5 confirmed
to work well). Older Ansible versions are known to miss IPv6 addresses
in interface facts. This may affect redeploys, reconfigures and
upgrades which run after VIP address is assigned.
See: https://github.com/ansible/ansible/issues/63227

Bifrost Train does not support IPv6 deployments.
See: https://storyboard.openstack.org/#!/story/2006689



Change-Id: Ia34e6916ea4f99e9522cd2ddde03a0a4776f7e2c
Implements: blueprint ipv6-control-plane
Signed-off-by: Radosław Piliszek <radoslaw.piliszek@gmail.com>