An interface with an external DNS service is defined for Neutron. A reference
implementation is also included, based on Designate. The interface and the
driver will enable users to publish in the external DNS service the dns_name
and dns_domain attributes associated with floating ips, ports and networks. As
a consequence, the floating ips and networks api is extended to manage dns_name
and dns_domain attributes. The dns_name attribute was added to ports in a
preceding commit
DocImpact: Introduce config option external_dns_driver to specify a driver
for external dns integration. For more info, see
doc/source/devref/external_dns_integration.rst
APIImpact
Implements: blueprint external-dns-resolution
Change-Id: Ic298ad2558410ab9a614f22e1757d1fc8b22c482
93ac8b3a33