AddFloatingIP refers to an old nova proxy API to neutron that was
deprecated in nova. The neutron API for floating IP associate requires
a port to be specified. Currently, the code is selecting the first port
if the server has multiple ports. But, an attempt to associate the
first port with a floating IP can fail if the first port is not on a
network that is attached to an external gateway.
In order to make the command work better for users who have a server
with multiple ports, we can:
1. Select the port corresponding to the fixed_ip_address, if one was
specified
2. Try to associate the floating IP with each port until one of the
attempts succeeds, else re-raise the last exception.
(404 ExternalGatewayForFloatingIPNotFound from neutron)
This also fixes incorrect FakeFloatingIP attributes that were being set
in the TestServerAddFloatingIPNetwork unit tests, which were causing
the tests to use None as parsed args for ip-address and
--fixed-ip-address and thus bypassing code in the
'if parsed_args.fixed_ip_address:' block.
Task: 27800
Story: 2004263
Change-Id: I11fbcebf6b00f12a030b000c84dcf1d6b5e86250
(cherry picked from commit 013c9a4f3a44cb0b81fc7affe9b933e701cb5dba)