Use Neutron (if available) to create floating IPs for validation

The 2.36 microversion in the compute API deprecates the os-floating-ips
API since it's a proxy when using Neutron, and nova-network is deprecated.

When ssh validation is enabled in a Tempest run, we should create the
floating IP using Neutron if available and only fallback to the compute
API if using nova-network.

Change-Id: Ib345abdeec17fef85f99beb0ff4f3639e95acf6f
diff --git a/tempest/common/validation_resources.py b/tempest/common/validation_resources.py
index b15796f..9e83a07 100644
--- a/tempest/common/validation_resources.py
+++ b/tempest/common/validation_resources.py
@@ -80,10 +80,23 @@
             validation_data['security_group'] = \
                 create_ssh_security_group(os, add_rule)
         if validation_resources['floating_ip']:
-            floating_client = os.compute_floating_ips_client
-            validation_data.update(
-                floating_client.create_floating_ip(
-                    pool=CONF.network.floating_network_name))
+            if CONF.service_available.neutron:
+                floatingip = os.floating_ips_client.create_floatingip(
+                    floating_network_id=CONF.network.public_network_id)
+                # validation_resources['floating_ip'] has historically looked
+                # like a compute API POST /os-floating-ips response, so we need
+                # to mangle it a bit for a Neutron response with different
+                # fields.
+                validation_data['floating_ip'] = floatingip['floatingip']
+                validation_data['floating_ip']['ip'] = (
+                    floatingip['floatingip']['floating_ip_address'])
+            else:
+                # NOTE(mriedem): The os-floating-ips compute API was deprecated
+                # in the 2.36 microversion. Any tests for CRUD operations on
+                # floating IPs using the compute API should be capped at 2.35.
+                validation_data.update(
+                    os.compute_floating_ips_client.create_floating_ip(
+                        pool=CONF.network.floating_network_name))
     return validation_data