Removed the host FQDN from the exception message

Deletion of an instance after disabling the hypervisor by a non-admin
 user leaks the host fqdn in fault msg of instance.Removing the
'host' field from the error message of HypervisorUnavaiable
cause it's leaking host fqdn to non-admin users. The admin user will
see the Hypervisor unavailable exception msg but will be able to figure
on which compute host the guest is on and that the connection is broken.

Change-Id: I0eae19399670f59c17c9a1a24e1bfcbf1b514e7b
Closes-Bug: #1851587
(cherry picked from commit a89ffab832)
(cherry picked from commit ff82601204)
(cherry picked from commit c5abbd17b5)
(cherry picked from commit d5ff9f87c8)
(cherry picked from commit 8c4af53d77)
(cherry picked from commit 4efdf632bc)

nova/exception.py

@@ -462,7 +462,7 @@ class ComputeResourcesUnavailable(ServiceUnavailable):
 
 
 class HypervisorUnavailable(NovaException):
-    msg_fmt = _("Connection to the hypervisor is broken on host: %(host)s")
+    msg_fmt = _("Connection to the hypervisor is broken on host")
 
 
 class ComputeServiceUnavailable(ServiceUnavailable):

nova/virt/libvirt/host.py

@@ -457,7 +457,7 @@ class Host(object):
             rpc.get_notifier('compute').error(nova_context.get_admin_context(),
                                               'compute.libvirt.error',
                                               payload)
-            raise exception.HypervisorUnavailable(host=CONF.host)
+            raise exception.HypervisorUnavailable()
 
         return conn
 

nova/virt/libvirt/volume/mount.py

@@ -84,7 +84,7 @@ class _HostMountStateManager(object):
         with self.cond:
             state = self.state
             if state is None:
-                raise exception.HypervisorUnavailable(host=CONF.host)
+                raise exception.HypervisorUnavailable()
             self.use_count += 1
 
         try: