[MGM] Add --rm_fip_ignore_500 option

Add option to ignore HTTP 500 error when deleting the floating IP
from an instance and treat it as a successful response.

Change-Id: Ic81181795725823d4d953f2d9fae25775fb7c91d

doc/pool_mgm/config.rst

@@ -119,3 +119,7 @@ Command Line Options
       Used to specify the Gearman job server hostname and port. This option
       can be used multiple times to specify multiple job servers
 
+   .. option:: --rm_fip_ignore_500
+
+      When removing a floating IP, ignore the HTTP 500 error and treat it as
+      a successful response.

libra/mgm/mgm.py

@@ -155,6 +155,10 @@ def main():
         dest='threads', type=int, default=4,
         help='Number of worker threads to spawn'
     )
+    options.parser.add_argument(
+        '--rm_fip_ignore_500', action='store_true',
+        help='Ignore HTTP 500 error when removing a floating IP'
+    )
 
     args = options.run()
 

libra/mgm/nova.py

@@ -52,6 +52,8 @@ class Node(object):
         self.secgroup = args.nova_secgroup
         self.node_basename = args.node_basename
         self.az = args.nova_az_name
+        self.rm_fip_ignore_500 = args.rm_fip_ignore_500
+
         # Replace '_' with '-' in basename
         if self.node_basename:
             self.node_basename = self.node_basename.replace('_', '-')
@@ -99,17 +101,23 @@ class Node(object):
             )
 
     def vip_remove(self, node_id, vip):
-        """ assign a virtual IP to a Nova instance """
+        """ delete a virtual IP from a Nova instance """
         url = '/servers/{0}/action'.format(node_id)
         body = {
             "removeFloatingIp": {
                 "address": vip
             }
         }
-        resp, body = self.nova.post(url, body=body)
+        try:
+            resp, body = self.nova.post(url, body=body)
+        except exceptions.ClientException as e:
+            if e.code == 500 and self.rm_fip_ignore_500:
+                return
+            raise
+
         if resp.status_code != 202:
             raise Exception(
-                'Response code {0}, message {1} when assigning vip'
+                'Response code {0}, message {1} when removing vip'
                 .format(resp.status_code, body)
             )