Expose the reuse_fips flag on os_server (#4849)

* Expose the reuse_fips flag on os_server

* Remove useless line

cloud/openstack/os_server.py

@@ -185,6 +185,18 @@ options:
      required: false
      default: false
      version_added: "2.2"
+   reuse_fips:
+     description:
+       - When I(auto_ip) is true and this option is true, the I(auto_ip) code
+         will attempt to re-use unassigned floating ips in the project before
+         creating a new one. It is important to note that it is impossible
+         to safely do this concurrently, so if your use case involves
+         concurrent server creation, it is highly recommended to set this to
+         false and to delete the floating ip associated with a server when
+         the server is deleted using I(delete_fip).
+     required: false
+     default: true
+     version_added: "2.2"
 requirements:
     - "python >= 2.6"
     - "shade"
@@ -475,6 +487,7 @@ def _create_server(module, cloud):
         boot_volume=module.params['boot_volume'],
         boot_from_volume=module.params['boot_from_volume'],
         terminate_volume=module.params['terminate_volume'],
+        reuse_fips=module.params['reuse_fips'],
         wait=module.params['wait'], timeout=module.params['timeout'],
         **bootkwargs
     )
@@ -575,6 +588,7 @@ def main():
         scheduler_hints                 = dict(default=None, type='dict'),
         state                           = dict(default='present', choices=['absent', 'present']),
         delete_fip                      = dict(default=False, type='bool'),
+        reuse_fips                      = dict(default=True, type='bool'),
     )
     module_kwargs = openstack_module_kwargs(
         mutually_exclusive=[