Add new /2/features RAPI resource

The /2/features RAPI resource can be used to detect optional
features implemented by the RAPI server. This will be used
to recognize servers implementing a new request format for
instance creation requests.
Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

doc/rapi.rst

@@ -280,6 +280,19 @@ It supports the following commands: ``PUT``.
 Redistribute configuration to all nodes. The result will be a job id.
 
 
+``/2/features``
++++++++++++++++
+
+``GET``
+~~~~~~~
+
+Returns a list of features supported by the RAPI server. Available
+features:
+
+``instance-create-reqv1``
+  Instance creation request data version 1 supported.
+
+
 ``/2/instances``
 ++++++++++++++++
 

lib/rapi/client.py

@@ -39,6 +39,7 @@ HTTP_GET = "GET"
 HTTP_PUT = "PUT"
 HTTP_POST = "POST"
 HTTP_OK = 200
+HTTP_NOT_FOUND = 404
 HTTP_APP_JSON = "application/json"
 
 REPLACE_DISK_PRI = "replace_on_primary"
@@ -433,6 +434,23 @@ class GanetiRapiClient(object):
     """
     return self._SendRequest(HTTP_GET, "/version", None, None)
 
+  def GetFeatures(self):
+    """Gets the list of optional features supported by RAPI server.
+
+    @rtype: list
+    @return: List of optional features
+
+    """
+    try:
+      return self._SendRequest(HTTP_GET, "/%s/features" % GANETI_RAPI_VERSION,
+                               None, None)
+    except GanetiApiError, err:
+      # Older RAPI servers don't support this resource
+      if err.code == HTTP_NOT_FOUND:
+        return []
+
+      raise
+
   def GetOperatingSystems(self):
     """Gets the Operating Systems running in the Ganeti cluster.
 

lib/rapi/connector.py

@@ -216,6 +216,7 @@ def GetHandlers(node_name_pattern, instance_name_pattern, job_id_pattern):
     "/2/info": rlib2.R_2_info,
     "/2/os": rlib2.R_2_os,
     "/2/redistribute-config": rlib2.R_2_redist_config,
+    "/2/features": rlib2.R_2_features,
     }
 
 

lib/rapi/rlib2.py

@@ -118,6 +118,18 @@ class R_2_info(baserlib.R_Generic):
     return client.QueryClusterInfo()
 
 
+class R_2_features(baserlib.R_Generic):
+  """/2/features resource.
+
+  """
+  @staticmethod
+  def GET():
+    """Returns list of optional RAPI features implemented.
+
+    """
+    return []
+
+
 class R_2_os(baserlib.R_Generic):
   """/2/os resource.
 

test/ganeti.rapi.client_unittest.py

@@ -190,6 +190,12 @@ class GanetiRapiClientTests(testutils.GanetiTestCase):
     self.assertEqual(2, self.client.GetVersion())
     self.assertHandler(rlib2.R_version)
 
+  def testGetFeatures(self):
+    for features in [[], ["foo", "bar", "baz"]]:
+      self.rapi.AddResponse(serializer.DumpJson(features))
+      self.assertEqual(features, self.client.GetFeatures())
+      self.assertHandler(rlib2.R_2_features)
+
   def testGetOperatingSystems(self):
     self.rapi.AddResponse("[\"beos\"]")
     self.assertEqual(["beos"], self.client.GetOperatingSystems())