title: Python not able to connect to grpc channel -> "failed to connect to all addresses" "grpc_status":14
body: <p>I'm getting the error below when trying to call a stub method. 
  Any idea what is causing it? </p>
  
  <pre><code>[bolt.api.handlers] 2019-08-21 20:07:57,792 ERROR handlers:1066: 'ResourceHandler' object has no attribute 'ontology_service_handler'
  Traceback (most recent call last):
    File "/bolt-webserver/bolt/api/onse/onse_handlers/ontology_service.py", line 17, in post
      ontology_id = await self.onse_stub.createOntology()
    File "/bolt-webserver/bolt/api/onse/onse_stub.py", line 41, in createOntology
      return self.stub.CreateOntology(ontology_messages_pb2.Ontology())
    File "/usr/local/lib/python3.6/site-packages/grpc/_channel.py", line 565, in __call__
      return _end_unary_response_blocking(state, call, False, None)
    File "/usr/local/lib/python3.6/site-packages/grpc/_channel.py", line 467, in _end_unary_response_blocking
      raise _Rendezvous(state, None, None, deadline)
  grpc._channel._Rendezvous: &lt;_Rendezvous of RPC that terminated with:
          status = StatusCode.UNAVAILABLE
          details = "failed to connect to all addresses"
          debug_error_string = "{"created":"@1566418077.791002345","description":"Failed to pick subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":3818,"referenced_errors":[{"created":"@1566418077.790965749","description":"failed to connect to all addresses","file":"src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc","file_line":395,"grpc_status":14}]}"
  </code></pre>
  
  <p>I've tried to provide ip address instead of hostname but still getting the same error . The OnseStub class is initialized right before calling  createOntology method.
  The service is up and running.
  The failing call is done from a tornado web app (in case that might matter) </p>
  
  <pre><code>class OnseStub:
  
      def __init__(self, ontology_service_backend):
      self.channel = grpc.insecure_channel('localhost:51051')
      self.stub = ontology_service_pb2_grpc.OntologyServiceStub(self.channel)
  
      def __del__(self):
      if self.channel != None:
      self.channel.close() # close grpc channel
  
      async def createOntology(self):
      return self.stub.CreateOntology(ontology_messages_pb2.Ontology())
  </code></pre>