Raise NotFoundException for 404s

We need to provide better exceptions on top of 404s, so rather than
having multiple places in Resources or Proxies checkout
HttpException.status_code, we should capture that early and raise this
more specific exception.

Change-Id: I4b50f54bc6236fecb4b9262417259fd32a2bcd65

openstack/exceptions.py

@@ -75,6 +75,11 @@ class HttpException(SDKException):
         return self.__unicode__()
 
 
+class NotFoundException(HttpException):
+    """HTTP 404 Not Found."""
+    pass
+
+
 class MethodNotSupported(SDKException):
     """The resource does not support this operation type."""
     pass

openstack/tests/test_transport.py

@@ -273,7 +273,7 @@ class TestTransport(base.TestTransportBase):
         status = 404
         self.stub_url(httpretty.GET, status=status)
 
-        exc = self.assertRaises(exceptions.HttpException, xport.get,
+        exc = self.assertRaises(exceptions.NotFoundException, xport.get,
                                 self.TEST_URL)
         self.assertEqual(status, exc.status_code)
 

openstack/transport.py

@@ -262,10 +262,15 @@ class Transport(requests.Session):
         try:
             resp.raise_for_status()
         except requests.RequestException as e:
-            raise exceptions.HttpException(
-                six.text_type(e),
-                details=self._parse_error_response(resp),
-                status_code=resp.status_code)
+            if resp.status_code == 404:
+                exc_type = exceptions.NotFoundException
+            else:
+                exc_type = exceptions.HttpException
+
+            raise exc_type(six.text_type(e),
+                           details=self._parse_error_response(resp),
+                           status_code=resp.status_code)
+
         if accept == JSON:
             try:
                 resp.body = resp.json()