Handle 500 errors coming from nova

We do not want to return the nova error 500 messages to the users but
rather build our own message, so that a bug is filled to us.

Change-Id: Iaeae2affdb60f22df64fd1929e3bd8c18ac3e64c
Closes-bug: #1624233

ooi/api/helpers.py

@@ -88,16 +88,26 @@ def exception_from_response(response):
         501: webob.exc.HTTPNotImplemented,
         503: webob.exc.HTTPServiceUnavailable,
     }
+
+    message = ('Unexpected API Error. Please report this at '
+               'http://bugs.launchpad.net/ooi/ and attach the ooi '
+               'API log if possible.')
+
     code = response.status_int
     exc = exceptions.get(code, webob.exc.HTTPInternalServerError)
-    try:
-        message = response.json_body.popitem()[1].get("message")
-        exc = exc(explanation=message)
-    except Exception:
-        LOG.exception("Unknown error happenened processing response %s"
-                      % response)
-        return webob.exc.HTTPInternalServerError()
-    return exc
+
+    if code in exceptions:
+        try:
+            message = response.json_body.popitem()[1].get("message")
+        except Exception:
+            LOG.exception("Unknown error happenened processing response %s"
+                          % response)
+            exc = webob.exc.HTTPInternalServerError
+    else:
+        LOG.error("Nova returned an internal server error %s"
+                  % response)
+
+    return exc(explanation=message)
 
 
 class BaseHelper(object):

ooi/tests/unit/controllers/test_helpers.py

@@ -114,9 +114,6 @@ class TestExceptionHelper(base.TestCase):
             429: webob.exc.HTTPTooManyRequests,
             501: webob.exc.HTTPNotImplemented,
             503: webob.exc.HTTPServiceUnavailable,
-            # Any other thing should be a 500
-            500: webob.exc.HTTPInternalServerError,
-            507: webob.exc.HTTPInternalServerError,
         }
 
         for code, exception in six.iteritems(code_and_exception):
@@ -126,6 +123,23 @@ class TestExceptionHelper(base.TestCase):
             self.assertIsInstance(ret, exception)
             self.assertEqual(fault["computeFault"]["message"], ret.explanation)
 
+    def test_unexpected_exception(self):
+        code_and_exception = {
+            500: webob.exc.HTTPInternalServerError,
+            # Any other thing should be a 500
+            507: webob.exc.HTTPInternalServerError,
+        }
+        message = ("Unexpected API Error. Please report this at "
+                   "http://bugs.launchpad.net/ooi/ and attach the "
+                   "ooi API log if possible.")
+
+        for code, exception in six.iteritems(code_and_exception):
+            fault = self.get_fault(code)
+            resp = fakes.create_fake_json_resp(fault, code)
+            ret = helpers.exception_from_response(resp)
+            self.assertIsInstance(ret, exception)
+            self.assertEqual(message, ret.explanation)
+
     def test_error_handling_exception(self):
         fault = {}
         resp = fakes.create_fake_json_resp(fault, 404)