Middleware to catch all error in WSGI pipeline

Change-Id: I6214b48923efe765dc87bc143fbb346efd0b17b3

2 files changed, 90 insertions, 0 deletions

diff --git a/openstack/common/middleware/catch_errors.py b/openstack/common/middleware/catch_errors.py
new file mode 100644
index 0000000..4de4120
--- /dev/null
+++ b/openstack/common/middleware/catch_errors.py
@@ -0,0 +1,43 @@
+# Copyright (c) 2013 NEC Corporation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Middleware that provides high-level error handling.
+
+It catches all exceptions from subsequent applications in WSGI pipeline
+to hide internal errors from API response.
+"""
+
+import webob.dec
+import webob.exc
+
+from openstack.common.gettextutils import _  # noqa
+from openstack.common import log as logging
+from openstack.common.middleware import base
+
+
+LOG = logging.getLogger(__name__)
+
+
+class CatchErrorsMiddleware(base.Middleware):
+
+    @webob.dec.wsgify
+    def __call__(self, req):
+        try:
+            response = req.get_response(self.application)
+        except Exception:
+            LOG.exception(_('An error occurred during '
+                            'processing the request: %s'))
+            response = webob.exc.HTTPInternalServerError()
+        return response
diff --git a/tests/unit/middleware/test_catch_errors.py b/tests/unit/middleware/test_catch_errors.py
new file mode 100644
index 0000000..476ae24
--- /dev/null
+++ b/tests/unit/middleware/test_catch_errors.py
@@ -0,0 +1,47 @@
+# Copyright (c) 2013 NEC Corporation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import mock
+import webob.dec
+import webob.exc
+
+from openstack.common.middleware import catch_errors
+from openstack.common import test
+
+
+class CatchErrorsTest(test.BaseTestCase):
+
+    def _test_has_request_id(self, application, expected_code=None):
+        app = catch_errors.CatchErrorsMiddleware(application)
+        req = webob.Request.blank('/test')
+        res = req.get_response(app)
+        self.assertEqual(expected_code, res.status_int)
+
+    def test_success_response(self):
+        @webob.dec.wsgify
+        def application(req):
+            return 'Hello, World!!!'
+
+        self._test_has_request_id(application, webob.exc.HTTPOk.code)
+
+    def test_internal_server_error(self):
+        @webob.dec.wsgify
+        def application(req):
+            raise Exception()
+
+        with mock.patch.object(catch_errors.LOG, 'exception') as log_exc:
+            self._test_has_request_id(application,
+                                      webob.exc.HTTPInternalServerError.code)
+            self.assertEqual(1, log_exc.call_count)