added middleware to catch errors

etc/proxy-server.conf-sample

@@ -9,7 +9,7 @@
 # key_file = /etc/swift/proxy.key
 
 [pipeline:main]
-pipeline = healthcheck cache ratelimit auth proxy-server
+pipeline = catch_errors healthcheck cache ratelimit auth proxy-server
 
 [app:proxy-server]
 use = egg:swift#proxy
@@ -76,3 +76,6 @@ use = egg:swift#ratelimit
 # container_ratelimit_0 = 100
 # container_ratelimit_10 = 50
 # container_ratelimit_50 = 20
+
+[filter:cate_errors]
+use = egg:swift#catch_errors

setup.py

@@ -93,6 +93,7 @@ setup(
             'healthcheck=swift.common.middleware.healthcheck:filter_factory',
             'memcache=swift.common.middleware.memcache:filter_factory',
             'ratelimit=swift.common.middleware.ratelimit:filter_factory',
+            'catch_errors=swift.common.middleware.catch_errors:filter_factory',
             ],
         },
     )

swift/common/middleware/catch_errors.py

@@ -0,0 +1,48 @@
+# Copyright (c) 2010 OpenStack, LLC.
+#
+# 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.
+
+from webob import Request
+from webob.exc import HTTPServerError
+
+from swift.common.utils import get_logger
+
+
+class CatchErrorMiddleware(object):
+    """
+    Middleware that provides high-level error handling.
+    """
+
+    def __init__(self, app, conf):
+        self.app = app
+        self.logger = get_logger(conf)
+
+    def __call__(self, env, start_response):
+        try:
+            return self.app(env, start_response)
+        except Exception, err:
+            self.logger.exception('Error: %s' % err)
+            resp = HTTPServerError(request=Request(env),
+                                   body='An error occurred',
+                                   content_type='text/plain')
+            return resp(env, start_response)
+
+
+def filter_factory(global_conf, **local_conf):
+    conf = global_conf.copy()
+    conf.update(local_conf)
+    
+    def except_filter(app):
+        return CatchErrorMiddleware(app, conf)
+    return except_filter

test/unit/common/middleware/test_except.py

@@ -0,0 +1,49 @@
+# Copyright (c) 2010 OpenStack, LLC.
+#
+# 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 unittest
+
+from webob import Request
+
+from swift.common.middleware import catch_errors
+
+class FakeApp(object):
+    def __init__(self, error=False):
+        self.error = error
+
+    def __call__(self, env, start_response):
+        if self.error:
+            raise Exception('augh!')
+        return "FAKE APP"
+
+def start_response(*args):
+    pass
+
+class TestCatchErrors(unittest.TestCase):
+
+    def test_catcherrors_passthrough(self):
+        app = catch_errors.CatchErrorMiddleware(FakeApp(), {})
+        req = Request.blank('/', environ={'REQUEST_METHOD': 'GET'})
+        resp = app(req.environ, start_response)
+        self.assertEquals(resp, 'FAKE APP')
+
+    def test_catcherrors(self):
+        app = catch_errors.CatchErrorMiddleware(FakeApp(True), {})
+        req = Request.blank('/', environ={'REQUEST_METHOD': 'GET'})
+        resp = app(req.environ, start_response)
+        self.assertEquals(resp, ['An error occurred'])
+
+if __name__ == '__main__':
+    unittest.main()