fixup! Fix: Frequent timeouts from TDR (#7452)

Author: dsotirho-ucsc

src/azul/chalice.py

@@ -265,21 +265,26 @@ def _security_headers_middleware(self, event, get_response):
 
     def _retry_after(self, event, get_response):
         """
-        Add a retry-after header to the response based on the response type.
+        Add a retry-after header to the response based on its type.
         """
         response = get_response(event)
         status = response.status_code
-        if status in [307, 503]:
+        if status == 503:
             response.headers.setdefault('Retry-After', '30')
-        if status == 307:
-            # When a client's request fails due to an internal request to TDR
-            # timing out, we want the client to retry their request, so we
-            # return a 307 response along with a location header containing the
-            # URL the client had just requested.
-            location = furl(self.base_url,
-                            path=event.context['path'],
-                            args=event.query_params)
-            response.headers.setdefault('Location', location.url)
+        elif status == 307:
+            response.headers.setdefault('Retry-After', '5')
+            # When a client's request fails due to an internal request to Terra
+            # timing out, instead of returning a 503 which causes the Data
+            # Browser to show an error and also raises CloudWatch alarm, we
+            # return a 307 to indicate the client should retry their request.
+            if 'Location' not in response.headers:
+                if event.query_params is None:
+                    args = None
+                else:
+                    assert isinstance(event.query_params, MultiDict)
+                    args = {k: event.query_params.getlist(k) for k in event.query_params}
+                url = furl(self.base_url, path=event.context['path'], args=args)
+                response.headers['Location'] = str(url)
         return response
 
     def _http_cache_for(self, seconds: int):