Don't log exceptions when failing to fetch server keys

Not being able to resolve or connect to remote servers is an expected
error, so we shouldn't log at ERROR with stacktraces.

1 files changed, 6 insertions, 2 deletions

diff --git a/synapse/crypto/keyclient.py b/synapse/crypto/keyclient.py
index c20a32096a..e94400b8e2 100644
--- a/synapse/crypto/keyclient.py
+++ b/synapse/crypto/keyclient.py
@@ -18,7 +18,9 @@ import logging
 from canonicaljson import json
 
 from twisted.internet import defer, reactor
+from twisted.internet.error import ConnectError
 from twisted.internet.protocol import Factory
+from twisted.names.error import DomainError
 from twisted.web.http import HTTPClient
 
 from synapse.http.endpoint import matrix_federation_endpoint
@@ -47,12 +49,14 @@ def fetch_server_key(server_name, tls_client_options_factory, path=KEY_API_V1):
                 server_response, server_certificate = yield protocol.remote_key
                 defer.returnValue((server_response, server_certificate))
         except SynapseKeyClientError as e:
-            logger.exception("Error getting key for %r" % (server_name,))
+            logger.warn("Error getting key for %r: %s", server_name, e)
             if e.status.startswith("4"):
                 # Don't retry for 4xx responses.
                 raise IOError("Cannot get key for %r" % server_name)
+        except (ConnectError, DomainError) as e:
+            logger.warn("Error getting key for %r: %s", server_name, e)
         except Exception as e:
-            logger.exception(e)
+            logger.exception("Error getting key for %r", server_name)
     raise IOError("Cannot get key for %r" % server_name)