Merge pull request #3727 from matrix-org/erikj/dont_error_on_missing_keys

Don't log exceptions when failing to fetch server keys

changelog.d/3727.misc

@@ -0,0 +1 @@
+Log failure to authenticate remote servers as warnings (without stack traces)

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)
 
 

synapse/federation/transport/server.py

@@ -261,10 +261,10 @@ class BaseFederationServlet(object):
             except NoAuthenticationError:
                 origin = None
                 if self.REQUIRE_AUTH:
-                    logger.exception("authenticate_request failed")
+                    logger.warn("authenticate_request failed: missing authentication")
                     raise
-            except Exception:
-                logger.exception("authenticate_request failed")
+            except Exception as e:
+                logger.warn("authenticate_request failed: %s", e)
                 raise
 
             if origin: