logging should put all errors in homeserver.log

[sbts]

If the client can't be found synapse fails and reports

Could not find webclient

on the console.
However nothing is reported in homeserver.log except info messages, and they all appear to be normal and expected.

Specifically this occurs on the debian package 0.18.5-1 but I'd expect it to be a general issue.

The same problem also occurs if twisted can't listen on a port (eg: 443)

twisted.internet.error.CannotListenError: Couldn't listen on any:443: [Errno 13] Permission denied.

Appears on the console, but nothing in the logs

[sbts]

When run from systemd it is possible to retrieve the console output from a service by running

journalctl -u matrix-synapse -b -e

[richvdh]

There are a few errors that happen while we're reading the configuration, which happens before we set up the logging. The solution to that is probably to configure the logger to send all logs to stdout and have journald manage the logs.

Related: #1539 (comment)

[richvdh]

It's worth noting that both the cases in the original report are now fixed:

• synapse does not expose a web client by default, but if it is enabled and the webclient cannot be found, a warning is written to the logs (fixed in Stop installing Matrix Console by default #4290)
• if we cannot bind to a port, we write an error to the logs and the console (fixed in Clean up exception handling in the startup code #9059), before exiting.

There still remains a class of warnings that are written before the logging is set up - typically these are deprecation warnings etc. We could stack these up until the logging is configured, and write copies to the logs as well/instead, but I'm not entirely sure this is necessary.

[richvdh]

I think this is probably as fixed as it's going to be. Logging errors that happen before the logger is set up is hard.