* Change default log config to buffer by default.
This batches up writes to the filesystem, which is more efficient for
disk I/O. This means that it can take some time for logs to get written
to disk. Note that ERROR logs (and above) immediately flush the buffer.
This only effects new installs, as we only write the log config if
started with `--generate-config` (in the same way we do for generating
signing keys).
* Default to keeping last 4 days of logs.
This hopefully reduces the amount of logs kept for new servers. Keeping
the last 1GB of logs is likely overkill for new servers, but equally may
not be enough for busy ones.
Instead, we keep the last four days worth of logs, enough so that admins
can investigate any problems that happened over e.g. a long weekend.
Turns out that loggers that are instantiated before the config is loaded get
turned off.
Also bring the logging config that is generated by --generate-config into line.
Fixes#6194.
The general idea here is that config examples should just have a hash and no
extraneous whitespace, both to make it easier for people who don't understand
yaml, and to make the examples stand out from the comments.
* Better logging for errors on startup
* Fix "TypeError: '>' not supported" when starting without an existing
certificate
* Fix a bug where an existing certificate would be reprovisoned every day
... because these only really exist to confuse people nowadays.
Also bring log config more into line with the generated log config, by making `level_for_storage`
apply to the `synapse.storage.SQL` logger rather than `synapse.storage`.
The debug 'full_twisted_stacktraces' flag caused synapse to rewrite
twisted deferreds to always fire the callback on the next reactor tick.
This was to force the deferred to always store the stacktraces on
exceptions, and thus be more likely to have a full stacktrace when it
reaches the final error handlers and gets printed to the logs.
Dynamically rewriting things is generally bad, and in particular this
change violates assumptions of various bits of Twisted. This wouldn't
necessarily be so bad, but it turns out this option has been turned on
on some production servers.
Turning the option can cause e.g. #1778.
For now, lets just entirely nuke this option.
