This modifies the configuration of structured logging to be usable from
the standard Python logging configuration.
This also separates the formatting of logs from the transport allowing
JSON logs to files or standard logs to sockets.
We do this to prevent foot guns. The default config uses a MemoryFilter,
but users are free to change to logging to files directly. If they do
then they have to ensure to set the `filters: [context]` on the right
handler, otherwise records get written with the wrong context.
Instead we move the logic to happen when we generate a record, which is
when we *log* rather than *handle*.
(It's possible to add filters to loggers in the config, however they
don't apply to descendant loggers and so they have to be manually set on
*every* logger used in the code base)
* 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`.
Patrick Cloke