Auto set logging filter (#8051)

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)
This commit is contained in:
Erik Johnston 2020-08-11 21:58:56 +01:00 committed by GitHub
commit 61d8ff0d44
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4 changed files with 17 additions and 21 deletions

1
changelog.d/8051.misc Normal file
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@ -0,0 +1 @@
It is no longer necessary to explicitly define `filters` in the logging configuration. (Continuing to do so is redundant but harmless.)

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@ -4,16 +4,10 @@ formatters:
precise:
format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
filters:
context:
(): synapse.logging.context.LoggingContextFilter
request: ""
handlers:
console:
class: logging.StreamHandler
formatter: precise
filters: [context]
loggers:
synapse.storage.SQL:

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@ -11,11 +11,6 @@ formatters:
precise:
format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
filters:
context:
(): synapse.logging.context.LoggingContextFilter
request: ""
handlers:
file:
class: logging.handlers.TimedRotatingFileHandler
@ -30,7 +25,6 @@ handlers:
# logs will still be flushed immediately.
buffer:
class: logging.handlers.MemoryHandler
filters: [context]
target: file
# The capacity is the number of log lines that are buffered before
# being written to disk. Increasing this will lead to better
@ -44,7 +38,6 @@ handlers:
console:
class: logging.StreamHandler
formatter: precise
filters: [context]
loggers:
synapse.storage.SQL:

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@ -55,11 +55,6 @@ formatters:
format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - \
%(request)s - %(message)s'
filters:
context:
(): synapse.logging.context.LoggingContextFilter
request: ""
handlers:
file:
class: logging.handlers.TimedRotatingFileHandler
@ -74,7 +69,6 @@ handlers:
# logs will still be flushed immediately.
buffer:
class: logging.handlers.MemoryHandler
filters: [context]
target: file
# The capacity is the number of log lines that are buffered before
# being written to disk. Increasing this will lead to better
@ -88,7 +82,6 @@ handlers:
console:
class: logging.StreamHandler
formatter: precise
filters: [context]
loggers:
synapse.storage.SQL:
@ -199,11 +192,26 @@ def _setup_stdlib_logging(config, log_config, logBeginner: LogBeginner):
handler = logging.StreamHandler()
handler.setFormatter(formatter)
handler.addFilter(LoggingContextFilter(request=""))
logger.addHandler(handler)
else:
logging.config.dictConfig(log_config)
# We add a log record factory that runs all messages through the
# LoggingContextFilter so that we get the context *at the time we log*
# rather than when we write to a handler. This can be done in config using
# filter options, but care must when using e.g. MemoryHandler to buffer
# writes.
log_filter = LoggingContextFilter(request="")
old_factory = logging.getLogRecordFactory()
def factory(*args, **kwargs):
record = old_factory(*args, **kwargs)
log_filter.filter(record)
return record
logging.setLogRecordFactory(factory)
# Route Twisted's native logging through to the standard library logging
# system.
observer = STDLibLogObserver()