Follow up to 160ae2d
Analysis by @dcf,
> I don't think the sync.Once around logMetrics is necessary anymore.
Its original purpose was to inhibit logging on later file handles of
metrics.log, if there were more than one opened. See 171c55a9 and #29734
(comment 2593039) "Making a singleton *Metrics variable causes problems
with how Convey does tests. It shouldn't be called more than once, but
for now I'm using sync.Once on the logging at least so it's explicit."
Commit ba4fe1a7 changed it so that metrics.log is opened in main, used
to create a *log.Logger, and that same instance of *log.Logger is passed
to both NewMetrics and NewBrokerContext. It's safe to share the same
*log.Logger across multiple BrokerContext.
Doesn't seem like it needs to exist outside of the metrics struct.
Also, the call to logMetrics is moved to the constructor. A metrics
instance is only created when a BrokerContext is created, which only
happens at startup. The sync of only doing that once is left for
documentation purposes, since it doesn't hurt, but also seems redundant.
The default prometheus registry exports data that may be useful for
side-channel attacks. This removes all of the default metrics and makes
sure we are only reporting snowflake metrics from the broker.
This change adds a prometheus exporter for our existing snowflake broker
metrics. Current values for the metrics can be fetched by sending a GET
request to /prometheus.
We currently don't sort the snowflake-ips metrics:
snowflake-ips CA=1,DE=1,AR=1,NL=1,FR=1,GB=2,US=4,CH=1
To facilitate eyeballing our metrics, this patch sorts snowflake-ips by
value. If the value is identical, we sort by string, i.e.:
snowflake-ips US=4,GB=2,AR=1,CA=1,CH=1,DE=1,FR=1,NL=1
This patch fixes tpo/anti-censorship/pluggable-transports/snowflake#40011
As we now partition proxies by NAT type, our stats are more useful if they
capture how many proxies of each type we have, and information on
whether we have enough proxies of the right NAT type for our clients.
This change adds proxy counts by NAT type and binned counts of denied clients by NAT type.
Added another lock to the metrics struct to synchronize accesses to the
broker stats. There's a possible race condition if stats are updated at
the same time they are being logged.
Many of our log messages were being used to generate metrics, but are
now being aggregated and logged to a separate metrics log file and so we
don't need them in the regular logs anymore.
This addresses the goal of ticket #30830, to remove unecessary messages
and keep broker logs for debugging purposes.
Added three new metrics:
- proxyIdleCount counts the number of times a proxy polls and receives
no snowflakes
- clientDeniedCount counts the number of times a client requested a
snowflake but none were available
- clientProxyMatchCount counts the number of times a client successfully
received a snowflake
Previously the metrics log file was hardcoded and the broker wasn't
behaving properly if it was unable to open the file for logging.
Added a commandline option to specify the logfile that defaults to
Stdout.
Fixed up some documentation and log output formatting
