Log unknown metrics from mcrouter

[filippog]

trafficstars

Hi, I'm in the process of updating the list of known metrics to mcrouter exporter compared to the upstream list. Since this is likely to happen in the future too it would be useful to log (e.g. at debug priority) which lines from stats all are not parsed/reported as metrics (IOW those lines are effectively unknown metrics). What do you think?

[Dev25]

That sounds like a good idea, either have it debug log on the first scrape or provide a --check like flag to just run a single scrape/log then exit.

[filippog]

I like the --check and looking at exit code idea! Would make it easy to run e.g. in CI across mcrouter versions to detect regressions.