nsqd: ability to skip ephemeral topics/channels in statsd output

[jehiah]

When using nsqd with statsd/graphite ephemeral topics and channels can dramatically increase the number of datasets on the graphite side. This creates an option to filter out those from being written to graphite)

I thought this was existing behaviour but discovered this issue due to a new usage pattern that used a dynamic and frequently changing ephemeral channel name. In my case the # was being stripped out of key names and so I had missinterpreted missing graphs in nsqadmin for ephemeral channels as no data in graphite, when it was actually a missmatch between the query and resulting dataset key.

To provide a way to filter out ephemeral topics and channels this adds a new --statsd-exclude-ephemeral argument which defaults to false (existing behavior).

[ploxiln]

the # was being stripped out of key names and so I had missinterpreted missing graphs in nsqadmin

Is this a bug in nsqd/nsqadmin, should we also try to fix this? (separately would be fine)

[jehiah]

the # was being stripped out of key names and so I had missinterpreted missing graphs in nsqadmin

Is this a bug in nsqd/nsqadmin, should we also try to fix this? (separately would be fine)

It looks like this is happening in bitly/statsdaemon (i'm not positive what other statsd implementations do) so it does seem reasonable to match that behavior in nsqadmin by default (i'll do that separately).

https://github.com/bitly/statsdaemon/blob/fc46d9cfe29b674a0c8abc723afaa9370430cdcd/statsdaemon.go#L64-L88