[Proposal] Allow UTF8 string to be metric and label name

[viciss]

Proposal

For now, the metric and label name meets the regex expression [a-zA-Z_:][a-zA-Z0-9_:]*,
but sometimes it is not enough for some cases, like:

• 5xx_http_response to indicate a metric for all http response with 5xx error,
• Some non ASCII letters to be a metric name will be more meaningful for localization

So, would it be possible to extend the metric and label name to support UTF8 string?
Thanks!

[GiedriusS]

But where would we draw the line? Some symbols are obviously reserved e.g. { or }. For the first case I suggest adding the response code to the labels. The second one is a legit issue but IMHO I do not think that this should be done at the metrics level. Perhaps something on the top should translate the HELP strings.

[simonpasquier]

I'm closing this request as in the near future, Prometheus aims at being compliant with OpenMetrics which will be the source of truth for the exposition format.