Expand promlint rules

[csmarchbanks]

Proposal

Use case. Why is this important?

Right now there are prometheus naming best practices documented in both the docs and blog posts such as Robust Perception. I propose that as many of these conventions as possible should be codified in the promtool check metrics tool.

Currently the promlint code includes rules for:

• Help text
• Using base units
• Using misleading/inappropriate suffixes

I propose that in addition there should be rules for:

• Don't put the metric type in the name, such as request_duration_seconds_histogram
• Don't use colons in metric names (reserved for recording rules)
• Use snake_case not camelCase
• Detection on _s_ instead of seconds, _b_ or _kb_ instead of _bytes_

I would love to hear other people's opinion on rules that should be added and am happy to change the list around.

If people think some or all of these new rules are a good idea I plan to do the implementation.

Thanks for thinking about this proposal!