Limits metrics queries cardinality.

[cyriltovena]

With the new LogQL extensions we can now implicitly extract many labels.

Specially with logfmt and json.

We should add a way to via configuration:

• limit the maximum amount of labels per unique series and unique total series.

Questions ?

• Where should this be checked, within ingesters ? queriers ? frontend ? all of them ?

[owen-d]

I think you have to check them wherever we run parsers because the label set is only available after parsing.

I also think it'd be helpful to be able to specify a strategy at the query level such that you can either error the whole query or drop any offending lines (similar to using __error__ in logql). WDYT?

[cyriltovena]

I will start with errors for now, no dropping, we can do that later since I think it's more complex to craft.