> I mean, what if we consider a metricId also opaque, and we know that in P8S
> is a combination of <metric_name><labels>, at the end of the day, is a
> string and it is unique.
>
> I ask this, because if we expose the details, it will be tempted to start
> manipulating IDs in other layers, and perhaps that will create technical
> debt.

Just thinking off the top of my head, Prometheus's "family{labels}" ID is not to be considered opaque. It is important, I think, that clients understand these because it is how you query in Prometheus.

For example, to get a group (aggregate) metric value, you could query on just a subset of labels thus aggregating over the labels you did not specify.

For example, if there is:

http_requests_time{method="POST", app="my.war"} = 1.0
http_requests_time{method="POST", app="another.war"} = 1.2
http_requests_time{method="GET", app="my.war"} = 0.5
http_requests_time{method="GET", app="another.war"} = 0.6

A client (MiQ UI?) can aggregate the GET request times across all apps by
knowing it only queries with the method label, like "average( http_requests_time{method="GET"} )"

So therefore P metric IDs (family+labels) are not opaque - clients need to understand them a bit.