I have a binary expression like the following:
up{instance=~"^.*:.*"} unless up{instance=~"^.*:10000$"}
It's just an example. I know that I could write regular expression so that it'll be just one. But it's a simplified example. Real dataset contains lot of series out of which I need to extract a subset and then filter out certain items.
I need to use the result of this expression (instant vector, right?) as one would use a typical instant vector - grab a range and feed to something like rate function for example. And it turns out that it's either not possible or I misunderstand some fundamental concept about PromQL.
How would one take a rate of the result of this expression?
UPDATE:
The following works:
rate(up{instance=~"^.*:.*"}[5m]) unless rate(up{instance=~"^.*:10000$"}[5m])
However, I was looking for a way to filter first and rate second, since otherwise a lot of rate processing will be done on series that will simply be dropped later.
Prometheus allows specifying multiple filters for the same label in a single series selector, then apply rate function to it - see this answer for details.
Prometheus allows passing arbitrary query results to functions, which accept e.g. range vectors, by using subqueries. For example, the following query would calculate arbitrary query q with 30-seconds interval between calculated points and then apply rate with 5 minutes lookbehind window over the calculated results:
rate((q)[5m:30s])
In general subqueries aren't recommended to use because they are hard to construct properly and because they may take too much cpu and memory to execute when improperly constructed.