Prometheus Query to aggregate metrics by certain label values

Question

I have my metrics exposed by Prometheus as:

custom_metric{label1="abc", label2="xyz"} num1
custom_metric{label1="def", label2="uvw"} num2
custom_metric{label1="ghi", label2="rst"} num3
custom_metric{label1="jkl", label2="opq"} num4

I want to query the metric such that I get sum of metric for label1="abc" , label1="def" and label1="jkl" .

I expect the result after querying to be something on lines of custom_metric_groupped (num1 + num2 + num4) .

Another thing, in my use case, the number of specific label values can vary. So, it might be the case that in future I might want to only take the sum for label1="def" and label1="jkl"

Answer 1

Try the following query:

sum(custom_metric{label1=~"abc|def|jkl"})

It works in the following way:

1. It selects time series matching label selector custom_metric{label1=~"abc|def|jkl"} - see these docs . Note that the required values for the label1 are enumerated in the regexp filter with | delimiter.
2. It sums values for the selected time series individually per each requested timestamp (aka point on the graph) via sum aggregate function.