Need to copy labels from metric1 to metric2

[Kishore Chopne]

Hi,

     If we have metric1{foo="1} and metric2{foo="1",bar="2"} ? How can I copy the labels from metric2 to metric1?  How can I create recording rules so that the new metrics can be sent to Prometheus.

The idea is to enrich some metrics with more labels.

Thanks.

/Kishore

[Brian Candler]

See:

https://www.robustperception.io/how-to-have-labels-for-machine-roles
https://www.robustperception.io/exposing-the-software-version-to-prometheus

https://prometheus.io/docs/prometheus/latest/querying/operators/#many-to-one-and-one-to-many-vector-matches

Assuming there are one or more instances of metric1 with label {foo="1"} and exactly one instance of metric2 with label {foo="1"}, then you can do:

metric1 * on (foo) group_left (bar) metric2

(I think that's right). metric1 is the "many" side and metric2 is the "one" side.  We can copy label bar from the "one" side to the "many" side.

[Kishore Chopne]

Thanks a lot Brian, it worked