Great question wheresh. I had the exact same question too. And I was extremely confused.
I think (please someone correct me if I'm wrong) that the action *labelmap* actually creates a new set of labels, instead of relabeling the labels: * https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config* * "labelmap: Match regex against all label names. Then copy the values of the matching labels to label names given by replacement..."* Also, I think that *labelmap* is not a replace action because all replace actions require a target_label: * https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config* * # Label to which the resulting value is written in a replace action. * * # It is mandatory for replace actions. Regex capture groups are available. * * [ target_label: <labelname> ]* So I think it just creates a new set of labels. The default replacement is $1, and in the example what is being captured in "regex: __meta_kubernetes_service_label_(.+)" is the very last part. So this is what I think is happening: *Labels that were matched New Labels* _meta_kubernetes_service_label_somelabel1 -> somelabel1 _meta_kubernetes_service_label_somelabel2 -> somelabel2 _meta_kubernetes_service_label_somelabel3 -> somelabel3 _meta_kubernetes_service_label_somelabel4 -> somelabel4 _meta_kubernetes_service_label_somelabel5 -> somelabel5 Someone please either confirm that this is what is happening, or provide an explanation of what is actually happening. Thank you! On Tuesday, January 9, 2018 at 10:49:14 PM UTC-8 [email protected] wrote: > hi, I check the demo yml file and found this : > > - action: labelmap regex: __meta_kubernetes_service_label_(.+) - >> source_labels: [__meta_kubernetes_namespace] action: replace target_label: >> kubernetes_namespace > > seems no target_label to replace in the action labelmap . > then what happens to it ? > > 在 2017年5月3日星期三 UTC+8上午7:16:51，Julius Volz写道： >> >> "labelmap" maps a whole set of labels (that match a regex) over to the >> target labels. That's typically useful if you want to copy over a whole set >> of labels (like all starting with "__meta_kubernetes_service_label_") to >> the target's labels. For example: >> https://github.com/prometheus/prometheus/blob/86426c05669417cf1012fbc3a40fb7e0f5a8a101/documentation/examples/prometheus-kubernetes.yml#L113-L114 >> >> "replace" does a replacement of a single label only (possibly from >> multiple source labels). Thus you can't use "replace" to copy over an >> arbitrary number of labels (of which you possibly don't know all exact >> names), but only one per relabeling rule. >> > On Wed, May 3, 2017 at 12:57 AM, Cemalettin Koc <[email protected]> >> wrote: >> > I have some confusion regarding labelmap and replace usage in scrape >>> configuration. I think that they can be used for each other. >>> >>> 1. What is the difference between them? For which use cases they are >>> more suitable? >>> 2. "replace" is using "target_label" whereas "labelmap" is using >>> "replacement" for targeting. Why is not labelmap using "target_label" as >>> well? >>> >>> Thanks >>> >> -- >>> You received this message because you are subscribed to the Google >>> Groups "Prometheus Users" group. >>> >> To unsubscribe from this group and stop receiving emails from it, send an >>> email to [email protected]. >>> To post to this group, send email to [email protected]. >> >> >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/prometheus-users/37905bb7-539c-4f85-9231-2fe4849bde9a%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/prometheus-users/37905bb7-539c-4f85-9231-2fe4849bde9a%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- You received this message because you are subscribed to the Google Groups "Prometheus Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/prometheus-users/da95e93a-ba17-4bc0-9275-573c4ee5aa6en%40googlegroups.com.
