sample prometheus configuration explained

prometheus.yml

  // For all the confusing Prometheus configuration and
  // regular expressions,
  // explained in examples.


  // Remember, there are default values for each item if it's missing.
  // regex is (.*),
  // replacement is $1,
  // separator is ;
  // ,and action is replace 

  relabel_configs:
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scrape]
    action: keep
    regex: true
    // keep targets with label __meta_kubernetes_service_annotation_prometheus_io_scrape equals 'true',
    // which means the user added prometheus.io/scrape: true in the service's annotation.

  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scheme]
    action: replace
    target_label: __scheme__
    regex: (https?)
    // if __meta_kubernetes_service_annotation_prometheus_io_scheme is http or https, replace __scheme__ with its value that is the default replacement: $1.
    // this means the user added prometheus.io/scheme in the service's annotation.

  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_path]
    action: replace
    target_label: __metrics_path__
    regex: (.+)
    // this is also for service annotation of prometheus, if the user overrides the scrape path,
    // its value will be put in __metrics_path__

  - source_labels: [__address__, __meta_kubernetes_service_annotation_prometheus_io_port]
    action: replace
    target_label: __address__
    regex: (.+)(?::\d+);(\d+)
    replacement: $1:$2
    // if the user added prometheus.io/port in the service annotation,
    // use this port to replace the port in __address__

    // all above rules are for handling prometheus annotation: https://github.com/prometheus/prometheus/blob/master/documentation/examples/prometheus-kubernetes.yml

  - action: labelmap
    regex: __meta_kubernetes_service_label_(.+)
    // all __meta_kubernetes_service_label_(.+) will be changed to the (.+)
    // e.g. __meta_kubernetes_service_label_app='armada-api' to app='armada-api'

  - source_labels: [__meta_kubernetes_namespace]
    action: replace
    target_label: kubernetes_namespace
    // if __meta_kubernetes_namespace matches .*, put its value in label kubernetes_namespace

  - source_labels: [__meta_kubernetes_service_name]
    action: replace
    target_label: service_name
    // if __meta_kubernetes_service_name matches .*, put its value in label service_name

  - source_labels: [__meta_kubernetes_pod_node_name]
    action: replace
    target_label: hostname
    // if __meta_kubernetes_pod_node_name matches .*, put its value in label hostname

Thanks!

I am still confused... If I have a metric

some_metric{app="foo",baz="true"}
some_metric{app="bar",baz="true"}

How do I drop all baz labels and keep only app=foo metrics so that I end up with:

some_metric{app="foo"}

Also, what is separator? What am I separating? The only thing I can think of are labels, and I have never seen them separated by a ; which makes using it as the default very confusing.

@bschaeffer you can use labeldrop action to do it. for details https://medium.com/quiq-blog/prometheus-relabeling-tricks-6ae62c56cbda

for replace action , should the target label be already present / if its not present does prometheus add one ?

Amazing, made my day much easier, thanks!

thanks everyone, but really not in the mood to update this. i just got laid off by IBM :(

I'm so sad to heard this :( good luck

Thanks very useful when onboarding on Opentelemetry <3

Thanks this is helpful.

@nicocolt thanks. i am working at a start-up now, as an infra. engineer

Thanks very much!