kube-metrics-adapter/how-to/skipper_setup.md

Skipper Prometheus Metrics Collection

The skipper-ingress pods should be configured to be scraped by Prometheus. This can be done by Prometheus service discovery using discovery of Kubernetes services or Kubernetes pods:

apiVersion: v1
kind: Service
metadata:
  annotations:
    prometheus.io/path: /metrics
    prometheus.io/port: "9911"
    prometheus.io/scrape: "true"
  labels:
    application: skipper-ingress
  name: skipper-ingress
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 9999
  selector:
    application: skipper-ingress
  type: ClusterIP

This configuration shows how prometheus is configured in our clusters to scrape service endpoints. The annotations prometheus.io/path, prometheus.io/port and prometheus.io/scrape instruct Prometheus to scrape all pods of this service on the port 9911 and the path /metrics.

When the kube-metrics-adapter is started the flag --prometheus-server should be set so that the adapter can query prometheus to get aggregated metrics. When running in kubernetes it can be the service address of the prometheus service like http://prometheus.kube-system.

With these settings the kube-metrics-adapter can provide request-per-second metrics for ingress objects which are present in the cluster. The prometheus instances scrape the metrics from the skipper-ingress pods. The adapter then queries prometheus to get the metric and then provides them to the API server when requested.