Metrics in Kubernetes

Internal

• Kubernetes Resource Management Concepts
• Kubernetes Concepts

Metrics

Resource Metrics

A resource metric is a numeric quantity that tracks either the CPU or memory consumed by containers and pods. By default, the only two supported resource metrics are the CPU utilization and the memory consumed by a container. These resources do not change names from cluster to cluster and they should be available as long the Resource Metrics API is available.

Resource Metrics API

metrics.k8s.io TODO:

• https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/resource-metrics-api.md
• https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/custom-metrics-api.md

Custom Metrics

Aside from resource metrics, there are two other types of metrics, both of which are considered custom metrics: pod metrics and object metrics.

Pod Metrics

These resource describe pods.

Object Metrics

These resources describe different objects in the same namespace, instead of describing pods.

Custom Metrics API

custom.metrics.k8s.io

Monitoring systems like Prometheus expose application-specific metrics to the Horizontal Pod Autoscaler controller via the Custom Metrics API.

External Metrics

External Metrics API

external.metrics.k8s.io

Kubernetes Metrics Server

Kubernetes Metrics Server

Notes

• More details about resource metrics API.
• Metrics: raw values, utilization values.
• Metric server: https://kubernetes.io/docs/tasks/debug-application-cluster/resource-metrics-pipeline/, https://github.com/kubernetes-sigs/metrics-server
• Custom metrics API: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/custom-metrics-api.md
• External metrics API: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/external-metrics-api.md