Kubernetes Component SLI Metrics

FEATURE STATE: Kubernetes v1.29 [stable]

By default, Kubernetes 1.30 publishes Service Level Indicator (SLI) metrics for each Kubernetes component binary. This metric endpoint is exposed on the serving HTTPS port of each component, at the path /metrics/slis. The ComponentSLIs feature gate defaults to enabled for each Kubernetes component as of v1.27.

SLI Metrics

With SLI metrics enabled, each Kubernetes component exposes two metrics, labeled per healthcheck:

  • a gauge (which represents the current state of the healthcheck)
  • a counter (which records the cumulative counts observed for each healthcheck state)

You can use the metric information to calculate per-component availability statistics. For example, the API server checks the health of etcd. You can work out and report how available or unavailable etcd has been - as reported by its client, the API server.

The prometheus gauge data looks like this:

# HELP kubernetes_healthcheck [ALPHA] This metric records the result of a single healthcheck.
# TYPE kubernetes_healthcheck gauge
kubernetes_healthcheck{name="autoregister-completion",type="healthz"} 1
kubernetes_healthcheck{name="autoregister-completion",type="readyz"} 1
kubernetes_healthcheck{name="etcd",type="healthz"} 1
kubernetes_healthcheck{name="etcd",type="readyz"} 1
kubernetes_healthcheck{name="etcd-readiness",type="readyz"} 1
kubernetes_healthcheck{name="informer-sync",type="readyz"} 1
kubernetes_healthcheck{name="log",type="healthz"} 1
kubernetes_healthcheck{name="log",type="readyz"} 1
kubernetes_healthcheck{name="ping",type="healthz"} 1
kubernetes_healthcheck{name="ping",type="readyz"} 1

While the counter data looks like this:

# HELP kubernetes_healthchecks_total [ALPHA] This metric records the results of all healthcheck.
# TYPE kubernetes_healthchecks_total counter
kubernetes_healthchecks_total{name="autoregister-completion",status="error",type="readyz"} 1
kubernetes_healthchecks_total{name="autoregister-completion",status="success",type="healthz"} 15
kubernetes_healthchecks_total{name="autoregister-completion",status="success",type="readyz"} 14
kubernetes_healthchecks_total{name="etcd",status="success",type="healthz"} 15
kubernetes_healthchecks_total{name="etcd",status="success",type="readyz"} 15
kubernetes_healthchecks_total{name="etcd-readiness",status="success",type="readyz"} 15
kubernetes_healthchecks_total{name="informer-sync",status="error",type="readyz"} 1
kubernetes_healthchecks_total{name="informer-sync",status="success",type="readyz"} 14
kubernetes_healthchecks_total{name="log",status="success",type="healthz"} 15
kubernetes_healthchecks_total{name="log",status="success",type="readyz"} 15
kubernetes_healthchecks_total{name="ping",status="success",type="healthz"} 15
kubernetes_healthchecks_total{name="ping",status="success",type="readyz"} 15

Using this data

The component SLIs metrics endpoint is intended to be scraped at a high frequency. Scraping at a high frequency means that you end up with greater granularity of the gauge's signal, which can be then used to calculate SLOs. The /metrics/slis endpoint provides the raw data necessary to calculate an availability SLO for the respective Kubernetes component.

Last modified October 18, 2023 at 10:00 AM PST: update documentation for component-slis (53a8725ba7)