Kubernetes Component SLI Metrics
Kubernetes v1.29 [stable]
By default, Kubernetes 1.31 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.