# KubeAPIErrorBudgetBurn alert: what it means and how to fix it

What the KubeAPIErrorBudgetBurn Prometheus alert means, its common causes, the PromQL rule and the runbook steps to fix it, with a ready-to-use rule in YAML.

Last reviewed 2026-10-31

The Kubernetes API server is failing or slowing down requests fast enough to use up its error budget early. The rules use the multi-window burn-rate method from the Google SRE workbook against a 99% availability target. Each pairs a long and a short window, and both must exceed the threshold: 14.4 over 1h and 5m, and 6 over 6h and 30m, are critical; 3 over 1d and 2h, and 1 over 3d and 6h, are warnings. At a burn rate of 14.4 a 30-day error budget is gone in about two days. Controllers, kubectl and CI pipelines all go through the API server, so its errors spread everywhere.

* Part of the [Kubernetes alert rules](https://n9e.github.io/alert-rules/kubernetes.md) (`kubernetes.yml`)

## The rule[​](#the-rule "Direct link to The rule")

The template splits this alert into 4 rules with different thresholds, windows and severities. Load all of them together.

### KubeAPIErrorBudgetBurn-S1-120s[​](#kubeapierrorbudgetburn-s1-120s "Direct link to KubeAPIErrorBudgetBurn-S1-120s")

Critical (`critical`) · Fires after: 2m

```
sum(apiserver_request:burnrate1h) > (14.40 * 0.01000)

and

sum(apiserver_request:burnrate5m) > (14.40 * 0.01000)
```

### KubeAPIErrorBudgetBurn-S1-900s[​](#kubeapierrorbudgetburn-s1-900s "Direct link to KubeAPIErrorBudgetBurn-S1-900s")

Critical (`critical`) · Fires after: 15m

```
sum(apiserver_request:burnrate6h) > (6.00 * 0.01000)

and

sum(apiserver_request:burnrate30m) > (6.00 * 0.01000)
```

### KubeAPIErrorBudgetBurn-S2-3600s[​](#kubeapierrorbudgetburn-s2-3600s "Direct link to KubeAPIErrorBudgetBurn-S2-3600s")

Warning (`warning`) · Fires after: 60m

```
sum(apiserver_request:burnrate1d) > (3.00 * 0.01000)

and

sum(apiserver_request:burnrate2h) > (3.00 * 0.01000)
```

### KubeAPIErrorBudgetBurn-S2-10800s[​](#kubeapierrorbudgetburn-s2-10800s "Direct link to KubeAPIErrorBudgetBurn-S2-10800s")

Warning (`warning`) · Fires after: 180m

```
sum(apiserver_request:burnrate3d) > (1.00 * 0.01000)

and

sum(apiserver_request:burnrate6h) > (1.00 * 0.01000)
```

Alert message: `The API server is burning too much error budget.`

## Common causes[​](#common-causes "Direct link to Common causes")

* etcd is slow, most often because of disk latency, which drags down writes in particular.
* Clients issue expensive requests, such as LIST calls across all namespaces without a `resourceVersion`, which push latency past the SLO.
* An aggregated API (metrics-server, an admission webhook backend) is failing, and requests that depend on it fail with it.
* An admission webhook is slow or down, and every write it intercepts waits for it.
* The API server is short of CPU or memory, or one replica of several is unhealthy.

## How to fix it[​](#how-to-fix-it "Direct link to How to fix it")

1. Look at the apiserver error code and latency distribution to tell read from write degradation;
2. For write degradation, check etcd disk latency first — that is the most common root cause;
3. For read degradation, look for clients doing wide LIST calls (full enumeration without a resourceVersion);
4. Rate limit the offending client and consider enabling APF (API Priority and Fairness).

## Notes[​](#notes "Direct link to Notes")

* The expressions read the `apiserver_request:burnrate*` recording rules from kubernetes-mixin. Load those recording rules too, or the rules never fire.

## Metrics it uses[​](#metrics-it-uses "Direct link to Metrics it uses")

* `apiserver_request:burnrate1h` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate5m` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate6h` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate30m` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate1d` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate2h` (recording rule from kubernetes-mixin)
* `apiserver_request:burnrate3d` (recording rule from kubernetes-mixin)

## Related alerts[​](#related-alerts "Direct link to Related alerts")

* [KubeAPIDown](https://n9e.github.io/alert-rules/kubernetes.md#kubeapidown): KubeAPI has disappeared from Prometheus target discovery.
* [KubeClientErrors](https://n9e.github.io/alert-rules/kubernetes.md#kubeclienterrors): Kubernetes API server client '…/…' is experiencing … errors.'
* [KubeAggregatedAPIDown](https://n9e.github.io/alert-rules/kubernetes/kubeaggregatedapidown.md): Kubernetes aggregated API …/… has been only …% available over the last 10m.

## Prometheus rule YAML[​](#prometheus-rule-yaml "Direct link to Prometheus rule YAML")

Add this to a rules file loaded through `rule_files`, or download every Kubernetes rule at once as [`kubernetes.yml`](https://n9e.github.io/alert-rules/kubernetes.yml).

```
- alert: KubeAPIErrorBudgetBurn-S1-120s

  expr: |-

    sum(apiserver_request:burnrate1h) > (14.40 * 0.01000)

    and

    sum(apiserver_request:burnrate5m) > (14.40 * 0.01000)

  for: 2m

  labels:

    severity: critical

  annotations:

    summary: "The API server is burning too much error budget."

    runbook_url: "https://n9e.github.io/alert-rules/kubernetes/kubeapierrorbudgetburn"

- alert: KubeAPIErrorBudgetBurn-S1-900s

  expr: |-

    sum(apiserver_request:burnrate6h) > (6.00 * 0.01000)

    and

    sum(apiserver_request:burnrate30m) > (6.00 * 0.01000)

  for: 15m

  labels:

    severity: critical

  annotations:

    summary: "The API server is burning too much error budget."

    runbook_url: "https://n9e.github.io/alert-rules/kubernetes/kubeapierrorbudgetburn"

- alert: KubeAPIErrorBudgetBurn-S2-3600s

  expr: |-

    sum(apiserver_request:burnrate1d) > (3.00 * 0.01000)

    and

    sum(apiserver_request:burnrate2h) > (3.00 * 0.01000)

  for: 60m

  labels:

    severity: warning

  annotations:

    summary: "The API server is burning too much error budget."

    runbook_url: "https://n9e.github.io/alert-rules/kubernetes/kubeapierrorbudgetburn"

- alert: KubeAPIErrorBudgetBurn-S2-10800s

  expr: |-

    sum(apiserver_request:burnrate3d) > (1.00 * 0.01000)

    and

    sum(apiserver_request:burnrate6h) > (1.00 * 0.01000)

  for: 180m

  labels:

    severity: warning

  annotations:

    summary: "The API server is burning too much error budget."

    runbook_url: "https://n9e.github.io/alert-rules/kubernetes/kubeapierrorbudgetburn"
```

**With Nightingale**: this rule ships in the [Kubernetes integration](https://n9e.github.io/integrations/kubernetes.md) template; [import it into a business group](https://n9e.github.io/docs/data/integrations/import.md) and Nightingale attaches the runbook to every alert it sends.

## Sources and license[​](#sources-and-license "Direct link to Sources and license")

The rule expression is adapted from [kubernetes-mixin](https://github.com/kubernetes-monitoring/kubernetes-mixin) (Apache-2.0). The runbook steps come from [Nightingale's integration templates](https://github.com/ccfos/nightingale/tree/main/integrations) (Apache-2.0); the explanation and causes are written for this page.