Collect and view kube state metrics

This page describes how to configure a Google Kubernetes Engine (GKE) cluster to send a curated set of kube state, including metrics for Pods and Deployments, Cloud Monitoring using Google Cloud Managed Service for Prometheus. This page also describes how these metrics are formatted when they are written to Monitoring, and how to query metrics.

Before you begin

Before you start, make sure you have performed the following tasks:

  • Enable the Google Kubernetes Engine API.
    • Enable Google Kubernetes Engine API
  • If you want to use the Google Cloud CLI for this task, install and then initialize the gcloud CLI. If you previously installed the gcloud CLI, get the latest version by running gcloud components update.

Requirements

To collect kube state metrics, your GKE cluster must meet the following requirements:

  • The cluster must be running GKE 1.27.2-gke.1200 or later. For GKE Standard clusters starting with version 1.29.2-gke.2000 and GKE Autopilot clusters starting with version 1.27.4-gke.900, the Kube state metrics package is enabled by default.
  • The cluster must have system metrics enabled.
  • The cluster must have Google Cloud Managed Service for Prometheus managed collection enabled. Google Cloud Managed Service for Prometheus managed collection is enabled by default for new clusters.

Configure the collection of kube state metrics

You can enable kube state metrics using the Google Cloud console, the gcloud CLI, or Terraform:

Console

You can enable kube state metrics from the Observability tab for either a cluster or a Deployment within a cluster. You can also preview the available charts and metrics before you enable the metric package.

On the Observability tab for a cluster, you can filter the set of charts for kube state metrics by the following two items:

  • Workloads State: includes the metrics for Pods, Deployments, StatefulSets, DaemonSets, and HorizontalPodAutoscaler resources.
  • Storage > Persistent: includes the metrics for Persistent Volumes and Persistent Volume Claims.

You can enable either or both sets of metrics.

To enable kube state metrics from the Observability tab for a cluster, do the following:

  1. In the Google Cloud console, go to the Kubernetes clusters page:

    Go to Kubernetes clusters

    If you use the search bar to find this page, then select the result whose subheading is Kubernetes Engine.

  2. Click your cluster's name and then select the Observability tab.

  3. Select either Workloads State or Storage > Persistent from the list of features.

  4. Click Enable package.

    If the kube state metrics package is already enabled, then you see a set of charts for kube state metrics instead.

To enable kube state metrics from the Observability tab for a Deployment, do the following:

  1. In the Google Cloud console, go to the Workloads page:

    Go to Workloads

    If you use the search bar to find this page, then select the result whose subheading is Kubernetes Engine.

  2. Click the name of your Deployment and then select the Observability tab.

  3. Select Kube State from the list of features.

  4. Click Enable package. The package is enabled for the entire cluster.

    If the kube state metrics package is already enabled, then you see a set of charts for metrics from Pods, Deployments, and Horizontal Pod Autoscalers.

To configure kube state metrics from the Details tab for the cluster, do the following:

  1. In the Google Cloud console, go to the Kubernetes clusters page:

    Go to Kubernetes clusters

    If you use the search bar to find this page, then select the result whose subheading is Kubernetes Engine.

  2. Click your cluster's name.

  3. In the Features row labelled Cloud Monitoring, click the Edit icon.

  4. In the Edit Cloud Monitoring dialog that appears, confirm that Enable Cloud Monitoring is selected.

  5. In the Components drop-down menu, select the kube state components from which you want to collect metrics.

  6. Click OK.

  7. Click Save Changes.

gcloud

Update your cluster to collect metrics:

gcloud container clusters update CLUSTER_NAME \
    --location=COMPUTE_LOCATION \
    --enable-managed-prometheus \
    --monitoring=METRICS_LIST

Replace the following:

  • CLUSTER_NAME: the name of the existing cluster.
  • COMPUTE_LOCATION: the Compute Engine location of the cluster.
  • METRICS_LIST: a comma-separated list of metrics, which can include any of the following:
    • DAEMONSET
    • DEPLOYMENT
    • HPA
    • POD
    • STATEFULSET
    • STORAGE: metrics for Persistent Volume and Persistent Volume Claims.

The set of values supplied to the monitoring flag overrides any previous setting.

Terraform

To configure the collection of kube state metrics by using Terraform, see the monitoring_config block in the Terraform registry for google_container_cluster. For general information about using Google Cloud with Terraform, see Terraform with Google Cloud.

Quota

Kube state metrics consume the Time series ingestion requests per minute quota of the Cloud Monitoring API. Before enabling kube state metrics, check your recent peak usage of that quota. If you have many clusters in the same project or are already approaching that quota limit, you can request a quota limit increase before enabling either observability package.

Pricing

Kube state metrics use Google Cloud Managed Service for Prometheus to load metrics into Cloud Monitoring. Cloud Monitoring charges for the ingestion of these metrics are based on the number of samples ingested. However, these metrics are free-of-charge for the registered clusters that belong to a project that has GKE Enterprise edition enabled.

For more information, see Cloud Monitoring pricing.

Metric format

All Kubernetes kube state metrics written to Cloud Monitoring use the resource type prometheus_target. Each metric name is prefixed with prometheus.googleapis.com/ and has a suffix indicating the Prometheus metric type, such as /gauge, /histogram, or /counter. Otherwise, each metric name is identical to the metric name exposed by open source Kubernetes.

Exporting from Cloud Monitoring

The kube state metrics can be exported from Cloud Monitoring by using the Cloud Monitoring API. Because all kube state metrics are ingested by using Google Cloud Managed Service for Prometheus, kube state metrics can be queried by using Prometheus Query Language (PromQL). They can also be queried by using by using Monitoring Query Language (MQL).

Querying metrics

When you query kube state metrics, the name you use depends on whether you are using PromQL or Cloud Monitoring-based features like MQL or the Metrics Explorer menu-driven interface.

The following tables of kube state metrics show two versions of each metric name:

  • PromQL metric name: When using PromQL in Cloud Monitoring pages of the Google Cloud console or in PromQL fields of the Cloud Monitoring API, use the PromQL metric name.
  • Cloud Monitoring metric name When using other Cloud Monitoring features, use the Cloud Monitoring metric name in the tables below. This name must be prefixed with prometheus.googleapis.com/, which has been omitted from the entries in the table.

Storage metrics

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_persistentvolume_capacity_bytes
kube_persistentvolume_capacity_bytes/gauge
GAUGE, DOUBLE, By
prometheus_target
1.27.2-gke.1200 		Persistentvolume capacity in bytes. Sampled every 30 seconds.

persistentvolume: persistentvolume.
kube_persistentvolume_claim_ref
kube_persistentvolume_claim_ref/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Information about the Persistent Volume Claim Reference. Sampled every 30 seconds.

claim_name: claim_name.
name: name.
persistentvolume: persistentvolume.
kube_persistentvolume_info
kube_persistentvolume_info/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Information about persistentvolume. Sampled every 30 seconds.

csi_driver: csi_driver.
csi_volume_handle: csi_volume_handle.
local_fs: local_fs.
local_path: local_path.
persistentvolume: persistentvolume.
storageclass: storageclass.
kube_persistentvolume_status_phase
kube_persistentvolume_status_phase/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The phase indicates if a volume is available, bound to a claim, or released by a claim. Sampled every 30 seconds.

persistentvolume: persistentvolume.
phase: phase.
kube_persistentvolumeclaim_info
kube_persistentvolumeclaim_info/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Information about persistent volume claim. Sampled every 30 seconds.

persistentvolumeclaim: persistentvolumeclaim.
storageclass: storageclass.
volumename: volumename.
kube_persistentvolumeclaim_resource_requests_storage_bytes
kube_persistentvolumeclaim_resource_requests_storage_bytes/gauge
GAUGE, DOUBLE, By
prometheus_target
1.27.2-gke.1200 		The capacity of storage requested by the persistent volume claim. Sampled every 30 seconds.

persistentvolumeclaim: persistentvolumeclaim.
kube_persistentvolumeclaim_status_phase
kube_persistentvolumeclaim_status_phase/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The phase the persistent volume claim is currently in. Sampled every 30 seconds.

persistentvolumeclaim: persistentvolumeclaim.
phase: phase.

For more information, see PersistentVolume Metrics and PersistentVolumeClaim Metrics.

Pod metrics

A Pod is a group of one or more containers with a specification for how to run the containers, which share storage and network resources.

Table of Pod metrics

The Pod metrics let you monitor and alert on the behavior of your Pods. The following table shows the metrics available in the kube state metrics package:

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_pod_container_status_ready
kube_pod_container_status_ready/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Describes whether the containers readiness check succeeded. Sampled every 30 seconds.

container: container.
pod: pod.
uid: uid.
kube_pod_container_status_waiting_reason
kube_pod_status_container_status_waiting_reason/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Describes the reason the container is currently in waiting state. Sampled every 30 seconds.

container: container.
pod: pod.
reason: reason.
uid: uid.
kube_pod_status_phase
kube_pod_status_phase/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The pods current phase. Sampled every 30 seconds.

phase: phase.
pod: pod.
uid: uid.
kube_pod_status_unschedulable
kube_pod_status_unschedulable/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Describes the unschedulable status for the pod. Sampled every 30 seconds.

pod: pod.
uid: uid.

For more information, see Pod Metrics.

Sample queries for Pod metrics

To determine if you have unschedulable Pods, use the following PromQL expression:

sum(kube_pod_status_unschedulable{cluster="CLUSTER", namespace="NAMESPACE"})

To alert on a number of unschedulable pods in a namespace, you can use the following PromQL expression:

sum(kube_pod_status_unschedulable{cluster="CLUSTER", namespace="NAMESPACE"}) > LIMIT

You can use the kube_pod_container_status_waiting_reason metric to create an alert for a container stuck in a specific waiting state by using a PromQL expression like the following:

max_over_time(kube_pod_container_status_waiting_reason{reason="REASON", cluster="CLUSTER", namespace="NAMESPACE"}[5m]) >= 1

The value of REASON specifies the container's waiting state, for example:

  • CrashLoopBackOff
  • ImagePullBackOff
  • ContainerCreating

To create an alert for a container stuck in any of the waiting states, use the following PromQL expression:

max_over_time(kube_pod_container_status_waiting_reason{cluster="CLUSTER", namespace="NAMESPACE"}[5m]) >= 1

To determine how many containers are failing readiness checks, use the following PromQL expression

sum(kube_pod_container_status_ready) by (pod, container) == 0

Some of the query and alert expressions in this section were adapted from the kubernetes-apps.yaml file in the Prometheus community Kubernetes Helm Charts repository on GitHub.

Interactive playbooks

Kube state metrics are also used in the GKE interactive playbooks for troubleshooting unschedulable or crashlooping Pods. For more information about these failure modes, see the following troubleshooting documents:

Without the kube state metrics package enabled, the primary way to detect pod-scheduling issues is to query "Failed Scheduling" log events. After you enable the kube state metrics package, you can use the kube_pod_status_unschedulable metric, which serves the same purpose but is easier to aggregate and chart. By using the metric, you can see how many Pods are unschedulable and when the problem started.

Similarly, the GKE system metric kubernetes.io/container/restart_count can help you detect crashlooping Pods. The kube_pod_container_status_waiting_reason metric also enumerates crashlooping Pods, and it also lets you determine if Pods are stuck in waiting states other than CrashLookBackOff, like ImagePullBackOff and ContainerCreating.

To explore the interactive playbooks, do the following:

  1. In the Google Cloud console, go to the  Dashboards page:

    Go to Dashboards

    If you use the search bar to find this page, then select the result whose subheading is Monitoring.

  2. Filter the dashboard list by clicking the G​C​P category.
  3. Click the name of a "GKE Interactive Playbook" dashboard in the list.

Deployment metrics

A Deployment is a controller that updates the state of resources like Pods, to manage events like rollouts and turndowns.

Table of Deployment metrics

The Deployment metrics let you monitor and alert on the behavior of the controller. The following table shows the metrics available in the kube state metrics package:

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_deployment_spec_replicas
kube_deployment_spec_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Number of desired pods for a deployment. Sampled every 30 seconds.

deployment: deployment.
kube_deployment_status_replicas_available
kube_deployment_status_replicas_available/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of available replicas per deployment. Sampled every 30 seconds.

deployment: deployment.
kube_deployment_status_replicas_updated
kube_deployment_status_replicas_updated/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of updated replicas per deployment. Sampled every 30 seconds.

deployment: deployment.

For more information, see Deployment Metrics.

Sample queries for Deployment metrics

You can create charts and alerting policies for individual Deployments by filtering Deployment metrics by cluster, namespace, and the name of the Deployment.

For example, to compare the number of available replicas to the expected number of replicas in a single Deployment, you can use the following PromQL queries to plot both metrics on a single chart:

kube_deployment_spec_replicas{cluster="CLUSTER", namespace="NAMESPACE", deployment=DEPLOYMENT"}
and 
kube_deployment_status_replicas_available{cluster="CLUSTER", namespace="NAMESPACE", deployment=DEPLOYMENT"}

To alert on a failed or stalled Deployment, you can use the following PromQL expression:

(
  kube_deployment_spec_replicas{cluster="CLUSTER", namespace="NAMESPACE", deployment="DEPLOYMENT"}
    >
  kube_deployment_status_replicas_available{cluster="CLUSTER", namespace="NAMESPACE", deployment="DEPLOYMENT"}
) and (
  changes(kube_deployment_status_replicas_updated{cluster="CLUSTER", namespace="NAMESPACE", deployment="DEPLOYMENT"}[10m])
    ==
  0
)

Some of the query and alert expressions in this section were adapted from the kubernetes-apps.yaml file in the Prometheus community Kubernetes Helm Charts repository on GitHub.

StatefulSet metrics

A StatefulSet is a controller that manages the deployment and scaling of a set of Pods for stateful applications. This controller manages the the ordering and uniqueness of Pods.

Table of StatefulSet metrics

The StatefulSet metrics let you monitor and alert on the behavior of the controller. The following table shows the metrics available in the kube state metrics package:

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_statefulset_replicas
kube_statefulset_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Number of desired pods for a StatefulSet. Sampled every 30 seconds.

statefulset: statefulset.
kube_statefulset_status_replicas_ready
kube_statefulset_status_replicas_ready/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of ready replicas per StatefulSet. Sampled every 30 seconds.

statefulset: statefulset.
kube_statefulset_status_replicas_updated
kube_statefulset_status_replicas_updated/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of updated replicas per StatefulSet. Sampled every 30 seconds.

statefulset: statefulset.

For more information, see StatefulSet Metrics.

Sample queries for StatefulSet metrics

You can create charts and alerting policies for individual StatefulSets by filtering statefulset metrics by cluster, namespace, and the name of the StatefulSet.

For example, to compare the number of available replicas to the expected number of replicas in a single StatefulSet, you can use the following PromQL queries to plot both metrics on a single chart:

kube_statefulset_replicas{cluster="CLUSTER", namespace="NAMESPACE", statefulset="STATEFULSET"}
and 
kube_statefulset_status_replicas_ready{cluster="CLUSTER", namespace="NAMESPACE", statefulset="STATEFULSET"}

To alert on a failed or stalled StatefulSet rollout, you can use the following PromQL expression:

(
  kube_statefulset_replicas{cluster="CLUSTER", namespace="NAMESPACE", statefulset="STATEFULSET"}
    >
  kube_statefulset_status_replicas_ready{cluster="CLUSTER", namespace="NAMESPACE", statefulset="STATEFULSET"}
) and (
  changes(kube_statefulset_status_replicas_updated{cluster="CLUSTER", namespace="NAMESPACE", statefulset="STATEFULSET"}[10m])
    ==
  0
)

Some of the query and alert expressions in this section were adapted from the kubernetes-apps.yaml file in the Prometheus community Kubernetes Helm Charts repository on GitHub.

DaemonSet metrics

A DaemonSet is a controller that ensures that some set of Nodes runs a copy of a Pod. For example, as Nodes are added to a cluster, the DaemonSet adds Pods to the Nodes. This controller is useful for ensuring that certain processes run on every node.

Table of DaemonSet metrics

The DaemonSet metrics let you monitor and alert on the behavior of the controller. The following table shows the metrics available in the kube state metrics package:

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_daemonset_status_desired_number_scheduled
kube_daemonset_status_desired_number_scheduled/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of nodes that should be running the daemon pod. Sampled every 30 seconds.

daemonset: daemonset.
kube_daemonset_status_number_misscheduled
kube_daemonset_status_number_misscheduled/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of nodes running a daemon pod but are not supposed to. Sampled every 30 seconds.

daemonset: daemonset.
kube_daemonset_status_number_ready
kube_daemonset_status_number_ready/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of nodes that should be running the daemon pod and have one or more of the daemon pod running and ready. Sampled every 30 seconds.

daemonset: daemonset.
kube_daemonset_status_updated_number_scheduled
kube_daemonset_status_updated_number_scheduled/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The number of nodes that are running updated daemon pod. Sampled every 30 seconds.

daemonset: daemonset.

For more information, see DaemonSet Metrics.

Sample queries for DaemonSet metrics

You can create charts and alerting policies for individual DaemonSets by filtering daemonset metrics by cluster, namespace, and the name of the DaemonSet.

For example, to compare the number of available replicas to the expected number of replicas in a single DaemonSet, you can use the following PromQL queries to plot both metrics on a single chart:

kube_daemonset_status_updated_number_scheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonsetset=DAEMONSET"}
and 
kube_daemonset_status_desired_number_scheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonset=DAEMONSET"}

To alert on a failed or stalled DaemonSet rollout, you can use the following PromQL expression:

(
  (
    kube_daemonset_status_number_misscheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonset="DAEMONSET"}
      !=
    0
  ) or (
    kube_daemonset_status_updated_number_scheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonset="DAEMONSET"}
      !=
    kube_daemonset_status_desired_number_scheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonset="DAEMONSET"}
  )
) and (
  changes(kube_daemonset_status_updated_number_scheduled{cluster="CLUSTER", namespace="NAMESPACE", daemonset="DAEMONSET"}[5m])
    ==
  0
)

Some of the query and alert expressions in this section were adapted from the kubernetes-apps.yaml file in the Prometheus community Kubernetes Helm Charts repository on GitHub.

HorizontalPodAutoscaler metrics

A HorizontalPodAutoscaler (HPA) is a controller that periodically changes the number of pods in a workload, such as a Deployment or StatefulSet, in response to some metric like CPU or memory utilization. Changing the number of pods available to a workload keeps the workload responsive but efficient.

For more information about HPAs, see Viewing details about a Horizontal Pod Autoscaler.

Table of HPA metrics

The HorizontalPodAutoscaler metrics let you monitor and alert on the behavior of the controller. The following table shows the metrics available in the kube state metrics package:

The Cloud Monitoring metric names in this table must be prefixed with prometheus.googleapis.com/. That prefix has been omitted from the entries in the table.

PromQL metric name
Cloud Monitoring metric name
Kind, Type, Unit
Monitored resources
Required GKE version		 Description
Labels
kube_horizontalpodautoscaler_spec_max_replicas
kube_horizontalpodautoscaler_spec_max_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Upper limit for the number of pods that can be set by the autoscaler, cannot be smaller than MinReplicas. Sampled every 30 seconds.

horizontalpodautoscaler: horizontalpodautoscaler.
kube_horizontalpodautoscaler_spec_min_replicas
kube_horizontalpodautoscaler_spec_min_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Lower limit for the number of pods that can be set by the autoscaler, default 1. Sampled every 30 seconds.

horizontalpodautoscaler: horizontalpodautoscaler.
kube_horizontalpodautoscaler_spec_target_metric
kube_horizontalpodautoscaler_spec_target_metric/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The metric specifications used by this autoscaler when calculating the desired replica count. Sampled every 30 seconds.

horizontalpodautoscaler: horizontalpodautoscaler.
metric_name: metric_name.
metric_target_type: metric_target_type.
kube_horizontalpodautoscaler_status_condition
kube_horizontalpodautoscaler_status_condition/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		The condition of this autoscaler. Sampled every 30 seconds.

condition: condition.
horizontalpodautoscaler: horizontalpodautoscaler.
namespace: namespace.
status: status.
kube_horizontalpodautoscaler_status_current_replicas
kube_horizontalpodautoscaler_status_status_current_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Current number of replicas of pods managed by this autoscaler. Sampled every 30 seconds.

horizontalpodautoscaler: horizontalpodautoscaler.
kube_horizontalpodautoscaler_status_desired_replicas
kube_horizontalpodautoscaler_status_desired_replicas/gauge
GAUGE, DOUBLE, 1
prometheus_target
1.27.2-gke.1200 		Desired number of replicas of pods managed by this autoscaler. Sampled every 30 seconds.

horizontalpodautoscaler: horizontalpodautoscaler.

For more information, see Horizontal Pod Autoscaler Metrics.

Sample queries for HPA metrics

For example, to determine if the HPA is approaching the maximum number of replicas, you can plot the following ratio:

kube_horizontalpodautoscaler_status_current_replicas{cluster="CLUSTER", namespace="NAMESPACE", horizontalpodautoscaler="HPA"} /
kube_horizontalpodautoscaler_spec_max_replicas{cluster="CLUSTER", namespace="NAMESPACE", horizontalpodautoscaler="HPA"}

When the HPA is running with the maximum number of replicas, you might want to increase the spec for maximum number of pods. You can use the following PromQL expression to create an alert to notify you of this case:

kube_horizontalpodautoscaler_status_current_replicas{cluster="CLUSTER", namespace="NAMESPACE", horizontalpodautoscaler="HPA"}
  ==
kube_horizontalpodautoscaler_spec_max_replicas{cluster="CLUSTER", namespace="NAMESPACE", horizontalpodautoscaler="HPA"}

You can also compare the values of the kube_horizontalpodautoscaler_status_current_replicas and the kube_horizontalpodautoscaler_status_desired_replicas metrics to determine if there is a difference between the current and needed number of replicas. A difference might may indicate a resource constraint in the cluster. The following PromQL expression looks for differences between the current number of replicas and the needed, minimum, and maximum numbers of replicas, as well as changes in the current number of replicas:

(kube_horizontalpodautoscaler_status_desired_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"}
  !=
kube_horizontalpodautoscaler_status_current_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"})
  and
(kube_horizontalpodautoscaler_status_current_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"}
  >
kube_horizontalpodautoscaler_spec_min_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"})
  and
(kube_horizontalpodautoscaler_status_current_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"}
  <
kube_horizontalpodautoscaler_spec_max_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"})
  and
changes(kube_horizontalpodautoscaler_status_current_replicas{job="kube-state-metrics", namespace=~"NAMESPACE"}[15m]) == 0

The condition and status labels on the kube_horizontalpodautoscaler_status_condition metric can also help you detect when HPAs run into various failure modes. For example:

  • The condition ScalingLimited and status of true indicates that the HPA is bound by either its minimum or maximum replica count: 
    kube_horizontalpodautoscaler_status_condition{status="true", condition="ScalingLimited"} == 1

  • The condition AbleToScale and a status of false indicates that the HPA is encountering issues fetching or updating scales: 

    kube_horizontalpodautoscaler_status_condition{status="false", condition="AbleToScale"} == 1

  • The condition ScalingActive and a status of false indicates that the HPA is disabled or is unable to calculate a new scale: 

    kube_horizontalpodautoscaler_status_condition{status="false", condition="ScalingActive"} == 1

Some of the query and alert expressions in this section were adapted from the kubernetes-apps.yaml file in the Prometheus community Kubernetes Helm Charts repository on GitHub.