Autoscaling a cluster

This page shows you how to autoscale your Standard Google Kubernetes Engine (GKE) clusters. To learn about how the cluster autoscaler works, refer to Cluster autoscaler.

With Autopilot clusters, you don't need to worry about provisioning nodes or managing node pools because node pools are automatically provisioned through node auto-provisioning, and are automatically scaled to meet the requirements of your workloads.

Using cluster autoscaler

Note: Enabling or disabling cluster autoscaling might cause the control plane to restart, which takes several minutes to complete. Once autoscaling is enabled for at least one node pool, further changes to the cluster autoscaler configuration does not cause the control plane to restart until autoscaling is disabled for the last node pool. However, autoscaling might still take up to one minute for changes to propagate after the operation completes.

The following sections explain how to use cluster autoscaler.

Creating a cluster with autoscaling

gcloud

To create a cluster with autoscaling, use the --enable-autoscaling flag and specify --min-nodes and --max-nodes.

The following command creates a cluster with 30 nodes. Node autoscaling is enabled and resizes the number of nodes based on cluster load. The cluster autoscaler can reduce the size of the default node pool to 15 nodes or increase the node pool to a maximum of 50 nodes.

gcloud container clusters create cluster-name --num-nodes 30 \
    --enable-autoscaling --min-nodes 15 --max-nodes 50 [--zone compute-zone] | [--region compute-region]

In this command:

• --num-nodes specifies the number of nodes to create in each of the cluster's zones. The default is 3.
• --enable-autoscaling indicates that autoscaling is enabled.
• --min-nodes specifies the minimum number of nodes for the default node pool.
• --max-nodes specifies the maximum number of nodes for the default node pool.
• --zone specifies the compute zone in which the autoscaler should create new nodes.
• --region specifies the [compute region] in which the autoscaler should create new nodes.

Console

To create a new cluster in which the default node pool has autoscaling enabled:

1. Visit the Google Kubernetes Engine menu in Cloud Console.

   Visit the Google Kubernetes Engine menu

2. Click Create.

3. Configure your cluster as desired.

4. From the navigation pane, under Node Pools, click default-pool.

5. Select the Enable autoscaling checkbox.

6. Change the values of the Minimum number of nodes and Maximum number of nodes fields as desired.

7. Click Create.

Adding a node pool with autoscaling

gcloud

The following command creates a node pool of size 3 (default), with node autoscaling based on cluster load that scales the node pool to a maximum of 5 nodes and a minimum of 1 node:

gcloud container node-pools create pool-name --cluster cluster-name \
    --enable-autoscaling --min-nodes 1 --max-nodes 5 [--zone compute-zone]

In this command:

• --cluster indicates the cluster in which the node is created.
• --enable-autoscaling indicates that autoscaling is enabled.
• --min-nodes specifies the minimum number of nodes for the node pool.
• --max-nodes specifies the maximum number of nodes for the node pool.
• --zone specifies the compute zone in which the autoscaler should create new nodes.

Console

To add a node pool with autoscaling to an existing cluster:

1. Visit the Google Kubernetes Engine menu in Cloud Console.

   Visit the Google Kubernetes Engine menu

2. In the cluster list, click the name of the cluster you want to modify.

3. Click Add Node Pool.

4. Configure the node pool as desired.

5. Under Size, select the Enable autoscaling checkbox.

6. Change the values of the Minimum number of nodes and Maximum number of nodes fields as desired.

7. Click Create.

Enabling autoscaling for an existing node pool

gcloud

To enable autoscaling for an existing node pool, run the following command:

gcloud container clusters update cluster-name --enable-autoscaling \
    --min-nodes 1 --max-nodes 10 --region compute-region || --zone compute-zone --node-pool default-pool

In this command:

• --enable-autoscaling indicates that autoscaling is enabled.
• --min-nodes specifies the minimum number of nodes for the node pool.
• --max-nodes specifies the maximum number of nodes for the node pool.
• --region specifies the cluster's compute region.
• --node-pool specifies the desired node pool. If you have only one node pool, supply default-pool to this flag.

Console

To enable autoscaling for an existing node pool:

1. Visit the Google Kubernetes Engine menu in Cloud Console.

   Visit the Google Kubernetes Engine menu

2. In the cluster list, click the name of the cluster you want to modify.

3. Click the Nodes tab.

4. Under Node Pools, click the name of the node pool you want to modify, then click Edit.

5. Under Size, select the Enable autoscaling checkbox.

6. Change the values of the Minimum number of nodes and Maximum number of nodes fields as desired.

7. Click Save.

Disabling autoscaling for an existing node pool

gcloud

To disable autoscaling for a specific node pool, run the following command:

gcloud container clusters update cluster-name --no-enable-autoscaling \
    --node-pool pool-name [--zone compute-zone --project project-id]

In this command, --no-enable-autoscaling instructs the cluster to disable autoscaling.

The cluster size is fixed at the cluster's current default node pool size, which can be manually updated.

Console

To disable autoscaling for a specific node pool:

1. Visit the Google Kubernetes Engine menu in Cloud Console.

   Visit the Google Kubernetes Engine menu

2. In the cluster list, click the name of the cluster you want to modify.

3. Click the Nodes tab.

4. Under Node Pools, click the name of the node pool you want to modify, then click Edit.

5. Under Size, clear the Enable autoscaling checkbox.

6. Click Save.

Troubleshooting

See the following troubleshooting information for cluster autoscaler:

• You might be experiencing one of the limitations for cluster autoscaler.
• If you are having problems with downscaling your cluster, see Pod scheduling and disruption. You might have to add a PodDisruptionBudget for the kube-system Pods. For more information about manually adding a PodDisruptionBudget for the kube-system Pods, see the Kubernetes cluster autoscaler FAQ.
• When scaling down, cluster autoscaler respects scheduling and eviction rules set on Pods. These restrictions can prevent a node from being deleted by the autoscaler. A node's deletion could be prevented if it contains a Pod with any of these conditions:
  • The Pod's affinity or anti-affinity rules prevent rescheduling.
  • The Pod has local storage.
  • The Pod is not managed by a Controller such as a Deployment, StatefulSet, Job or ReplicaSet.

For more information about cluster autoscaler and preventing disruptions, see the following questions in the Kubernetes cluster autoscaler FAQ:

• How does scale-down work?
• Does Cluster autoscaler work with PodDisruptionBudget in scale-down?
• What types of Pods can prevent Cluster autoscaler from removing a node?

What's next

• Learn more about cluster autoscaler.
• View cluster autoscaler events.