Managing cluster node pool

Available in VPC

You can check the node pool list within a cluster and perform management tasks such as viewing individual node pool's details, deleting, upgrading, changing the number of worker nodes, etc.

Check the list of node pools

List of all node pools

To check the list of the node pools created within a service, click Services > Containers > Ncloud Kubernetes Service > Node pools in the VPC environment of NAVER Cloud Platform console.

List of node pools within individual clusters

The following describes how to view the list of node pools in each cluster.

1. From the VPC environment of NAVER Cloud Platform console, click the Services > Containers > Ncloud Kubernetes Service menus, in order.
2. Click the row of the cluster whose node pool list you want to see from the list of clusters.

View node pool details

To view the details for each node pool, click the name of the node pool you want to see from the node pool list.

Add a node pool

The following describes how to add a new node pool to a cluster.

1. Click the individual cluster row from the cluster list.
2. Click the [Add] button under the node pool area in the Cluster details tab.
3. Enter the node pool name, server image name, server type, number of nodes, Kubernetes Label, Taint, subnet, and Node IAM Role and then click the [Next] button.
4. After finally checking the node pool settings, click the [Create] button.

Change the number of worker nodes in node pool</a

Change the number of worker nodes manually

You can manually change the number of worker nodes in a cluster node pool, or set it to be automatically scaled using Cluster Autoscaler.
The following describes how to manually change the number of worker nodes in a cluster node pool.

1. Click the individual cluster row from the cluster list.
2. Click the name of the node pool you want to view from the node pool list under the Cluster details tab.
3. In the node pool details page, click the [Edit] button.
4. In the Settings pop-up window, click the Not set button, and then enter the number of worker nodes.
5. Click the [Edit] button.

Auto scaling of the number via Cluster Autoscaler

In order to automatically scale the number of worker nodes using Cluster Autoscaler, see Use Cluster Autoscaler.

Edit Kubernetes Label and Taint of the node pool

The following describes how to edit the Kubernetes Label and Taint of the node pool.

1. Click the individual cluster row from the cluster list.
2. Click the name of the node pool you want to view from the node pool list under the Cluster details tab.
3. In the node pool details page, click the [Edit] button below the Kubernetes Label or Taint list.
4. After changing the Kubernetes Label or Taint, click the [OK] button.

Delete node pool

The following shows how to delete a cluster node pool.

1. Click the individual cluster row from the cluster list.
2. Click the name of the node pool you want to delete from the node pool list under the Cluster details tab.
3. In the node pool details page, click the [Delete] button.
4. Enter the node pool name in the confirmation pop-up window, and then click the [Delete] button.

Identify node pools through node labels

Information about the node pool to which each node belongs is added to the node label, which is displayed in the form of "ncloud.com/nks-nodepool: {node pool name}." The "--show-labels" option can be used to view the node label. You can use node labels to identify the node pool, and effectively deploy pods according to each node pool's specifications.
Enter the command shown below to check the node label.

$ kubectl --kubeconfig $KUBE_CONFIG get nodes --show-labels

Upgrade node pool

You can specify the number of max-surge-upgrade nodes and max-unavailable-upgrade nodes and perform the node pool's version upgrade. Node pool version upgrade is performed as follows:

1. Create as many new version nodes as the number of max-surge-upgrade nodes, and wait until the nodes are registered.
2. Adjust the settings so that no more pods can be scheduled to the node to be replaced, and then relocate the existing pods to other nodes.
3. Remove the node to be replaced.
4. Repeat the above until all the nodes are replaced with the newer version.

Pre-upgrade check

See the following and check for elements that may affect the service before upgrading the node pool.

• Changes in new version: See Kubernetes changelog and check if the changes in the new version may affect your service.
• Version discrepancy policy: See Version Skew Policy and check the version compatibility among clusters and their components.
• Admission webhook: If there are webhooks present in the cluster, an upgrade may end up in an impasse. See Dynamic Admission Control and take necessary measures in advance before upgrading.
• Secure available servers: Secure as many available servers as the number of the max-surge-upgrade nodes for stability of the upgrade.
• Check changes to node information: upgrading the node pool will reset or change the existing node-related information. Check the information such as local volume information, node name, IP, label, etc., in advance before upgrading.

You can set details related to the upgrade by referencing the following.

• PodDisruptionBudget: you can maintain the pods in service at a ratio or number you want, even during the cluster upgrade. See Specifying a Disruption Budget.
• Readiness probe: you can adjust the settings so that only the pods in a serviceable state are accessible through the Ncloud Kubernetes Service resource when pods are redeployed during the node pool replacement. See Define readiness probes.

How to upgrade

The following describes how to upgrade a node pool.

1. Click the row of the cluster with the node pool to upgrade from the list of clusters.
2. Click the [Upgrade] button under the name of the node pool to upgrade in the cluster details tab.
3. Set the number of max-surge-upgrade nodes and max-unavailable-upgrade nodes, and then perform the upgrade.
   • Number of max-surge-upgrade nodes: this refers to the number of nodes that can be added during the upgrade. The default value is 1, and you can specify a minimum of 0 to a maximum of 0.
   • Number of max-unavailable-upgrade nodes: this refers to the number of nodes that can safely become unserviceable during the upgrade. The default value is 0, and you can specify a maximum of 5.
     When the number of existing nodes decreases, the amount of reduction is as many as this number. When new nodes are added, the amount of increase can be as many as the sum of the maximum max-surge-upgrade nodes and max-unavailable-upgrade nodes.

Examples of setting the number of nodes

• <example 1> Node pool size 5, number of additional increase nodes 1, number of unserviceable nodes 0
  As one more node can be created than the size of the node pool, a maximum of 6 nodes may exist.
  Nodes cannot decrease to fewer than the existing node pool size.
  A relatively slow but stable upgrade is available, since the nodes are replaced one by one.
• <example 2> Node pool size 5, number of additional increased nodes 5, number of unserviceable nodes 0
  As 5 more can be created than the node pool size, there can be up to 10 nodes.
  Nodes cannot decrease to fewer than the existing node pool size.
  A relatively fast and stable upgrade is available since it adds many nodes at once.
• <example 3> Node pool size 5, number of additional increase nodes 0, number of unserviceable nodes 5
  The number may be smaller than the existing node pool size, and at least 0 nodes may exist.
  The number of nodes can't be more than the existing node pool size.
  This method is fast, but the cluster may become unstable since many nodes can be replaced at once.