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    Container Service for Kubernetes:Modify a node pool

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    Container Service for Kubernetes:Modify a node pool

    Last Updated:Apr 22, 2024

    Container Service for Kubernetes (ACK) allows you to modify the configuration of a node pool in the ACK console. For example, you can change the billing method, vSwitches, instance types, and system disks that are used by a node pool. You can also enable or disable auto scaling for a node pool. This topic describes how to modify the configuration of a node pool.

    Table of contents

    Prerequisites

    Precautions

    • In most cases, after you modify a node pool, the modified configuration applies only to newly added nodes. Only in certain cases such as changing the labels and taints of existing nodes, the modified configuration also applies to the existing nodes in the node pool. Node pool O&M operations, such as node pool upgrades, node repairing, vulnerability patching, and kubelet configuration customization, will modify the configuration of the existing nodes in the node pool.

    • Modifications to a node pool do not affect existing nodes or existing applications in the node pool.

    Procedure

    1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

    2. On the Clusters page, click the name of the cluster that you want to manage and choose Nodes > Node Pools in the left-side navigation pane.

    3. On the Node Pools page, find the node pool that you want to modify and click Edit in the Actions column.

    4. In the Create Node Pool dialog box, set the node pool parameters.

      Parameter

      Modifiable

      Description

      Region

      错

      The region where the cluster resides.

      Container Runtime:

      错

      For more information about container runtimes, see Comparison of Docker, containerd, and Sandboxed-Container .

      VPC

      错

      The virtual private cloud (VPC) where the cluster resides is automatically selected.

      vSwitch

      对

      You can select up to three vSwitches that are deployed in different zones. If no vSwitch is available, click Create vSwitch. For more information, see Create and manage vSwitches.

      When the node pool is scaled out, nodes in the zones where the selected vSwitches reside are added to the node pool. Node pools are scaled based on the scaling policy that you select in the advanced settings of the node pool.

      Auto Scaling

      对

      Specify whether to enable auto scaling. You can use the auto scaling feature of ACK to dynamically scale computing resources for your business based on business requirements and scaling policies in a cost-effective manner. For more information about the auto scaling feature of ACK, see Auto scaling overview.

      Before you enable auto scaling, you must configure auto scaling settings. For more information, see Configure auto scaling.

      Billing Method

      对

      The following billing methods are supported for nodes in a node pool: pay-as-you-go, subscription, and preemptible instances. To ensure that all nodes in a node pool use the same billing method, ACK does not allow you to change the billing method of a node pool among pay-as-you-go, subscription, and preemptible instances. For example, you cannot change the billing method of a node pool from pay-as-you-go or subscription to preemptible instances.

      • If you select the pay-as-you-go billing method, Elastic Compute Service (ECS) instances in the node pool are billed on a pay-as-you-go basis. You are not charged for using the node pool.

      • If you select the subscription billing method, you must set the Duration and Auto Renewal parameters.

      • If you select the preemptible instances billing method, you must set the following parameter at the same time.

        Upper Price Limit of Current Instance Spec: If the real-time market price of an instance type that you select is lower than the value of this parameter, a preemptible instance of this instance type is created. After the protection period (1 hour) ends, the system checks the spot price and resource availability of the instance type every 5 minutes. If the real-time market price exceeds your bid price or if the resource inventory is insufficient, the preemptible instance is released.

      Note

      Instance Type

      对

      You can select multiple instance types. You can filter instance types by vCPU, memory, architecture, or category.

      Note

      The instance types that you select are displayed in the Selected Types section.

      When the node pool is scaled out, ECS instances of the instance types that you select for the Instance Type parameter are created. The scaling policy of the node pool determines which instance types are used to create new nodes during scale-out activities. Select multiple instance types to improve the success rate of node pool scale-out operations.

      If the node pool fails to be scaled out because the instance types are unavailable or the instances are out of stock, you can specify more instance types for the node pool. The ACK console automatically evaluates the scalability of the node pool. You can view the scalability level when you create the node pool or after you create the node pool.

      Note

      • Modifications to the instance types used by a node pool apply only to newly added nodes and do not take effect on existing nodes in the node pool. If you want to change the instance type of the existing nodes in a node pool, perform the following steps:

        • If you want to upgrade the ECS instances, go to the ECS console and perform the operation. For more information, see Change resource configurations.

        • To change the instance type of existing nodes, you must first remove the nodes from the cluster. Change the instance type for the node pool and then re-add the nodes to the node pool. For more information about how to remove a node from a cluster, see Remove a node.

      • ARM-based ECS instances support only images for ARM. For more information about ARM-based node pools, see Configure an ARM-based node pool.

      Selected Types

      对

      The selected instance types are displayed.

      System Disk

      对

      Enhanced SSDs (ESSDs), standard SSDs, and ultra disks are supported. The types of system disks that you can select depend on the instance types that you select. For more information about the disk types supported by different instance types, see Instance families. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select.

      Note

      • Modifications to the system disks used by a node pool apply only to newly added nodes and do not take effect on the existing nodes in the node pool.

      • You can specify a custom performance level for an ESSD. You can select higher performance levels for ESSDs with larger storage capacities. For example, you can select performance level 2 for an ESSD with a storage capacity of more than 460 GiB. You can select performance level 3 for an ESSD with a storage capacity of more than 1,260 GiB. For more information, see Capacities and performance levels.

      • The Encrypt Disk option is available only for ESSDs. System disks support only the aes-256 encryption algorithm. For more information about system disk encryption, see Encrypt system disks.

      Mount Data Disk

      对

      ESSDs, standard SSDs, and ultra disks are supported. The disk types that you can select depend on the instance types that you select. For more information about the disk types supported by different instance types, see Instance families. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select.

      Note

      • Modifications to the data disks used by a node pool apply only to newly added nodes and do not take effect on the existing nodes in the node pool.

      • You can specify a custom performance level for an ESSD. You can select higher performance levels for ESSDs with larger storage capacities. For example, you can select performance level 2 for an ESSD with a storage capacity of more than 460 GiB. You can select performance level 3 for an ESSD with a storage capacity of more than 1,260 GiB. For more information, see Capacities and performance levels.

      • The Encrypt Disk option is available only for ESSDs. Data disk encryption supports only the aes-256 algorithm. You can use only the default service Customer Managed Key (CMK) to encrypt data disks in the China (Nanjing - Local Region), China (Fuzhou - Local Region), Thailand (Bangkok), and South Korea (Seoul) regions. Bring Your Own Key (BYOK) is not supported. For more information about data disk encryption, see Encrypt data disks.

      • The maximum number of data disks that can be mounted depends on the instance types that you select. You can view the selected data disks and the remaining number of data disks that you can mount on the right side of Mount Data Disk.

      Operating System

      对

      ACK supports images for the following operating systems:

      • Alibaba Cloud Linux 3

      • Alibaba Cloud Linux 3 for ARM.

      • ContainerOS

      • Alibaba Cloud Linux 2

      • Alibaba Cloud Linux UEFI 2

      • Windows

      • Windows Core

      • CentOS

      For more information, see Overview of OS images.

      Note

      • After you change the OS image of the node pool, the change takes effect only on newly added node. The existing nodes in the node pool still use the original OS image. For more information about how to update the OS images of existing nodes, see Node pool updates.

      • To ensure that all nodes in the node pool use the same OS image, ACK allows you to only update the node OS image to the latest version. ACK does not allow you to change the type of OS image.

      Logon Type

      对

      Valid values: Key Pair, Password, and Later.

      Note

      If you select Reinforcement based on classified protection for the Security Reinforcement parameter, only the Password option is supported.

      • Configure the logon type when you create the node pool:

        • Key Pair: Alibaba Cloud SSH key pairs provide a secure and convenient method to log on to ECS instances. An SSH key pair consists of a public key and a private key. SSH key pairs support only Linux instances. For more information, see Overview.

        • Password: The password must be 8 to 30 characters in length, and must contain uppercase letters, lowercase letters, digits, and special characters.

      • Configure the logon type after you create the node pool: For more information, see Bind an SSH key pair to an instance and Reset the logon password of an instance.

      Public IP

      对

      Specify whether to allocate an IPv4 address to each node. If you clear the check box, no public IP address is allocated. If you select the check box, you must also set the Bandwidth Billing Method and Peak Bandwidth parameters.

      Note

      This parameter takes effect only on newly added nodes and does not take effect on existing nodes. If you want to enable an existing node to access the Internet, you must create an elastic IP address (EIP) and associate the EIP with the node. For more information, see Associate an EIP with an ECS instance.

      CloudMonitor Agent

      对

      Specify whether to install the CloudMonitor agent. After you install the CloudMonitor agent on ECS nodes, you can view the monitoring information about the nodes in the CloudMonitor console.

      Note

      This parameter takes effect only on newly added nodes and does not take effect on existing nodes. If you want to install the CloudMonitor agent on an existing ECS node, go to the CloudMonitor console.

    5. Click Show Advanced Options to configure advanced settings.

      Show advanced settings

      Parameter

      Modifiable

      Description

      ECS Tags

      对

      Add tags to the ECS instances that are automatically added during auto scaling. Tag keys must be unique. A key cannot exceed 128 characters in length. Keys and values cannot start with aliyun or acs:. Keys and values cannot contain https:// or http://.

      An ECS instance can have at most 20 tags. To increase the quota limit, submit an application in the Quota Center console. The following tags are automatically added to an ECS node by ACK and Auto Scaling. Therefore, you can add 17 tags to an ECS node.

      • The following two ECS tags are added by ACK:

        • ack.aliyun.com:<Cluster ID>

        • ack.alibabacloud.com/nodepool-id:<Node pool ID>

      • The following ECS tag is added by Auto Scaling: acs:autoscaling:scalingGroupId:<Scaling group ID>.

      Note

      • After you enable auto scaling, the following ECS tags are added to the node pool by default: k8s.io/cluster-autoscaler:true and k8s.aliyun.com:true.

      • The auto scaling component simulates scale-out activities based on node labels and taints. For this purpose, the format of node labels is changed to k8s.io/cluster-autoscaler/node-template/label/Label key:Label value and the format of taints is changed to k8s.io/cluster-autoscaler/node-template/taint/Taint key/Taint value:Taint effect.

      • Modifications to the ECS tags apply only to newly added nodes and do not take effect on existing nodes in the node pool. If you want to modify the tags of existing nodes in the node pool, go to the ECS console and modify the tags of the ECS instances.

      Taints

      对

      Add taints to nodes. A taint consists of a key, a value, and an effect. A taint key can be prefixed. If you want to specify a prefixed taint key, add a forward slash (/) between the prefix and the remaining content of the key. For more information, see Taints and tolerations. The following limits apply to taints:

      • Key: A key must be 1 to 63 characters in length, and can contain letters, digits, hyphens (-), underscores (_), and periods (.). A key must start and end with a letter or digit.

        If you want to specify a prefixed key, the prefix must be a subdomain name. A subdomain name consists of DNS labels that are separated by periods (.), and cannot exceed 253 characters in length. It must end with a forward slash (/). For more information about subdomain names, see DNS subdomain names.

      • Value: A value cannot exceed 63 characters in length, and can contain letters, digits, hyphens (-), underscores (_), and periods (.). A value must start and end with a letter or digit. You can also leave a value empty.

      • You can specify the following effects for a taint: NoSchedule, NoExecute, and PreferNoSchedule.

        • NoSchedule: If a node has a taint whose effect is NoSchedule, the system does not schedule pods to the node.

        • NoExecute: Pods that do not tolerate this taint are evicted after this taint is added to a node. Pods that tolerate this taint are not evicted after this taint is added to a node.

        • PreferNoSchedule: The system attempts to avoid scheduling pods to nodes with taints that are not tolerated by the pods.

      Note

      Modifications to the taints apply only to newly added nodes and do not take effect on existing nodes in the node pool. If you want to modify the taints of existing nodes in the node pool, select Add Labels and Taints to Existing Nodes in the Node Label parameter. You can also click Manage Labels and Taints in the upper-right corner of the Nodes page to manually modify the taints.

      Node Label

      对

      Add labels to nodes. A label is a key-value pair. A label key can be prefixed. If you want to specify a prefixed label key, add a forward slash (/) between the prefix and the remaining content of the key. The following limits apply to labels:

      • The key of a label must be 1 to 63 characters in length, and can contain letters, digits, hyphens (-), underscores (_), and periods (.). It must start and end with a letter or a digit.

        If you want to specify a prefixed key, the prefix must be a subdomain name. A subdomain name consists of DNS labels that are separated by periods (.), and cannot exceed 253 characters in length. It must end with a forward slash (/). For more information about subdomain names, see Subdomain names.

        The following prefixes are used by key Kubernetes components and cannot be used in node labels:

        • kubernetes.io/

        • k8s.io/

        • Prefixes that end with kubernetes.io/ or k8s.io/. Example: test.kubernetes.io/.

          However, you can still use the following prefixes:

          • kubelet.kubernetes.io/

          • node.kubernetes.io

          • Prefixes that end with kubelet.kubernetes.io/.

          • Prefixes that end with node.kubernetes.io.

      • The value of a label cannot exceed 63 characters in length, and can contain letters, digits, hyphens (-), underscores (_), and periods (.). The value of a label can be empty or start and end with a letter or a digit.

      • If you select Set New Nodes to Unschedulable, nodes are unschedulable when they are added to the cluster. You can set an existing node to schedulable on the Nodes page in the ACK console.

      Show details about the Add Labels and Taints to Existing Nodes parameter

      If you select this checkbox, modifications to labels and taints apply to both existing nodes and newly added nodes.

      When this checkbox is selected, the system synchronized the label or taint change of the node pool to the existing nodes in an incremental way instead of overwriting the labels of taints of the existing nodes. Assume that Node A has the following labels:

      • testA : testA

      • testB : testB

      The node pool uses the following label setting: testA : testA. After you change the label setting of the node pool to testC : testC,

      testA : testA is removed from the nodes in the node pool and testC : testC is added to the nodes. Consequently, Node A has the following labels after you submit the change:

      • testB : testB

      • testC : testC

      Show details about the Set to Unschedulable parameter

      If you select this checkbox, newly added nodes are unschedulable when they are added to the cluster. You can set an existing node to schedulable on the Nodes page in the ACK console.

      Note

      This parameter applies only to newly added nodes and do not take effect on existing nodes in the node pool.

      Scaling Policy

      错

      • Priority: The system scales the node pool based on the priorities of the vSwitches that you select for the node pool. The vSwitches that you select are displayed in descending order of priority. If Auto Scaling fails to create ECS instances in the zone of the vSwitch with the highest priority, Auto Scaling attempts to create ECS instances in the zone of the vSwitch with a lower priority.

      • Cost Optimization: The system creates instances based on the vCPU unit prices in ascending order. Preemptible instances are preferentially created when multiple preemptible instance types are specified in the scaling configurations. If preemptible instances cannot be created due to reasons such as insufficient stocks, the system attempts to create pay-as-you-go instances.

        If you select Preemptible Instance for the Billing Method parameter, you must set the following parameters:

        • Percentage of Pay-as-you-go Instances: Specify the percentage of pay-as-you-go instances in the node pool. Valid values: 0 to 100.

        • Enable Supplemental Preemptible Instances: After you enable this feature, Auto Scaling automatically creates the same number of preemptible instances 5 minutes before the system reclaims the existing preemptible instances. The system sends a notification to Auto Scaling 5 minutes before it reclaims preemptible instances.

        • Enable Supplemental Pay-as-you-go Instances: After you enable this feature, Auto Scaling attempts to create pay-as-you-go ECS instances to meet the scaling requirement if Auto Scaling fails to create preemptible instances for reasons such as that the unit price is too high or preemptible instances are out of stock.

      • Distribution Balancing: The even distribution policy takes effect only when you select multiple vSwitches. This policy ensures that ECS instances are evenly distributed among the zones (the vSwitches) of the scaling group. If ECS instances are unevenly distributed across the zones due to reasons such as insufficient stocks, you can perform a rebalancing operation.

      Custom Image

      对

      After you specify Custom Image, the custom image will replace the default system image.

      • Custom Images: All nodes in the cluster are deployed based on the custom image. For more information about how to create a custom image, see Create a Kubernetes cluster by using a custom image.

      • Shared Images: All nodes in the cluster are deployed based on the shared image. For more information about shared images, see Procedure.

      Note

      • You can use only custom images created based on Alibaba Cloud Linux, RHEL 8.x, and CentOS 7.x.

      • To use this feature, submit an application in the Quota Center console.

      RDS Whitelist

      对

      Click Select RDS Instance to add node IP addresses to the whitelist of an ApsaraDB RDS instance.

      User Data

      对

      Nodes automatically run user-data scripts after they are added to the cluster. For more information about user-data scripts, see User-data scripts.

      For example, if you enter echo "hello world", a node runs the following script: 

      #!/bin/bash
[Node initialization script]
echo "hello world"
      Note

      After you create a cluster or add nodes, the execution of the user-data script on a node may fail. We recommend that you log on to a node and run the grep cloud-init/var/log/messages command to view the execution log and check whether the execution succeeds or fails on the node.

    6. Click Confirm. On the Node Pools page, check the status of the node pool. If Updating is displayed in the Status column, the scale-out activity is in progress. After the scale-out activity is completed, Active is displayed in the Status column.

    References