Modify a node pool in an ACK cluster - Container Service for Kubernetes

After a node pool is created in the cluster, Container Service for Kubernetes (ACK) allows you to modify its configuration 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 configurations of a node pool.

Precautions

After you modify a node pool, the modifications generally apply to new nodes, and to existing nodes only in specific cases such as changing their labels and taints. If you perform O&M operations on a node pool, such as node pool upgrades, node repairing, Common Vulnerabilities and Exposures (CVE) patching, and kubelet configuration customization, the configurations of the existing nodes in the node pool are also modified.
Modifications to a node pool do not affect existing nodes or applications in the node pool.

Procedure

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side navigation pane, choose Nodes > Node Pools.
On the Node Pools page, find the node pool that you want to modify and click Edit in the Actions column.

In the dialog box that appears, modify the parameters of the node pool.

Note

In the following table, indicates that the parameter cannot be modified, and indicates that the parameter can be modified.

Parameter	Modifiable	Description
Region		The region where the cluster resides.
Container Runtime		For more information about container runtimes, see Comparison of Docker, containerd, and Sandboxed-Container.
Auto Scaling		Specify whether to enable auto scaling. This feature provides cost-effective computing resource scaling based on resource demand and scaling policies. For more information, see Auto scaling overview. Before you enable this feature, you need to enable node auto scaling for the node pool. For more information, see Step 1: Enable node auto scaling.
VPC		The virtual private cloud (VPC) in which the cluster resides is automatically selected.
vSwitch		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 in which 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 Options section of the node pool.
Billing Method		The following billing methods are supported for nodes in a node pool: Pay-As-You-Go, Subscription, and Preemptible Instance. To ensure that all nodes in a node pool use the same billing method, ACK does not allow you to switch the billing method of a node pool between Pay-As-You-Go or Subscription and Preemptible Instance. For example, you cannot change the billing method of a node pool from Preemptible Instance to Pay-As-You-Go or Subscription. If you select the Pay-As-You-Go billing method, you are charged for the Elastic Compute Service (ECS) instances in the node pool 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 configure the Duration and Auto Renewal parameters. If you select the Preemptible Instance billing method, you must configure 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) elapses, 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. ACK supports only preemptible instances with a protection period. For more information, see What are preemptible instances and Best practices for preemptible instance-based node pools. Note If you change the billing method of a node pool, the change takes effect only on newly added nodes. The existing nodes in the node pool still use the original billing method. For more information about how to change the billing method of existing nodes in a node pool, see Change the billing method of an instance from pay-as-you-go to subscription. ACK supports only preemptible instances with a protection period. For more information, see Best practices for preemptible instance-based node pools.
Instance Type		Select the ECS instances used by the worker node pool based on instance types or attributes. You can filter ECS instances by attributes such as vCPU, memory, instance family, and architecture. When the node pool is scaled out, ECS instances of the selected instance types 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. For more information about ECS instance types, see Overview of instance families. For more information about node pool scalability, see Check the scalability of a node pool. Note ARM-based ECS instances support only ARM images. For more information about ARM-based node pools, see Configure an ARM-based node pool. If you select only GPU-accelerated instances, you can select Enable GPU Sharing on demand. For more information, see cGPU overview.
Operating System		Container Service for Kubernetes supports ContainerOS, Alibaba Cloud Linux 3, Ubuntu, and Windows. 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.
System Disk		ESSD AutoPL, Enterprise SSD (ESSD), ESSD Entry, Standard SSD, and Ultra Disk are supported. The types of system disks that you can select depend on the instance types that you select. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select. For more information about disks, see Overview of Block Storage. For more information about disk types supported by different instance types, see Overview of instance families. Note If you select Enterprise SSD (ESSD) as the system disk type, you can set a custom performance level for the system disk. You can select higher PLs for ESSDs with larger storage capacities. For example, you can select PL 2 for an ESSD with a storage capacity of more than 460 GiB. You can select PL 3 for an ESSD with a storage capacity of more than 1,260 GiB. For more information, see Capacities and performance levels. You can select Encryption only if you set the system disk type to Enterprise SSD (ESSD). By default, the default service CMK is used to encrypt the system disk. You can also use an existing CMK generated by using BYOK in KMS. You can select More System Disk Types and select a disk type other than the current one in the System Disk section to improve the success rate of system disk creation. The system will attempt to create a system disk based on the specified disk types in sequence.
Mount Data Disk		ESSD AutoPL, Enterprise SSD (ESSD), ESSD Entry, SSD, and Ultra Disk are supported. The disk types that you can select depend on the instance types that you select. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select. For more information about disks, see Overview of Block Storage. For more information about disk types supported by different instance types, see Overview of instance families. ESSD AutoPL disks provide the following features: Performance provision: The performance provision feature allows you to configure provisioned performance settings for ESSD AutoPL disks to meet storage requirements that exceed the baseline performance without the need to extend the disks. Performance burst: The performance burst feature allows ESSD AutoPL disks to burst their performance when spikes in read/write workloads occur and reduce the performance to the baseline level at the end of workload spikes. ESSDs provide the following features: Custom Performance. You can select higher PLs for ESSDs with larger storage capacities. For example, you can select PL 2 for an ESSD with a storage capacity of more than 460 GiB. You can select PL 3 for an ESSD with a storage capacity of more than 1,260 GiB. For more information, see Capacity and PLs. You can select Encryption for all disk types when you specify the type of data disk. By default, the default service CMK is used to encrypt the data disk. You can also use an existing CMK generated by using BYOK in KMS. You can also use snapshots to create data disks in scenarios where container image acceleration and fast loading of large language models (LLMs) are required. This improves the system response speed and enhances the processing capability. Make sure that a data disk is mounted to `/var/lib/container` on each node, and `/var/lib/kubelet` and `/var/lib/containerd` are mounted to the `/var/lib/container`. For other data disks on the node, you can perform the initialization operation and customize their mount directories. For more information, see Can I mount a data disk to a custom directory in an ACK node pool? Note You can attach up to 64 data disks to an ECS instance. The maximum number of disks that can be attached to an ECS instance varies based on the instance type. To query the maximum number of disks that you can attach to an ECS instance of a specific instance type, call the DescribeInstanceTypes operation and check the DiskQuantity parameter in the response.
Auto Scaling		Specify whether to enable auto scaling. This feature provides cost-effective computing resource scaling based on resource demand and scaling policies. For more information, see Auto scaling overview. Before you enable this feature, you need to enable node auto scaling for the node pool. For more information, see Step 1: Enable node auto scaling.

Click the first Advanced Options (Optional) to configure Scaling Policy.

Parameter	Modifiable	Description
Scaling Policy		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. When Billing Method is set to Preemptible Instance, you can configure the following parameters in addition to the Enable Supplemental Preemptible Instances parameter: 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 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. Important You cannot change the scaling policy of a node pool after the node pool is created. When Billing Method is set to Preemptible Instance, you can specify whether to turn on Enable Supplemental Preemptible Instances. After this feature is enabled, when a system message that indicates preemptible instances are reclaimed is received, the node pool with auto scaling enabled attempts to create new instance to replace the reclaimed the preemptible instances.

Click the second Advanced Options (Optional) to configure other advanced settings, such as the resource group, ECS tags, and taints.

Show advanced settings

Parameter	Modifiable	Description
Resource Group		The resource group to which the cluster belongs. Each resource can belong to only one resource group. You can regard a resource group as a project, an application, or an organization based on your business scenarios.
ECS Tags		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 up to 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 labels apply only to newly added nodes and do not take effect on existing nodes in the node pool. If you want to modify the labels of existing nodes in the node pool, go to the ECS console and modify the labels of the ECS instances.
Taints		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		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 are end with `kubelet.kubernetes.io/`. Prefixes that are end with `node.kubernetes.io`. 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. 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 of 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. If 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 of 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 does not take effect on existing nodes in the node pool.
Custom Node Name		Specify whether to use a custom node name. If you choose to use a custom node name, the name of the node, name of the ECS instance, and hostname of the ECS instance are changed. Note If a Windows instance uses a custom node name, the hostname of the instance is fixed to an IP address. You need to use hyphens (`-`) to replace the periods (`.`) in the IP address. In addition, no prefix or suffix is allowed in the IP address. A custom node name consists of a prefix, an IP substring, and a suffix. A custom node name must be 2 to 64 characters in length. The name must start and end with a lowercase letter or digit. The prefix and suffix can contain letters, digits, hyphens (-), and periods (.). The prefix and suffix must start with a letter and cannot end with a hyphen (-) or period (.). The prefix and suffix cannot contain consecutive hyphens (-) or periods (.). The prefix is required due to ECS limits and the suffix is optional. For example, the node IP address is 192.XX.YY.55, the prefix is aliyun.com, and the suffix is test. If the node is a Linux node, the node name, ECS instance name, and ECS instance hostname are aliyun.com192.XX.YY.55test. If the node is a Windows node, the ECS instance hostname is 192-XX-YY-55 and the node name and ECS instance name are aliyun.com192.XX.YY.55test.
Pre-defined Custom Data		To use this feature, submit an application in the Quota Center console. Nodes automatically run predefined scripts before 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 echo "hello world" [Node initialization script]`
User Data		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.
CloudMonitor Agent		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.
Public IP		Specify whether to assign 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 EIP and associate the EIP with the node. For more information, see Associate an EIP with an ECS instance.
RDS Whitelist		Click Select RDS Instance to add node IP addresses to the whitelist of an ApsaraDB RDS instance.
Private Pool Type		Note This parameter is in canary release. To use this feature, submit a ticket. Valid values: Open, Do Not Use, and Specified. Open: The system automatically matches an open private pool. If no matching is found, resources in the public pool are used. Do Not Use: No private pool is used. Only resources in the public pool are used. Specified: Specify a private pool by ID. If the specified private pool is unavailable, ECS instances fail to start up. For more information, see Private pools.

Click Confirm. On the Node Pools page, check the state of the node pool. If Updating is displayed in the Status column, the node pool is being modified. After the node pool is modified, Active is displayed in the Status column.

Container Service for Kubernetes:Modify a node pool

Precautions

Procedure

References