Container Service for Kubernetes:Create and manage node pools

Console operations

On the Node Pools page of the cluster that you want to manage in the ACK console, you can create, edit, or delete a node pool. You can also view the details of a node pool.

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

2. On the Clusters page, find the cluster to manage and click its name. In the left-side navigation pane, choose Nodes > Node Pools.

Create a node pool

When you create a node pool in the ACK console, you can configure the basic, network, and storage configurations. Some node pool parameters, especially the parameters related to the node pool availability and network, cannot be modified after the node pool is created. The following tables describe these parameters. Creating a node pool in a cluster does not affect the nodes and applications deployed in other node pools of the cluster.

1. On the Node Pools page, click Create Node Pool. In the Create Node Pool dialog box, configure the node pool parameters.

   After you create the node pool, you can modify the node pool parameters on the Edit Node Pool page. The Modifiable column in the following tables indicates whether the corresponding parameter can be modified after the node pool is created. indicates that the parameter cannot be modified. indicates that the parameter can be modified.

   Basic configurations

   Parameter		Description	Modifiable
   Node Pool Name		Specify a node pool name.
   Region		By default, the region in which the cluster resides is selected. You cannot change the region.
   Scaling Mode		Manual and Auto are supported. Computing resources are automatically adjusted based on your business requirements and policies to reduce cluster costs. Manual: Container Service for Kubernetes (ACK) adjusts the number of nodes in the node pool based on the value of the Expected Nodes parameter. The number of nodes is always the same as the value of the Expected Nodes parameter. For more information, see Manually scale a node pool. Auto: When the capacity planning of the cluster cannot meet the requirements of pod scheduling, ACK automatically scales out nodes based on the configured minimum and maximum number of instances. By default, node instant scaling is enabled for clusters that run Kubernetes 1.24 and later. By default, node auto scaling is enabled for clusters that run Kubernetes 1.24 and later. For more information, see Node scaling.

   Network settings

   Parameter		Description	Modifiable
   Network Settings	VPC	By default, the virtual private cloud (VPC) in which the cluster resides is selected. You cannot change the VPC.
   	vSwitch	When the node pool is being scaled out, new nodes are created in the zones of the selected vSwitches based on the policy that you select for the Scaling Policy parameter. You can select vSwitches in the zones that you want to use. If no vSwitch is available, click Create vSwitch to create one. For more information, see Create and manage a vSwitch.

   Instance and image configurations

   Parameter	Description	Modifiable
   Billing Method	The default billing method used when ECS instances are scaled in a node pool. You can select Pay-As-You-Go, Subscription, or Preemptible Instance. If you select the Subscription billing method, you must configure the Duration parameter and choose whether to enable Auto Renewal. Preemptible Instance: ACK supports only Preemptible Instance with a protection period. You must also configure the Upper Price Limit of Current Instance Spec parameter. 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. For more information, see Best practices for preemptible instance-based node pools. 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 from pay-as-you-go or subscription to preemptible instances. For example, you cannot switch the billing method of a node pool between pay-as-you-go or subscription and preemptible instances. Important 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. To ensure that all nodes use the same billing method, ACK does not allow you to change the billing method of a node pool from pay-as-you-go or subscription to preemptible instances, or change the billing method of a node pool from preemptible instances to pay-as-you-go or subscription.
   Instance-related parameters	Select the ECS instances used by the worker node pool based on instance types or attributes. You can filter instance families by attributes such as vCPU, memory, instance family, and architecture. For more information about how to configure nodes, see ECS specification recommendations for ACK clusters. 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 check the scalability of the node pool when you create the node pool or after you create the node pool.
   Operating System	Alibaba Cloud Marketplace images is in canary release. Public Image: Alibaba Cloud Linux 3 Container-optimized images, ContainerOS, Alibaba Cloud Linux 3, Ubuntu, and Windows public images provided by Container Service for Kubernetes. For more information, see OS images. Custom Image: Use a custom operating system image. For more information, see How do I create a custom image based on an existing ECS instance and use it to create nodes? 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 upgrade or change the operating system, see Change the operating system. 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.
   Security Hardening	Enable security hardening for the cluster. You cannot modify this parameter after the cluster is created. Disable: disables security hardening for ECS instances. MLPS Security Hardening: Alibaba Cloud provides baselines and the baseline check feature to help you check the compliance of Alibaba Cloud Linux 2 images and Alibaba Cloud Linux 3 images with the level 3 standards of Multi-Level Protection Scheme (MLPS) 2.0. MLPS Security Hardening enhances the security of OS images to meet the requirements of GB/T 22239-2019 Information Security Technology - Baseline for Classified Protection of Cybersecurity without compromising the compatibility and performance of the OS images. For more information, see ACK security hardening based on MLPS. Important After you enable MLPS Security Hardening, remote logons through SSH are prohibited for root users. You can use Virtual Network Computing (VNC) to log on to the OS from the ECS console and create regular users that are allowed to log on through SSH. For more information, see Connect to an instance by using VNC. OS Security Hardening: You can enable Alibaba Cloud Linux Security Hardening only when the system image is an Alibaba Cloud Linux 2 or Alibaba Cloud Linux 3 image.
   Logon Type	If you select MLPS Security Hardening, only the Password option is supported. Key Pair and Password are supported. 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. Configure the Username (select root or ecs-user as the username) and the Key Pair parameters. Password: The password must be 8 to 30 characters in length, and can contain letters, digits, and special characters. Configure the Username (select root or ecs-user as the username) and the Password parameters.
   Username	If you select Key Pair or Password for Logon Type, you must select root or ecs-user as the username.

   Storage configurations

   Parameter	Description	Modifiable
   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 vary based on the instance families that you select. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select. ESSD custom performance and encryption If you select Enterprise SSD (ESSD), you can set a custom performance level. You can select higher performance levels (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 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 Bring Your Own Key (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.
   Data Disk	ESSD AutoPL, Enterprise SSD (ESSD), ESSD Entry, SSD, and Ultra Disk are supported. The data disk types that you can select vary based on the instance families that you select. Disk types that are not displayed in the drop-down list are not supported by the instance types that you select. ESSD AutoPL Disk 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. Enterprise SSD (ESSD) Configure a custom performance level. 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 Up to 64 data disks can be attached to an ECS instance. The number of disks that can be attached to an ECS instance varies based on the instance type. To query the maximum number of data disks supported by each instance type, call the DescribeInstanceTypes operation and query the DiskQuantity parameter in the response.

   Instance quantity

   Parameter	Description	Modifiable
   Expected Nodes	The expected number of nodes in the node pool. We recommend that you configure at least two nodes to ensure that cluster components run as expected. You can configure the Expected Nodes parameter to adjust the number of nodes in the node pool. For more information, see Manually scale node pools. If you do not want to create nodes in the node pool, set this parameter to 0. You can manually modify this parameter to add nodes later.

   Advanced settings

   Click Advanced Options (Optional) and configure the node scaling policy, resource group, ECS tags, and taints.

   Advanced options

   Parameter	Description	Modifiable
   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.
   Scaling Mode	You must select Auto for the Scaling Mode. Standard mode: Auto scaling is implemented by creating and releasing ECS instances. Swift mode: Auto scaling is implemented by creating, stopping, and starting ECS instances. ECS instances in the Stopped state can be directly restarted to accelerate scaling activities. When a node in swift mode is reclaimed, only disk fees are charged for the node. No computing fee is charged. This rule does not apply to instance families that use local disks, such as big data and local SSDs instance families. For more information about the billing rules and limits of the economical mode, see Economical mode.
   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. If the Billing Method of the node pool is set to Preemptible Instance, preemptible instances are preferentially created. You can also set the Percentage of Pay-as-you-go Instances parameter. If preemptible instances cannot be created due to reasons such as insufficient stocks, pay-as-you-go instances are automatically created as supplement. 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.
   Use Pay-as-you-go Instances When Preemptible Instances Are Insufficient	You must set the Billing Method parameter to Preemptible Instance. After this feature is enabled, if enough preemptible instances cannot be created because of price or inventory constraints, ACK automatically creates pay-as-you-go instances to meet the required number of ECS instances.
   Enable Supplemental Preemptible Instances	You must set the Billing Method parameter to Preemptible Instance. 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.
   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 at most 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 label 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. To meet 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.
   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.
   Node Labels	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: Key: The name 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 label 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 (/). 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. 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.
   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	After you install CloudMonitor, you can view the monitoring information about the nodes in the CloudMonitor console. 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 configure the Bandwidth Billing Method and Peak Bandwidth parameters. 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.
   Custom Security Group	You can select Basic Security Group or Advanced Security Group, but you can select only one security group type. You cannot modify the security groups of node pools or change the type of security group. For more information about security groups, see Overview. Important Each ECS instance supports up to five security groups. Make sure that the quota of security groups for your ECS instance is sufficient. For more information about security group limits and how to increase the quota limit of security groups for your ECS instance, see Security groups. If you select an existing security group, the system does not automatically configure security group rules. This may cause errors when you access the nodes in the cluster. You must manually configure security group rules. For more information about how to manage security group rules, see Configure security group rules to enforce access control on ACK clusters.
   RDS Whitelist	Add node IP addresses to the whitelist of an ApsaraDB RDS instance.
   Deployment Set	You must first create a deployment set in the ECS console and then specify the deployment set when you create a node pool in the ACK console. The deployment set cannot be modified after the cluster is created. You can use a deployment set to distribute your ECS instances to different physical servers to ensure high service availability and implement underlying disaster recovery. If you specify a deployment set when you create ECS instances, the instances are created and distributed based on the deployment strategy that you preset for the deployment set within the specified region. For more information, see Best practices for associating deployment sets with node pools. Important After you select a deployment set, the maximum number of nodes that can be created in the node pool is limited. By default, the maximum number of nodes supported by a deployment set is 20 × Number of zones. The number of zones depends on the number of vSwitches. Exercise caution when you select the deployment set. To avoid node creation failures, make sure that the ECS quota of the deployment set that you select is sufficient.
   Private Pool Type	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.

2. Click Confirm Order.

   In the node pool list, if the Status column of the node pool displays Initializing, the node pool is being created. After the node pool is created, the Status column of the node pool displays Active.

Modify a node pool

After you create a node pool, you can modify the configurations of the node pool in the ACK One registered cluster. For example, you can change the billing method, vSwitches, instance specifications, and system disks that are used by the node pool. You can also enable or disable auto scaling for the node pool. For more information about the parameters that can be modified, see Create a node pool.

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

2. In the dialog box that appears, modify the parameters of the node pool based on the on-screen instructions.

   On the Node Pools page, if the Status column of the node pool displays Updatng, the node pool is being modified. After the node pool is updated, the Status column displays Activated.

View a node pool

You can view the basic information, monitoring data, node information, and scaling events of a node pool in the ACK console.

Click the name of the node pool that you want to manage to view the following information on the details page of the node pool:

Delete a node pool

The release rules of an ECS instance vary based on the billing method of the instance. When you remove a node from a node pool, we recommend that you perform the operations described in the following table. Before you delete a node pool, check whether the Expected Nodes parameter is configured for the node pool. This parameter may affect the node release process.

1. Optional: Click the name of the node pool that you want to manage. On the Overview tab, you can check whether the Expected Nodes parameter is configured. If a hyphen (-) is displayed, the Expected Nodes parameter is not configured.

2. Select the node pool that you want to delete and choose More > Delete in the Actions. Read and confirm the information in the dialog box and then click OK.