Deploy the virtual node controller and use it to create Elastic Container Instance-based pods - User Guide for Kubernetes Clusters| Alibaba Cloud Documentation Center

Virtual nodes enable seamless integration between Kubernetes and Elastic Container Instance. Virtual nodes empower Kubernetes clusters with high elasticity. This way, Kubernetes clusters are no longer limited by the computing capacity of cluster nodes. You can dynamically create Elastic Container Instance-based pods to meet your business requirements. This saves the trouble of cluster sizing. This topic describes virtual nodes and elastic container instances. It also describes how to deploy the virtual node controller (ack-virtual-node) and then use it to create Elastic Container Instance-based pods.

Prerequisites

A managed Kubernetes cluster or a dedicated Kubernetes cluster with a version later than V1.14 is created. For more information, see Create a managed Kubernetes cluster or Create a dedicated Kubernetes cluster.
Elastic Container Instance is activated. You can log on to the Elastic Container Instance console to activate the service.
The region where the cluster is deployed must be supported by elastic container instances. To view the supported regions and zones, log on to the Elastic Container Instance console.

Virtual nodes and elastic container instances

Elastic Container Instance is a serverless compute service that is provided by Alibaba Cloud for containerization. You can use elastic container instances to set up an operations and maintenance (O&M)-free and isolated runtime environment for your containers. Elastic container instances allow you to focus on containerized applications without the need to purchase or manage Elastic Compute Service (ECS) instances. This way, you do not need to perform infrastructure maintenance. You can create elastic container instances to meet your business requirements. You are charged for resource usage on a per second basis.

Virtual nodes enable seamless integration between Kubernetes and Elastic Container Instance. Virtual nodes empower Kubernetes clusters with high elasticity. This way, Kubernetes clusters are no longer limited by the computing capacity of cluster nodes. You can dynamically create Elastic Container Instance-based pods to meet your business requirements. This saves the trouble of cluster sizing. Virtual nodes can significantly reduce computing costs and improve cluster elasticity in the following scenarios:

Online business that requires elastic scaling to withstand traffic fluctuations, such as online education and e-commerce. Virtual nodes optimize the maintenance of resource pools. This can help you reduce computing costs.
Virtual nodes can reduce costs in computing scenarios where Spark or Presto is used to process data.
CI/CD pipeline: Jenkins and Gitlab-Runner.
Jobs: Jobs in Artificial Intelligence (AI) computing scenarios and CronJobs.

Based on virtual nodes and elastic container instances, ACK provides multiple serverless container services, such as serverless Kubernetes (ASK) and ACK on Elastic Container Instance. You can use these services to deploy elastic and maintenance-free workloads.

Step 1: Deploy ack-virtual-node in ACK clusters

Note

The virtual node controller ack-virtual-node is managed by ASK clusters. Therefore, you can create Elastic Container Instance-based pods in ASK clusters without the need to deploy ack-virtual-node. In managed or dedicated Kubernetes clusters, you must deploy ack-virtual-node before you can create Elastic Container Instance-based pods.
In managed Kubernetes clusters, you can deploy ack-virtual-node on the Add-ons page. By default, ack-virtual-node is managed by the clusters after it is deployed.
In dedicated Kubernetes clusters, you can deploy ack-virtual-node on the App Catalog page. By default, ack-virtual-node is managed by the clusters after it is deployed.

Managed Kubernetes clusters

Perform the following steps to deploy ack-virtual-node in a managed Kubernetes cluster:

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 the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
In the left-side navigation pane of the details page, choose Operations > Add-ons.
On the Add-ons page, select ack-virtual-node and click Install.
The default vSwitch and security group of the cluster are used for elastic container instances that are deployed by ack-virtual-node. If you want to modify these settings, see What to do next.

Dedicated Kubernetes Clusters

Perform the following steps to deploy ack-virtual-node in a dedicated Kubernetes cluster:

Log on to the ACK console.
In the left-side navigation pane of the ACK console, choose Marketplace > App Catalog.
On the App Catalog page, click the Alibaba Cloud Apps tab and find and click ack-virtual-node.
In the upper-right corner of the App Catalog page, you can enter ack-virtual-node into the Name search bar and click the search icon. You can also enter a keyword to perform a fuzzy match.
On the App Catalog - ack-virtual-node page, select a cluster in the Deploy section.
Namespace is automatically set to kube-system and Release Name is automatically set to ack-virtual-node.

On the App Catalog - ack-virtual-node page, click the Parameters tab and set the parameters. Then, click Create in the Deploy section.


Parameter	Description	How to obtain the value
ALIYUN_CLUSTERID	The ID of the cluster where you want to deploy ack-virtual-node	On the details page of the cluster, click the Basic Information tab. In the Basic Information section, you can view the ID of the cluster.
ALIYUN_RESOURCEGROUP_ID	The ID of the resource group to which the cluster belongs	If you do not specify the parameter, the default resource group is used. To specify a resource group, log on to the Resource Management console to obtain the ID of the resource group.
ECI_REGION	The name of the region where the cluster is deployed	On the details page of the cluster, click the Basic Information tab. In the Basic Information section, you can view the Region where the cluster is deployed. Note For example, cn-hangzhou indicates the China (Hangzhou) region.
ECI_VSWITCH	vSwitches	On the Nodes page, click the ID of a node. On the Instance Details page, you can obtain the value of VSwtich in the Configuration Information section. Note Make sure that the zone of the vSwitch is supported by elastic compute instances. You can specify vSwitches that are deployed in different zones. For example, you can specify multiple vSwitches in the format of `ECI_VSWITCH: "vsw-xxxxxxx1, vsw-xxxxxxx2, vsw-xxxxxxx3"`.
ECI_SECURITY_GROUP	The ID of the security group to which nodes in the cluster belong	On the Nodes page, click the ID of a node. In the left-side navigation pane, click Security Groups. Click the Security Groups tab to obtain the ID of the security group.
ECI_ACCESS_KEY	The AccessKey ID of your Alibaba Cloud account	For more information, see Obtain an AccessKey pair. You must attach the AliyunECIReadOnlyAccess policy to your account in the RAM console. For more information, see Grant permissions to a RAM user.
ECI_SECRET_KEY	The AccessKey secret of your Alibaba Cloud account	For more information, see Obtain an AccessKey pair. You must attach the AliyunECIReadOnlyAccess policy to your account in the RAM console. For more information, see Grant permissions to a RAM user.

Run the following command to view the status of virtual-node-controller. For more information, see Use kubectl on Cloud Shell to manage ACK clusters.
Run the following command:
```
kubectl -n kube-system get deploy ack-virtual-node-controller
```
The following output is returned:
```
NAME                     READY   AGE
virtual-node-controller  1/1     1m
```

Step 2: Create Elastic Container Instance-based pods

Note All the pods in ASK clusters are Elastic Container Instance-based pods. You do not need to use labels to identify Elastic Container Instance-based pods. Therefore, the following operations do not apply to ASK clusters. The following operations show how to create an Elastic Container Instance-based pod in an ACK cluster.

You can use one of the following methods to create an Elastic Container Instance-based pod in an ACK cluster.

Add a label to the pod.
Add the alibabacloud.com/eci=true label to the pod. The pod becomes an Elastic Container Instance-based pod and is scheduled to the virtual node. Example:
Run the following command:
```
kubectl run nginx --image nginx -l alibabacloud.com/eci=true
```
```
kubectl get pod -o wide|grep virtual-kubelet
```
The following output is returned:
```
nginx-7fc9f746b6-r4xgx     0/1     ContainerCreating   0          20s   192.168. *.*   virtual-kubelet        <none>           <none>
```
Add a label to the namespace where the pod is deployed.
Add the alibabacloud.com/eci=true label to the namespace where the pod is deployed. The pod becomes an Elastic Container Instance-based pod and is scheduled to the virtual node. Example:
Run the following command:
```
kubectl create ns vk
```
```
kubectl label namespace vk alibabacloud.com/eci=true
```
```
kubectl -n vk run nginx --image nginx
```
```
kubectl -n vk get pod -o wide|grep virtual-kubelet
```
The following output is returned:
```
nginx-6f489b847d-vgj4d      1/1     Running             0          1m   192.168. *.*   virtual-kubelet        <none>           <none>
```

What to do next

Note The following operations only apply to ACK clusters and do not apply to ASK clusters.

Delete virtual nodes in ACK clusters

Uninstall ack-virtual-node.
- After you delete all the pods in a managed Kubernetes cluster, you can uninstall ack-virtual-node on the Add-ons page.
- After you delete all the Elastic Container Instance-based pods in a dedicated Kubernetes cluster, you can uninstall ack-virtual-node on the Helm page.
Run the kubectl delete no command to delete related virtual nodes.

Note If you do not delete the Elastic Container Instance-based pods in the cluster before you uninstall ack-virtual-node, the elastic container instances are retained in the cluster.