Container Service for Kubernetes:Virtual node overview

How it works

In a standard ACK cluster, the kubelet schedules pods to ECS nodes in a node pool. Scaling out means waiting for new ECS instances to start — a process that takes minutes and can leave you with idle capacity during off-peak hours.

Virtual nodes remove this layer. A virtual node encapsulates compute resources by using the ack-virtual-node component, allowing you to deploy workloads without worrying about the underlying infrastructure. ECI is a serverless container service where each elastic container instance maps to one pod. To deploy applications, you only need to provide a container image and pay for the resources your containers consume.

With this architecture, you skip node provisioning entirely. Provide a container image, and ECI handles the rest. You pay only for the resources your containers consume.

Benefits

Virtual nodes eliminate the infrastructure management that normally comes with handling variable workloads. With virtual nodes, you no longer need to:

• Select instance types or size node pools: No capacity planning required. Pods are created on demand and billed pay-as-you-go. When a pod terminates, billing stops.

• Perform node O&M: No OS updates, security patches, or node-level maintenance.

• Reserve resources for peak traffic: Scale to 50,000 pods in a single cluster without advance planning.

  Important

  If your pods are associated with many Services, keep the pod count below 20,000.

• Wait minutes for new capacity: Spin up thousands of pods within a short period of time to absorb traffic spikes.

• Manage cross-instance isolation: Each elastic container instance runs in a lightweight virtual sandbox, isolated from other instances.

Use cases

Limitations

Before using virtual nodes, check that your workloads are compatible.

Billing

The virtual node feature itself is free. The following charges apply when you use it:

• ACK cluster management fee: Charged for the ACK cluster.

• Elastic Container Instance: Charged for the resources consumed by pods running on ECI.

• Supporting services: Virtual Private Cloud (VPC) and Server Load Balancer (SLB) are billed separately.

For ECI pricing details, see Billing overview.

Quick start

To schedule your first pod to a virtual node, see Schedule pods to elastic container instances.

What's next

Before upgrading your cluster, make sure your ECI platform version is compatible with the target Kubernetes version. If incompatible ECI-based pods exist, delete and recreate them before upgrading. For details, see Update Elastic Container Instance platform version.