Overview

Introduction

A container cluster consists of a set of worker machines, called nodes, that run containerized applications. A node can be a virtual machine (VM) or a physical machine (PM), depending on your service requirements. The components on a node include kubelet, container runtime, and kube-proxy.

A Kubernetes cluster consists of master nodes and node nodes. The nodes described in this section refer to worker nodes, the computing nodes of a cluster that run containerized applications.

CCE uses high-performance Elastic Cloud Servers (ECSs) as nodes to build highly available Kubernetes clusters.

Notes

To ensure node stability, a certain amount of CCE node resources will be reserved for Kubernetes components (such as kubelet, kube-proxy, and docker) based on the node specifications. Therefore, the total number of node resources and the amount of allocatable node resources for your cluster are different. The larger the node specifications, the more the containers deployed on the node. Therefore, more node resources need to be reserved to run Kubernetes components.
The node networking (such as the VM networking and container networking) is taken over by CCE. You are not allowed to add NICs or change routes. If you modify the networking configuration, the availability of CCE may be affected.

Node Lifecycle

A lifecycle indicates the node statuses recorded from the time when the node is created through the time when the node is deleted or released.

**Table 1** Node statuses
Status	Status Attribute	Description
Available	Stable state	The node is running properly and is connected to the cluster. Nodes in this state can provide services.
Unavailable	Stable state	The node is not running properly. Instances in this state no longer provide services. In this case, perform the operations in Resetting a Node.
Creating	Intermediate state	The node has been created but is not running.
Installing	Intermediate state	The Kubernetes software is being installed on the node.
Deleting	Intermediate state	The node is being deleted. If this state stays for a long time, an exception occurs.
Stopped	Stable state	The node is stopped properly. A node in this state cannot provide services. You can start the node on the ECS console.
Error	Stable state	The node is abnormal. Instances in this state no longer provide services. In this case, perform the operations in Resetting a Node.