cloud-container-engine/umn/source/nodes/node_overview/container_engine.rst

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cce_10_0462.html

Container Engine

Introduction to Container Engines

Container engines, one of the most important components of Kubernetes, manage the lifecycle of images and containers. The kubelet interacts with a container runtime through the Container Runtime Interface (CRI).

Mapping between Node OSs and Container Engines

Table 1 Node OSs and container engines in CCE clusters

OS	Kernel Version	Container Engine	Container Storage Rootfs	Container Runtime
CentOS 7.x	3.x	Docker Clusters of v1.23 and later support containerd.	Clusters of v1.19.16 and earlier use Device Mapper. Clusters of v1.19.16 and later use OverlayFS.	runC
EulerOS 2.5	3.x	Docker	Device Mapper	runC
EulerOS 2.9	4.x	Docker Clusters of v1.23 and later support containerd.	OverlayFS	runC

Table 2 Node OSs and container engines in CCE Turbo clusters

Node Type	OS	Kernel Version	Container Engine	Container Storage Rootfs	Container Runtime
Elastic Cloud Server (VM)	CentOS 7.x EulerOS 2.9	3.x	Docker	OverlayFS	runC
Elastic Cloud Server (physical machine)	EulerOS 2.9	4.x	containerd	Device Mapper	Kata

Differences in Tracing

• Docker (Kubernetes 1.23 and earlier versions):

  kubelet --> docker shim (in the kubelet process) --> docker --> containerd

• Docker (community solution for Kubernetes v1.24 or later):

  kubelet --> cri-dockerd (kubelet uses CRI to connect to cri-dockerd) --> docker--> containerd

• containerd:

  kubelet --> cri plugin (in the containerd process) --> containerd

Although Docker has added functions such as swarm cluster, docker build, and Docker APIs, it also introduces bugs. Compared with containerd, Docker has one more layer of calling. Therefore, containerd is more resource-saving and secure.

Container Engine Version Description

• Docker
  • EulerOS/CentOS: docker-engine 18.9.0, a Docker version customized for CCE. Security vulnerabilities will be fixed in a timely manner.
• containerd: 1.4.1