一、背景
Kubernetes 自 v1.24 起移除了 dockershim，不再原生支持 Docker Engine，用户需迁移至受支持的 CRI 兼容运行时，如：
-
Containerd（推荐，高性能、轻量级）
-
CRI-O（专为 Kubernetes 设计）
-
Docker Engine + cri-dockerd（兼容方案，但需额外维护）
二、迁移步骤
1.前置准备
当前是3个node节点，都是docker运行时，现在驱逐node-3节点
#移除节点
[root@master-1 ~]# kubectl drain node-3 --ignore-daemonsets
#停止相关服务
[root@node-3 ~]# systemctl stop kubelet
[root@node-3 ~]# systemctl stop docker
[root@node-3 ~]# systemctl disable docker --now
[root@node-3 ~]# systemctl stop kube-proxy2.部署containerd服务
Containerd部署指南
3.修改kubelet参数
加上containerd运行时参数--container-runtime=remote --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock
[root@node-3 ~]# cat /usr/lib/systemd/system/kubelet.service
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/kubernetes/kubernetes
After=containerd.service
Requires=containerd.service
[Service]
WorkingDirectory=/var/lib/kubelet
ExecStart=/usr/local/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/cfg/kubelet-bootstrap.kubeconfig --cert-dir=/etc/kubernetes/ssl --kubeconfig=/etc/kubernetes/cfg/kubelet.config --config=/etc/kubernetes/cfg/kubelet.json --pod-infra-container-image=registry.aliyuncs.com/google_containers/pause:3.2 --alsologtostderr=true --logtostderr=false --log-dir=/var/log/kubernetes --container-runtime=remote --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock --v=2
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target4.启动各个服务
#启动服务
[root@node-3 ~]# systemctl daemon-reload
[root@node-3 ~]# systemctl restart kubelet
[root@node-3 ~]# systemctl start kube-proxy
[root@node-3 ~]# systemctl status kubelet
[root@node-3 ~]# systemctl status kube-proxy5.查看node-3节点状态
#目前节点3已经准备好啦，处于不可调度状态
[root@master-1 ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node-1 Ready <none> 71d v1.23.1
node-2 Ready <none> 71d v1.23.1
node-3 Ready,SchedulingDisabled <none> 24h v1.23.16.将node节点恢复为可调度
#恢复可调度状态
[root@master-1 ~]# kubectl uncordon node-3
node/node-3 uncordoned7.查看节点运行时
#发现运行时已经切换成功啦
[root@master-1 ~]# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
node-3 Ready <none> 24h v1.23.1 192.168.91.23 <none> CentOS Linux 7 (Core) 3.10.0-862.el7.x86_64 containerd://1.6.48.测试业务
部署一个nginx业务
[root@master-1 ~]# cat nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-demo
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:latest
imagePullPolicy: IfNotPresent
[root@master-1 ~]# kubectl apply -f nginx.yaml
[root@master-1 ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-demo-68984b745f-5k5ts 1/1 Running 0 7m14s 10.244.1.2 node-2 <none> <none>
nginx-demo-68984b745f-9pmwk 1/1 Running 0 29m 10.244.2.56 node-3 <none> <none>
nginx-demo-68984b745f-bp8x2 1/1 Running 0 7m14s 10.244.0.2 node-1 <none> <none>以上效果说明我们集群已从 Docker 全面切换至 Containerd，运行状态正常。
