CNI插件的选择比较多，通常在非大规模集群中，我们可以有把握的说，所有的节点都会在同一个VPC中，各个节点之间的通信不需要跨路由，这种场景我个人推荐简单的 flannel 插件的 host-gw 模式。

为了方便，此处选择安装Flannel作为插件，github地址:https://github.com/coreos/flannel

安装指导: https://github.com/coreos/flannel/blob/master/Documentation/kubernetes.md

Flannel的网络模式：https://github.com/flannel-io/flannel/blob/master/Documentation/backends.md

[root@maxiaoke flannel]# wget https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml
# 需要修改一下内容：
# 1. Network 必须要是Pod CIDR,这个在 kubeadm init 时指定的
# 2. Type 是指flannel backend，推荐使用 host-gw
# 3. flannel 的镜像，当前版本默认使用的是 rancher 仓库，这里就不再修改了
[root@maxiaoke flannel]# grep -Ew "Type|image|Network" kube-flannel.yml 
      "Network": "10.200.0.0/16",
        "Type": "host-gw"
       #image: flannelcni/flannel-cni-plugin:v1.0.1 for ppc64le and mips64le (dockerhub limitations may apply)
        image: rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.1
       #image: flannelcni/flannel:v0.17.0 for ppc64le and mips64le (dockerhub limitations may apply)
        image: rancher/mirrored-flannelcni-flannel:v0.17.0
       #image: flannelcni/flannel:v0.17.0 for ppc64le and mips64le (dockerhub limitations may apply)
        image: rancher/mirrored-flannelcni-flannel:v0.17.0
[root@maxiaoke flannel]# kubectl apply -f kube-flannel.yml

[root@maxiaoke deploy-kubernetes]# kubectl get node -o wide
NAME        STATUS   ROLES                  AGE   VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
master-81   Ready    control-plane,master   9h    v1.23.6   10.4.7.81     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
worker-84   Ready    <none>                 9h    v1.23.6   10.4.7.84     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
worker-85   Ready    <none>                 9h    v1.23.6   10.4.7.85     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
worker-86   Ready    <none>                 9h    v1.23.6   10.4.7.86     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
worker-87   Ready    <none>                 9h    v1.23.6   10.4.7.87     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
worker-88   Ready    <none>                 9h    v1.23.6   10.4.7.88     <none>        CentOS Linux 7 (Core)   5.4.203-1.el7.elrepo.x86_64   containerd://1.6.4
[root@maxiaoke deploy-kubernetes]# kubectl get pod -n kube-system | grep core  # coredns 可以正常运行了
coredns-6d8c4cb4d-mqgk4             1/1     Running   0             25m
coredns-6d8c4cb4d-nxr8r             1/1     Running   0             9h