error execution phase preflight: [preflight] Some fatal errors occurred:
[ERROR CRI]: container runtime is not running: output: time="2022-05-12T05:17:39-04:00" level=fatal msg="getting status of runtime: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
, error: exit status 1

rm /etc/containerd/config.toml
systemctl restart containerd
kubeadm init

[kubelet-check] It seems like the kubelet isn't running or healthy.
[kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused.

A2：Docker是用yum安装的，docker的cgroup驱动程序默认设置为systemd。默认情况下Kubernetes cgroup为system，需要更改Docker cgroup驱动，

添加以下内容
vim /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}

重启docker       systemctl restart docker

[root@k8smaster ~]# kubectl get pod
Unable to connect to the server: x509: certificate signed by unknown authority (possibly because of "crypto/rsa: verification error" while trying to verify candidate authority certificate "kubernetes")

先删除主目录下的kube目录：rm -rf  ~/.kube/

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config