（2）提前拉取镜像如果直接采用kubeadm init来初始化 ， 中间会有系统自动拉取镜像的这一步骤 ， 这是比较慢的 ， 我建议分开来做 ， 所以这里就先提前拉取镜像 。 在master节点操作如下指令：
[root@master ~]# kubeadm config images pull --config kubeadm-init.yaml[config/images] Pulled registry.aliyuncs.com/google_containers/kube-apiserver:v1.18.0[config/images] Pulled registry.aliyuncs.com/google_containers/kube-controller-manager:v1.18.0[config/images] Pulled registry.aliyuncs.com/google_containers/kube-scheduler:v1.18.0[config/images] Pulled registry.aliyuncs.com/google_containers/kube-proxy:v1.18.0[config/images] Pulled registry.aliyuncs.com/google_containers/pause:3.1[config/images] Pulled registry.aliyuncs.com/google_containers/etcd:3.4.3-0[config/images] Pulled registry.aliyuncs.com/google_containers/coredns:1.6.5如果大家看到开头的两行warning信息（我这里没有打印） ， 不必担心 ， 这只是警告 ， 不影响我们完成实验 。
既然镜像已经拉取成功了 ， 那我们就可以直接开始初始化了 。
（3）初始化kubenetes的master节点执行如下命令：
[root@master ~]# kubeadm init --config kubeadm-init.yaml[init] Using Kubernetes version: v1.18.3[preflight] Running pre-flight checks [WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service' [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at [preflight] Pulling images required for setting up a Kubernetes cluster[preflight] This might take a minute or two, depending on the speed of your internet connection[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"[kubelet-start] Starting the kubelet[certs] Using certificateDir folder "/etc/kubernetes/pki"[certs] Generating "ca" certificate and key[certs] Generating "apiserver" certificate and key[certs] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.50.128][certs] Generating "apiserver-kubelet-client" certificate and key[certs] Generating "front-proxy-ca" certificate and key[certs] Generating "front-proxy-client" certificate and key[certs] Generating "etcd/ca" certificate and key[certs] Generating "etcd/server" certificate and key[certs] etcd/server serving cert is signed for DNS names [master localhost] and IPs [192.168.50.128 127.0.0.1 ::1][certs] Generating "etcd/peer" certificate and key[certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [192.168.50.128 127.0.0.1 ::1][certs] Generating "etcd/healthcheck-client" certificate and key[certs] Generating "apiserver-etcd-client" certificate and key[certs] Generating "sa" key and public key[kubeconfig] Using kubeconfig folder "/etc/kubernetes"[kubeconfig] Writing "admin.conf" kubeconfig file[kubeconfig] Writing "kubelet.conf" kubeconfig file[kubeconfig] Writing "controller-manager.conf" kubeconfig file[kubeconfig] Writing "scheduler.conf" kubeconfig file[control-plane] Using manifest folder "/etc/kubernetes/manifests"[control-plane] Creating static Pod manifest for "kube-apiserver"[control-plane] Creating static Pod manifest for "kube-controller-manager"W0629 21:47:51.70956839444 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"[control-plane] Creating static Pod manifest for "kube-scheduler"W0629 21:47:51.71137639444 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s[apiclient] All control plane components are healthy after 14.003225 seconds[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace[kubelet] Creating a ConfigMap "kubelet-config-1.17" in namespace kube-system with the configuration for the kubelets in the cluster[upload-certs] Skipping phase. Please see --upload-certs[mark-control-plane] Marking the node master as control-plane by adding the label "node-role.kubernetes.io/master=''"[mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule][bootstrap-token] Using token: abcdef.0123456789abcdef[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key[addons] Applied essential addon: CoreDNS[addons] Applied essential addon: kube-proxyYour Kubernetes control-plane has initialized successfully!To start using your cluster, you need to run the following as a regular user:mkdir -p $HOME/.kubesudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/configsudo chown $(id -u):$(id -g) $HOME/.kube/configYou should now deploy a pod network to the cluster.Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:Then you can join any number of worker nodes by running the following on each as root:kubeadm join 192.168.50.128:6443 --token abcdef.0123456789abcdef \--discovery-token-ca-cert-hash sha256:05b84c41152f72ca33afe39a7ef7fa359eec3d3ed654c2692b665e2c4810af3e