使用 kubeadm 配置 slave 节点

概述

将 slave 节点加入到集群中很简单，只需要在 slave 服务器上安装 kubeadm，kubectl，kubelet 三个工具，然后使用kubeadm join 命令加入即可。准备工作如下：

• 修改主机名
• 配置软件源
• 安装三个工具
  由于之前章节已经说明了操作步骤，此处不再赘述。

将 slave 加入到集群

kubeadm join 192.168.141.130:6443 --token abcdef.0123456789abcdef --discovery-token-ca-cert-hash sha256:cab7c86212535adde6b8d1c7415e81847715cfc8629bb1d270b601744d662515

# 安装成功将看到如下信息
[preflight] Running pre-flight checks
        [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Activating the kubelet service
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

说明：

• token
  • 可以通过安装 master 时的日志查看 token 信息
  • 可以通过kubeadm token list 命令打印出 token 信息
  • 如果 token 过期，可以使用 kubeadm token create 命令创建新的 token
• discovery-token-ca-cert-hash
  • 可以通过安装 master 时的日志查看 sha256 信息
  • 可以通过 openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'命令查看 sha256 信息

验证是否成功

回到 master 服务器

kubectl get nodes

# 可以看到 slave 成功加入 master
NAME                STATUS     ROLES    AGE   VERSION
kubernetes-master   NotReady   master   9h    v1.14.1
kubernetes-slave1   NotReady      22s   v1.14.1

如果 slave 节点加入 master 时配置有问题可以在 slave 节点上使用 kubeadm reset 重置配置再使用 kubeadm join 命令重新加入即可。希望在 master 节点删除 node ，可以使用 kubeadm delete nodes 删除。

查看 pod 状态

kubectl get pod -n kube-system -o wide

NAME                                        READY   STATUS    RESTARTS   AGE   IP                NODE                NOMINATED NODE   READINESS GATES
coredns-8686dcc4fd-gwrmb                    0/1     Pending   0          9h                                         
coredns-8686dcc4fd-j6gfk                    0/1     Pending   0          9h                                         
etcd-kubernetes-master                      1/1     Running   1          9h    192.168.141.130   kubernetes-master              
kube-apiserver-kubernetes-master            1/1     Running   1          9h    192.168.141.130   kubernetes-master              
kube-controller-manager-kubernetes-master   1/1     Running   1          9h    192.168.141.130   kubernetes-master              
kube-proxy-496dr                            1/1     Running   0          17m   192.168.141.131   kubernetes-slave1              
kube-proxy-rsnb6                            1/1     Running   1          9h    192.168.141.130   kubernetes-master              
kube-scheduler-kubernetes-master            1/1     Running   1          9h    192.168.141.130   kubernetes-master              

由此可以看出 coredns 尚未运行，此时我们还需要安装网络插件。