问题1 

 [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/
error execution phase preflight: [preflight] Some fatal errors occurred:
        [ERROR Port-10251]: Port 10251 is in use
        [ERROR Port-10252]: Port 10252 is in use
        [ERROR FileContent--proc-sys-net-ipv4-ip_forward]: /proc/sys/net/ipv4/ip_forward contents are not set to 1
        [ERROR Port-10250]: Port 10250 is in use

  解决方法：

echo "echo 1 > /proc/sys/net/ipv4/ip_forward" >> /etc/rc.d/rc.local \
&& echo 1 > /proc/sys/net/ipv4/ip_forward \
&& chmod +x /etc/rc.d/rc.local \
&& ll /etc/rc.d/rc.local \
&& cat /proc/sys/net/ipv4/ip_forward

问题2 

[root@k8s-master ~]# kubectl get pod
The connection to the server localhost:8080 was refused - did you specify the right host or port?

解决方法： 

关闭防火墙
$ systemctl stop firewalld
$ systemctl disable firewalld

关闭swap
$ swapoff -a $ 临时
$ vim /etc/fstab $ 永久

问题3

Unable to update cni config: No networks found in /etc/cni/net.d

 解决方法： 

安装flannel
$ kubectl apply -f kube-flannel.yml

问题4  重启master后

k8s-master   NotReady   master   26h    v1.15.0

解决方法： 

$ systemctl restart kubelet