关机一段时间后k8s无法启动

• 重装前清除环境方法：
• 重装后pod-coredns一直处于ContainerCreating状态:

重启之后k8s集群居然起不起来了
解决方法：重装

重装前清除环境方法：

kubeadm reset
systemctl stop kubelet
systemctl stop docker
rm -rf /var/lib/cni/ /var/lib/kubelet/* /etc/cni/
ifconfig cni0 down
ifconfig flannel.1 down
ifconfig docker0 down
ip link delete cni0
ip link delete flannel.1
systemctl start docker
# kubeadm join xxx

重装后pod-coredns一直处于ContainerCreating状态:

看是否重装了Pod Network

$ curl -O https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

如果node有多个网卡,需编辑kube-flannel.yml,用--iface指定网卡

containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.11.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1

apply kube-flannel

$ kubectl apply -f  kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

但是仍然pod-coredns一直处于ContainerCreating状态
kubectl describe pod一下，发现是/var/lib/cni找不到

mkdir -p /etc/cni/net.d

cat > /etc/cni/net.d/10-flannel.conflist << EOF
{
  "name": "cbr0",
  "plugins": [
    {
      "type": "flannel",
      "delegate": {
        "hairpinMode": true,
        "isDefaultGateway": true
      }
    },
    {
      "type": "portmap",
      "capabilities": {
        "portMappings": true
      }
    }
  ]
}
EOF

然后重启kubectl，发现还是不行。
再修改/run/flannel/subnet.env

$ vim /run/flannel/subnet.env
FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.0.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

保存再重启kubectl，终于可以了。
也许本来就只需要改/run/flannel/subnet.env文件。不过现在已经无法验证了。
只能等下次出问题再验证。

参考网址：
https://blog.csdn.net/ANXIN997483092/article/details/86711006
https://blog.csdn.net/qq_26545503/article/details/123183184
https://www.cnblogs.com/aresxin/p/K8S-issue1.html