# kubeadm init --config kubeadm.yaml --ignore-preflight-errors=Swap
..........
Your Kubernetes control-plane has initialized successfully! To start using your cluster, you need to run the following as a regular user:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
You should now deploy a pod network to the cluster. Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: https://kubernetes.io/docs/concepts/cluster-administration/addons/ Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.1.21:6443 --token 4qcl2f.gtl3h8e5kjltuo0r \ --discovery-token-ca-cert-hash sha256:7ed5404175cc0bf18dbfe53f19d4a35b1e3d40c19b10924275868ebf2a3bbe6e
注意这一条命令需要保存好（添加集群使用）
kubeadm join 192.168.169.21:6443 –token 4qcl2f.gtl3h8e5kjltuo0r \ –discovery-token-ca-cert-hash sha256:7ed5404175cc0bf18dbfe53f19d4a35b1e3d40c19b10924275868ebf2a3bbe6e
上面记录了完成的初始化输出的内容，根据输出的内容基本上可以看出手动初始化安装一个Kubernetes集群所需要的关键步骤。 其中有以下关键内容：
[kubelet-start] 生成kubelet的配置文件”/var/lib/kubelet/config.yaml”
[certs]生成相关的各种证书
[kubeconfig]生成相关的kubeconfig文件
[control-plane]使用/etc/kubernetes/manifests目录中的yaml文件创建apiserver、controller-manager、scheduler的静态pod
[bootstraptoken]生成token记录下来，后边使用kubeadm join往集群中添加节点时会用到
下面的命令是配置常规用户如何使用kubectl访问集群：
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
最后给出了将节点加入集群的命令kubeadm join 192.168.169.21:6443 –token 4qcl2f.gtl3h8e5kjltuo0r \ –discovery-token-ca-cert-hash sha256:7ed5404175cc0bf18dbfe53f19d4a35b1e3d40c19b10924275868ebf2a3bbe6e
查看一下集群状态，确认个组件都处于healthy状态：
# kubectl get cs
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-0 Healthy {"health":"true"}
集群初始化如果遇到问题，可以使用下面的命令进行清理：
# kubeadm reset
# ifconfig cni0 down
# ip link delete cni0
# ifconfig flannel.1 down
# ip link delete flannel.1
# rm -rf /var/lib/cni/
3.3 安装Pod Network
接下来安装flannel network add-on：
# mkdir -p ~/k8s/
# cd ~/k8s
# curl -O https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
# 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
这里注意kube-flannel.yml这个文件里的flannel的镜像是0.11.0，quay.io/coreos/flannel:v0.11.0-amd64
如果Node有多个网卡的话，参考flannel issues 39701，目前需要在kube-flannel.yml中使用–iface参数指定集群主机内网网卡的名称，否则可能会出现dns无法解析。需要将kube-flannel.yml下载到本地，flanneld启动参数加上–iface=<iface-name>
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
......
使用kubectl get pod –all-namespaces -o wide确保所有的Pod都处于Running状态。
# kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-5c98db65d4-dr8lf 1/1 Running 0 52m
coredns-5c98db65d4-lp8dg 1/1 Running 0 52m
etcd-node1 1/1 Running 0 51m
kube-apiserver-node1 1/1 Running 0 51m
kube-controller-manager-node1 1/1 Running 0 51m
kube-flannel-ds-amd64-mm296 1/1 Running 0 44s
kube-proxy-kchkf 1/1 Running 0 52m
kube-scheduler-node1 1/1 Running 0 51m
3.4 测试集群DNS是否可用