101 lines
2.2 KiB
Markdown
101 lines
2.2 KiB
Markdown
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# kubeadm工作原理
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## 初始化系统
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所有机器都需要初始化docker和kubelet。这是因为kubeadm依赖kubelet来启动Master组件，比如kube-apiserver、kube-manager-controller、kube-scheduler、kube-proxy等。
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## 安装master
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在初始化master时，只需要执行kubeadm init命令即可，比如
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```sh
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kubeadm init kubeadm init --pod-network-cidr 10.244.0.0/16 --kubernetes-version latest
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```
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这个命令会自动
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- 系统状态检查
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- 生成token
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- 生成自签名CA和可独断证书
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- 生成kubeconfig用于kubelet连接API server
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- 为Master组件生成Static Pod manifests，并放到`/etc/kubernetes/manifests`目录中
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- 配置RBAC并设置Master node只运行控制平面组件
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- 创建附加服务，比如kube-proxy和kube-dns
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## 配置Network plugin
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kubeadm在初始化时并不关心网络插件，默认情况下，kubelet配置使用CNI插件，这样就需要用户来额外初始化网络插件。
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### CNI bridge
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```sh
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mkdir -p /etc/cni/net.d
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cat >/etc/cni/net.d/10-mynet.conf <<-EOF
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{
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"cniVersion": "0.3.0",
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"name": "mynet",
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"type": "bridge",
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"bridge": "cni0",
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"isGateway": true,
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"ipMasq": true,
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"ipam": {
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"type": "host-local",
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"subnet": "10.244.0.0/16",
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"routes": [
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{ "dst": "0.0.0.0/0" }
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]
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}
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}
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EOF
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cat >/etc/cni/net.d/99-loopback.conf <<-EOF
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{
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"cniVersion": "0.3.0",
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"type": "loopback"
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}
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EOF
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```
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### flannel
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```sh
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kubectl create -f https://github.com/coreos/flannel/raw/master/Documentation/kube-flannel-rbac.yml
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kubectl create -f https://github.com/coreos/flannel/raw/master/Documentation/kube-flannel.yml
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```
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### weave
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```sh
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kubectl apply -f https://git.io/weave-kube-1.6
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```
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### calico
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```sh
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kubectl apply -f http://docs.projectcalico.org/v2.1/getting-started/kubernetes/installation/hosted/kubeadm/1.6/calico.yaml
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```
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## 添加Node
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```sh
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token=$(kubeadm token list | grep authentication,signing | awk '{print $1}')
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kubeadm join --token $token ${master_ip}
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```
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这包括以下几个步骤
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- 从API server下载CA
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- 创建本地证书，并请求API Server签名
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- 最后配置kubelet连接到API Server
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## 删除安装
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```
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kubeadm reset
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```
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## 参考文档
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- [kubeadm Setup Tool](https://kubernetes.io/docs/admin/kubeadm/)
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