一、Kubernetes概述
1.1 Kubernetes是什么
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Kubernetes是Google在2014年开源的一个容器集群管理系统，Kubernetes简称K8S。
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K8S用于容器化应用程序的部署，扩展和管理。
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K8S提供了容器编排，资源调度，弹性伸缩，部署管理，服务发现等一系列功能。
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Kubernetes目标是让部署容器化应用简单高效。
1.2 Kubernetes特性
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自我修复
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在节点故障时重新启动失败的容器，替换和重新部署，保证预期的副本数量；杀死健康检查失败的容器，并且在未准备好之前不会处理客户端请求，确保线上服务不中断。
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弹性伸缩
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使用命令、UI或者基于CPU使用情况自动快速扩容和缩容应用程序实例，保证应用业务高峰并发时的高可用性；业务低峰时回收资源，以最小成本运行服务。
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自动部署和回滚
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K8S采用滚动更新策略更新应用，一次更新一个Pod，而不是同时删除所有Pod，如果更新过程中出现问题，将回滚更改，确保升级不受影响业务。
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服务发现和负载均衡
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K8S为多个容器提供一个统一访问入口（内部IP地址和一个DNS名称），并且负载均衡关联的所有容器，使得用户无需考虑容器IP问题。
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机密和配置管理
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管理机密数据和应用程序配置，而不需要把敏感数据暴露在镜像里，提高敏感数据安全性。并可以将一些常用的配置存储在K8S中，方便应用程序使用。
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存储编排
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挂载外部存储系统，无论是来自本地存储，公有云（如AWS），还是网络存储（如NFS、GlusterFS、Ceph）都作为集群资源的一部分使用，极大提高存储使用灵活性。
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批处理
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提供一次性任务，定时任务；满足批量数据处理和分析的场景。
1.3 Kubernetes集群架构与组件
1.4 Kubernetes集群组件介绍
1.4.1 Master组件
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kube-apiserver
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Kubernetes API，
集群的统一入口，各组件协调者，以RESTful API提供接口服务，所有对象资源的增删改查和监听操作都交给APIServer处理后再提交给Etcd存储。
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kube-controller-manager
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处理集群中常规后台任务，一个资源对应一个控制器，而ControllerManager就是负责管理这些控制器的。
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kube-scheduler
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根据调度算法为新创建的Pod选择一个Node节点，可以任意部署,可以部署在同一个节点上,也可以部署在不同的节点上。
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etcd
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分布式键值存储系统。用于保存集群状态数据，比如Pod、Service等对象信息。
1.4.2 Node组件
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kubelet
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kubelet是Master在Node节点上的Agent，管理本机运行容器的生命周期，比如创建容器、Pod挂载数据卷、下载secret、获取容器和节点状态等工作。kubelet将每个Pod转换成一组容器。
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kube-proxy
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在Node节点上实现Pod网络代理，维护网络规则和四层负载均衡工作。
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docker或rocket
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容器引擎，运行容器。
1.5 Kubernetes 核心概念
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Pod
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最小部署单元
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一组容器的集合
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一个Pod中的容器共享网络命名空间
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Pod是短暂的
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Controllers
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ReplicaSet ：确保预期的Pod副本数量
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Deployment ：无状态应用部署
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StatefulSet ：有状态应用部署
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DaemonSet ：确保所有Node运行同一个Pod
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Job ：一次性任务
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Cronjob ：定时任务
更高级层次对象，部署和管理Pod
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Service
- 防止Pod失联
- 定义一组Pod的访问策略
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Label ：标签，附加到某个资源上，用于关联对象、查询和筛选
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Namespaces：命名空间，将对象逻辑上隔离
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Annotations ：注释
二、kubeadm 快速部署K8S集群
2.1 kubernetes 官方提供的三种部署方式
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minikube
Minikube是一个工具，可以在本地快速运行一个单点的Kubernetes，仅用于尝试Kubernetes或日常开发的用户使用。部署地址：https://kubernetes.io/docs/setup/minikube/
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kubeadm
Kubeadm也是一个工具，提供kubeadm init和kubeadm join，用于快速部署Kubernetes集群。部署地址：https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/
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二进制包
推荐，从官方下载发行版的二进制包，手动部署每个组件，组成Kubernetes集群。下载地址：https://github.com/kubernetes/kubernetes/releases
2.2 安装kubeadm环境准备
以下操作,在三台节点都执行
2.2.1 环境需求
环境：centos 7.4 +
硬件需求：CPU>=2c ,内存>=2G
2.2.2 环境角色
| IP | 角色 | 安装软件 |
|---|---|---|
| 192.168.73.138 | k8s-Master | kube-apiserver kube-schduler kube-controller-manager docker flannel kubelet |
| 192.168.73.139 | k8s-node01 | kubelet kube-proxy docker flannel |
| 192.168.73.140 | k8s-node01 | kubelet kube-proxy docker flannel |
2.2.3 环境初始化
PS : 以下所有操作，在三台节点全部执行
1、关闭防火墙及selinux
$ sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config && setenforce 02、关闭 swap 分区
3、分别在192.168.73.138、192.168.73.139、192.168.73.140上设置主机名及配置hosts
$ hostnamectl set-hostname k8s-master（192.168.73.138主机打命令）
$ hostnamectl set-hostname k8s-node01（192.168.73.139主机打命令）$ hostnamectl set-hostname k8s-node02 (192.168.73.140主机打命令)4、在所有主机上上添加如下命令
$ cat >> /etc/hosts << EOF192.168.4.34 k8s-master192.168.4.35 k8s-node01192.168.4.36 k8s-node02EOF
5、内核调整,将桥接的IPv4流量传递到iptables的链
$ cat > /etc/sysctl.d/k8s.conf << EOFnet.bridge.bridge-nf-call-ip6tables = 1net.bridge.bridge-nf-call-iptables = 1EOF$ sysctl --system6、设置系统时区并同步时间服务器
2.2.4 docker 安装
$ wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo $ yum -y install docker-ce-18.06.1.ce-3.el7 $ systemctl enable docker && systemctl start docker $ docker --version Docker version 18.06.1-ce, build e68fc7a
2.2.5 添加kubernetes YUM软件源
$ cat > /etc/yum.repos.d/kubernetes.repo << EOF [kubernetes] name=Kubernetes baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=0 repo_gpgcheck=0 gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg EOF
2.2.6 安装kubeadm,kubelet和kubectl
2.2.6上所有主机都需要操作，由于版本更新频繁，这里指定版本号部署
$ yum install -y kubelet-1.15.0 kubeadm-1.15.0 kubectl-1.15.0 $ systemctl enable kubelet
2.3 部署Kubernetes Master
只需要在Master 节点执行，这里的apiserve需要修改成自己的master地址
[root@k8s-master ~]# kubeadm init --apiserver-advertise-address=192.168.73.138 --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.15.0 --service-cidr=10.1.0.0/16 --pod-network-cidr=10.244.0.0/16
由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。
输出结果:
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.1.0.1 192.168.4.34]
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.4.34 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.4.34 127.0.0.1 ::1]
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
......(省略)
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
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 192.168.73.138:6443 --token 2nm5l9.jtp4zwnvce4yt4oj
--discovery-token-ca-cert-hash sha256:12f628a21e8d4a7262f57d4f21bc85f8802bb717d
根据输出提示操作：
[root@k8s-master ~]# mkdir -p $HOME/.kube [root@k8s-master ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config [root@k8s-master ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
默认token的有效期为24小时，当过期之后，该token就不可用了，
如果后续有nodes节点加入，解决方法如下：
重新生成新的token
kubeadm token create [root@k8s-master ~]# kubeadm token create 0w3a92.ijgba9ia0e3scicg [root@k8s-master ~]# kubeadm token list TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS 0w3a92.ijgba9ia0e3scicg 23h 2019-09-08T22:02:40+08:00 authentication,signing <none> system:bootstrappers:kubeadm:default-node-token t0ehj8.k4ef3gq0icr3etl0 22h 2019-09-08T20:58:34+08:00 authentication,signing The default bootstrap token generated by 'kubeadm init'. system:bootstrappers:kubeadm:default-node-token [root@k8s-master ~]#
获取ca证书sha256编码hash值
[root@k8s-master ~]# openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //' ce07a7f5b259961884c55e3ff8784b1eda6f8b5931e6fa2ab0b30b6a4234c09a
节点加入集群
[root@k8s-node01 ~]# kubeadm join --token aa78f6.8b4cafc8ed26c34f --discovery-token-ca-cert-hash sha256:0fd95a9bc67a7bf0ef42da968a0d55d92e52898ec37c971bd77ee501d845b538 192.168.73.138:6443 --skip-preflight-chec
2.4 加入Kubernetes Node
在两个 Node 节点执行
使用kubeadm join 注册Node节点到Matser
kubeadm join 的内容，在上面kubeadm init 已经生成好了
[root@k8s-node01 ~]# kubeadm join 192.168.4.34:6443 --token 2nm5l9.jtp4zwnvce4yt4oj
--discovery-token-ca-cert-hash sha256:12f628a21e8d4a7262f57d4f21bc85f8802bb717dd6f513bf9d33f254fea3e89
输出内容：
[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-1.15" 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.
2.5 安装网络插件
只需要在Master 节点执行
[
修改镜像地址：(有可能默认不能拉取，确保能够访问到quay.io这个registery,否则修改如下内容)[进入编辑，把106行，120行的内容，替换如下image，替换之后查看如下为正确
[root@k8s-master ~]# cat -n kube-flannel.yml|grep lizhenliang/flannel:v0.11.0-amd64 106 image: lizhenliang/flannel:v0.11.0-amd64 120 image: lizhenliang/flannel:v0.11.0-amd64 [root@k8s-master ~]# kubectl apply -f kube-flannel.yml [root@k8s-master ~]# ps -ef|grep flannel root 2032 2013 0 21:00 ? 00:00:00 /opt/bin/flanneld --ip-masq --kube-subnet-mgr
查看集群的node状态，安装完网络工具之后，只有显示如下状态，所有节点全部都Ready好了之后才能继续后面的操作
[root@k8s-master ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master Ready master 37m v1.15.0 k8s-node01 Ready <none> 5m22s v1.15.0 k8s-node02 Ready <none> 5m18s v1.15.0 [root@k8s-master ~]# kubectl get pod -n kube-system NAME READY STATUS RESTARTS AGE coredns-bccdc95cf-h2ngj 1/1 Running 0 14m coredns-bccdc95cf-m78lt 1/1 Running 0 14m etcd-k8s-master 1/1 Running 0 13m kube-apiserver-k8s-master 1/1 Running 0 13m kube-controller-manager-k8s-master 1/1 Running 0 13m kube-flannel-ds-amd64-j774f 1/1 Running 0 9m48s kube-flannel-ds-amd64-t8785 1/1 Running 0 9m48s kube-flannel-ds-amd64-wgbtz 1/1 Running 0 9m48s kube-proxy-ddzdx 1/1 Running 0 14m kube-proxy-nwhzt 1/1 Running 0 14m kube-proxy-p64rw 1/1 Running 0 13m kube-scheduler-k8s-master 1/1 Running 0 13m
只有全部都为1/1则可以成功执行后续步骤，如果flannel需检查网络情况，重新进行如下操作kubectl delete -f kube-flannel.yml然后重新wget，然后修改镜像地址，然后kubectl apply -f kube-flannel.yml2.7 测试Kubernetes集群
在Kubernetes集群中创建一个pod，然后暴露端口，验证是否正常访问：
[root@k8s-master ~]# kubectl create deployment nginx --image=nginx deployment.apps/nginx created [root@k8s-master ~]# kubectl expose deployment nginx --port=80 --type=NodePort service/nginx exposed [root@k8s-master ~]# kubectl get pods,svc NAME READY STATUS RESTARTS AGE pod/nginx-554b9c67f9-wf5lm 1/1 Running 0 24s NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/kubernetes ClusterIP 10.1.0.1 <none> 443/TCP 39m service/nginx NodePort 10.1.224.251 <none> 80:31745/TCP 9
访问地址：http://NodeIP:Port ,此例就是：http://192.168.73.138:32039
2.8 部署 Dashboard
[root@k8s-master ~]# wget https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml [root@k8s-master ~]# vim kubernetes-dashboard.yaml 修改内容： 109 spec: 110 containers: 111 - name: kubernetes-dashboard 112 image: lizhenliang/kubernetes-dashboard-amd64:v1.10.1 # 修改此行 ...... 157 spec: 158 type: NodePort # 增加此行 159 ports: 160 - port: 443 161 targetPort: 8443 162 nodePort: 30001 # 增加此行 163 selector: 164 k8s-app: kubernetes-dashboard [root@k8s-master ~]# kubectl apply -f kubernetes-dashboard.yaml
在火狐浏览器访问(google受信任问题不能访问)地址： https://NodeIP:30001
创建service account并绑定默认cluster-admin管理员集群角色：
[root@k8s-master ~]# kubectl create serviceaccount dashboard-admin -n kube-system
serviceaccount/dashboard-admin created
[root@k8s-master ~]# kubectl create clusterrolebinding dashboard-admin --clusterrole=cluster-admin
--serviceaccount=kube-system:dashboard-admin
[root@k8s-master ~]# kubectl describe secrets -n kube-system $(kubectl -n kube-system get secret | awk '/dashboard-admin/{print $1}')
Name: dashboard-admin-token-d9jh2
Namespace: kube-system
Labels: <none>
Annotations: kubernetes.io/service-account.name: dashboard-admin
kubernetes.io/service-account.uid: 4aa1906e-17aa-4880-b848-8b3959483323
Type: kubernetes.io/service-account-token
Data
====
ca.crt: 1025 bytes
namespace: 11 bytes
token: eyJhbGciOiJ...(省略如下)...AJdQ
token: eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.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.OkF6h7tVQqmNJniCHJhY02G6u6dRg0V8PTiF8xvMuJJUphLyWlWctgmplM4kjKVZo0fZkAthL7WAV5p_AwAuj4LMfo1X5IpxUomp4YZyhqgsBM0A2ksWoKoLDjbizFwOty8TylWlsX1xcJXZjmP9OvNgjjSq5J90N5PnxYIIgwAMP3fawTP7kUXxz5WhJo-ogCijJCFyYBHoqHrgAbk9pusI8DpGTNIZxBMxkwPPwFwzNCOfKhD0c8HjhNeliKsOYLryZObRdmTQXmxsDfxynTKsRxv_EPQb99yW9GXJPQL0OwpYb4b164CFv857ENitvvKEOU6y55P9hFkuQuAJdQ
解决其他浏览器不能访问的问题
[root@k8s-master ~]# cd /etc/kubernetes/pki/ [root@k8s-master pki]# mkdir ui [root@k8s-master pki]# cp apiserver.crt ui/ [root@k8s-master pki]# cp apiserver.key ui/ [root@k8s-master pki]# cd ui/ [root@k8s-master ui]# mv apiserver.crt dashboard.pem [root@k8s-master ui]# mv apiserver.key dashboard-key.pem [root@k8s-master ui]# kubectl delete secret kubernetes-dashboard-certs -n kube-system [root@k8s-master ui]# kubectl create secret generic kubernetes-dashboard-certs --from-file=./ -n kube-system
[root@k8s-master]# vim kubernetes-dashboard.yaml #回到这个yaml的路径下修改
修改 dashboard-controller.yaml 文件，在args下面增加证书两行
- --tls-key-file=dashboard-key.pem
- --tls-cert-file=dashboard.pem
[root@k8s-master ~]kubectl apply -f kubernetes-dashboard.yaml
[root@k8s-master ~]# kubectl create serviceaccount dashboard-admin -n kube-system
serviceaccount/dashboard-admin created
[root@k8s-master ~]# kubectl create clusterrolebinding dashboard-admin --clusterrole=cluster-admin
--serviceaccount=kube-system:dashboard-admin
[root@k8s-master ~]# kubectl describe secrets -n kube-system $(kubectl -n kube-system get secret | awk '/dashboard-admin/{print $1}')
Name: dashboard-admin-token-zbn9f
Namespace: kube-system
Labels: <none>
Annotations: kubernetes.io/service-account.name: dashboard-admin
kubernetes.io/service-account.uid: 40259d83-3b4f-4acc-a4fb-43018de7fc19
Type: kubernetes.io/service-account-token
Data
====
namespace: 11 bytes
token: eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.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.E0hGAkeQxd6K-YpPgJmNTv7Sn_P_nzhgCnYXGc9AeXd9k9qAcO97vBeOV-pH518YbjrOAx_D6CKIyP07aCi_3NoPlbbyHtcpRKFl-lWDPdg8wpcIefcpbtS6uCOrpaJdCJjWFcAEHdvcfmiFpdVVT7tUZ2-eHpRTUQ5MDPF-c2IOa9_FC9V3bf6XW6MSCZ_7-fOF4MnfYRa8ucltEIhIhCAeDyxlopSaA5oEbopjaNiVeJUGrKBll8Edatc7-wauUIJXAN-dZRD0xTULPNJ1BsBthGQLyFe8OpL5n_oiHM40tISJYU_uQRlMP83SfkOpbiOpzuDT59BBJB57OQtl3w
ca.crt: 1025 bytes