010.Kubernetes二进制部署kube-controller-manager

一 部署高可用kube-controller-manager

1.1 高可用kube-controller-manager介绍

本实验部署一个三实例 kube-controller-manager 的集群，启动后将通过竞争选举机制产生一个 leader 节点，其它节点为阻塞状态。当 leader 节点不可用时，阻塞的节点将再次进行选举产生新的 leader 节点，从而保证服务的可用性。

为保证通信安全，本文档先生成 x509 证书和私钥，kube-controller-manager 在如下两种情况下使用该证书：

• 与 kube-apiserver 的安全端口通信;
• 在安全端口(https，10252) 输出 prometheus 格式的 metrics。

1.2 创建kube-controller-manager证书和私钥

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# cat > kube-controller-manager-csr.json <<eof
  3 {
  4   "cn": "system:kube-controller-manager",
  5   "hosts": [
  6     "127.0.0.1",
  7     "172.24.8.71",
  8     "172.24.8.72",
  9     "172.24.8.73"
 10   ],
 11   "key": {
 12     "algo": "rsa",
 13     "size": 2048
 14   },
 15   "names": [
 16     {
 17       "c": "cn",
 18       "st": "shanghai",
 19       "l": "shanghai",
 20       "o": "system:kube-controller-manager",
 21       "ou": "system"
 22     }
 23   ]
 24 }
 25 eof
 26 #创建kube-controller-manager的ca证书请求文件

解释：

hosts 列表包含所有 kube-controller-manager 节点 ip；

cn 和 o 均为 system:kube-controller-manager，kubernetes 内置的 clusterrolebindings system:kube-controller-manager 赋予 kube-controller-manager 工作所需的权限。

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# cfssl gencert -ca=/opt/k8s/work/ca.pem \
  3 -ca-key=/opt/k8s/work/ca-key.pem -config=/opt/k8s/work/ca-config.json \
  4 -profile=kubernetes kube-controller-manager-csr.json | cfssljson -bare kube-controller-manager	#生成ca密钥（ca-key.pem）和证书（ca.pem）

1.3 分发证书和私钥

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster01 work]# for master_ip in ${master_ips[@]}
  4   do
  5     echo ">>> ${master_ip}"
  6     scp kube-controller-manager*.pem root@${master_ip}:/etc/kubernetes/cert/
  7   done

1.4 创建和分发kubeconfig

kube-controller-manager 使用 kubeconfig 文件访问 apiserver，该文件提供了 apiserver 地址、嵌入的 ca 证书和 kube-controller-manager 证书：

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster01 work]# kubectl config set-cluster kubernetes \
  4   --certificate-authority=/opt/k8s/work/ca.pem \
  5   --embed-certs=true \
  6   --server=${kube_apiserver} \
  7   --kubeconfig=kube-controller-manager.kubeconfig
  8 
  9 [root@k8smaster01 work]# kubectl config set-credentials system:kube-controller-manager \
 10   --client-certificate=kube-controller-manager.pem \
 11   --client-key=kube-controller-manager-key.pem \
 12   --embed-certs=true \
 13   --kubeconfig=kube-controller-manager.kubeconfig
 14 
 15 [root@k8smaster01 work]# kubectl config set-context system:kube-controller-manager \
 16   --cluster=kubernetes \
 17   --user=system:kube-controller-manager \
 18   --kubeconfig=kube-controller-manager.kubeconfig
 19 
 20 [root@k8smaster01 work]# kubectl config use-context system:kube-controller-manager --kubeconfig=kube-controller-manager.kubeconfig
 21 
 22 [root@k8smaster01 ~]# cd /opt/k8s/work
 23 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
 24 [root@k8smaster01 work]# for master_ip in ${master_ips[@]}
 25   do
 26     echo ">>> ${master_ip}"
 27     scp kube-controller-manager.kubeconfig root@${master_ip}:/etc/kubernetes/
 28   done

1.5 创建kube-controller-manager的systemd

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster01 work]# cat > kube-controller-manager.service.template <<eof
  4 [unit]
  5 description=kubernetes controller manager
  6 documentation=https://github.com/googlecloudplatform/kubernetes
  7 
  8 [service]
  9 workingdirectory=${k8s_dir}/kube-controller-manager
 10 execstart=/opt/k8s/bin/kube-controller-manager \\
 11   --profiling \\
 12   --cluster-name=kubernetes \\
 13   --controllers=*,bootstrapsigner,tokencleaner \\
 14   --kube-api-qps=1000 \\
 15   --kube-api-burst=2000 \\
 16   --leader-elect \\
 17   --use-service-account-credentials\\
 18   --concurrent-service-syncs=2 \\
 19   --bind-address=##master_ip## \\
 20   --secure-port=10252 \\
 21   --tls-cert-file=/etc/kubernetes/cert/kube-controller-manager.pem \\
 22   --tls-private-key-file=/etc/kubernetes/cert/kube-controller-manager-key.pem \\
 23   --port=0 \\
 24   --authentication-kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \\
 25   --client-ca-file=/etc/kubernetes/cert/ca.pem \\
 26   --requestheader-allowed-names="" \\
 27   --requestheader-client-ca-file=/etc/kubernetes/cert/ca.pem \\
 28   --requestheader-extra-headers-prefix="x-remote-extra-" \\
 29   --requestheader-group-headers=x-remote-group \\
 30   --requestheader-username-headers=x-remote-user \\
 31   --authorization-kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \\
 32   --cluster-signing-cert-file=/etc/kubernetes/cert/ca.pem \\
 33   --cluster-signing-key-file=/etc/kubernetes/cert/ca-key.pem \\
 34   --experimental-cluster-signing-duration=8760h \\
 35   --horizontal-pod-autoscaler-sync-period=10s \\
 36   --concurrent-deployment-syncs=10 \\
 37   --concurrent-gc-syncs=30 \\
 38   --node-cidr-mask-size=24 \\
 39   --service-cluster-ip-range=${service_cidr} \\
 40   --pod-eviction-timeout=6m \\
 41   --terminated-pod-gc-threshold=10000 \\
 42   --root-ca-file=/etc/kubernetes/cert/ca.pem \\
 43   --service-account-private-key-file=/etc/kubernetes/cert/ca-key.pem \\
 44   --kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \\
 45   --logtostderr=true \\
 46   --v=2
 47 restart=on-failure
 48 restartsec=5
 49 
 50 [install]
 51 wantedby=multi-user.target
 52 eof

1.6 分发systemd

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster01 work]# for (( i=0; i < 3; i++ ))
  4   do
  5     sed -e "s/##master_name##/${master_names[i]}/" -e "s/##master_ip##/${master_ips[i]}/" kube-controller-manager.service.template > kube-controller-manager-${master_ips[i]}.service
  6   done						#修正相应ip
  7 [root@k8smaster01 work]# ls kube-controller-manager*.service
  8 [root@k8smaster01 ~]# cd /opt/k8s/work
  9 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
 10 [root@k8smaster01 work]# for master_ip in ${master_ips[@]}
 11   do
 12     echo ">>> ${master_ip}"
 13     scp kube-controller-manager-${master_ip}.service root@${master_ip}:/etc/systemd/system/kube-controller-manager.service
 14   done						#分发system

二 启动并验证

2.1 启动kube-controller-manager 服务

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster01 work]# for master_ip in ${master_ips[@]}
  4   do
  5     echo ">>> ${master_ip}"
  6     ssh root@${master_ip} "mkdir -p ${k8s_dir}/kube-controller-manager"
  7     ssh root@${master_ip} "systemctl daemon-reload && systemctl enable kube-controller-manager && systemctl restart kube-controller-manager"
  8   done

2.2 检查kube-controller-manager 服务

  1 [root@k8smaster01 ~]# source /opt/k8s/bin/environment.sh
  2 [root@k8smaster01 ~]# for master_ip in ${master_ips[@]}
  3   do
  4     echo ">>> ${master_ip}"
  5     ssh root@${master_ip} "systemctl status kube-controller-manager|grep active"
  6   done

2.3 查看输出的 metrics

  1 [root@k8smaster01 ~]# curl -s --cacert /opt/k8s/work/ca.pem --cert /opt/k8s/work/admin.pem --key /opt/k8s/work/admin-key.pem https://172.24.8.71:10252/metrics |head

注意：以上命令在 kube-controller-manager 节点上执行。

2.4 查看权限

  1 [root@k8smaster01 ~]# kubectl describe clusterrole system:kube-controller-manager

clusterole system:kube-controller-manager 的权限很小，只能创建 secret、serviceaccount 等资源对象，各 controller 的权限分散到 clusterrole system:controller:xxx 中。

当在 kube-controller-manager 的启动参数中添加 --use-service-account-credentials=true 参数，这样 main controller 会为各 controller 创建对应的 serviceaccount xxx-controller。内置的 clusterrolebinding system:controller:xxx 将赋予各 xxx-controller serviceaccount 对应的 clusterrole system:controller:xxx 权限。

  1 [root@k8smaster01 ~]# kubectl get clusterrole|grep controller

如deployment controller：

  1 [root@k8smaster01 ~]# kubectl describe clusterrole system:controller:deployment-controller

2.5 查看当前leader

  1 [root@k8smaster01 ~]# kubectl get endpoints kube-controller-manager --namespace=kube-system  -o yaml

kubelet 认证和授权：https://kubernetes.io/docs/admin/kubelet-authentication-authorization/#kubelet-authorization