010.Kubernetes binary deployment kube-controller-manager

Keywords: Linux Kubernetes JSON ssh kubelet

1. Deploy highly available kube-controller-manager

1.1 Introduction to highly available kube-controller-manager

In this experiment, a Three-instance cluster of kube-controller-manager is deployed. After starting, a leader node will be generated through the competitive election mechanism, and the other nodes will be blocked.When the leader node is unavailable, the blocked node will elect a new leader node again to ensure service availability.
To ensure communication security, this document generates an x509 certificate and a private key, which is used by kube-controller-manager in two cases:
  • Communicate with the secure port of kube-apiserver;
  • Output prometheus metrics on secure port (https, 10252).

1.2 Create a kube-controller-manager certificate and private key

  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 #Create CA Certificate Request File for kube-controller-manager
Explanation:
The hosts list contains all the kube-controller-manager node IP;
Both CN and O are system:kube-controller-manager, and the built-in ClusterRoleBindings system:kube-controller-manager of kubernetes grants kube-controller-manager the privileges required to function.

  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	#Generate CA key (ca-key.pem) and certificate (ca.pem)

1.3 Distributing certificates and private keys

  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 Create and distribute kubeconfig

Kube-controller-manager accesses apiserver using a kubeconfig file that provides the apiserver address, embedded CA certificate, and kube-controller-manager certificate:
  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 Create systemd for kube-controller-manager

  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 Distributing 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						#Correct corresponding 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						#Distribution system

2. Start and Verify

2.1 Start the kube-controller-manager service

  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 Check the kube-controller-manager service

  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 View metrics of output

  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
Note: The above command is executed on the kube-controller-manager node.

2.4 View Permissions

  1 [root@k8smaster01 ~]# kubectl describe clusterrole system:kube-controller-manager
ClusterRole system:kube-controller-manager has very small permissions and can only create resource objects such as secret, service account, etc. The permissions of each controller are distributed to ClusterRole system:controller:XXX.
When the--use-service-account-credentials=true parameter is added to the start parameter of the kube-controller-manager, the main controller creates the corresponding ServiceAccount XXX-controller for each controller.The built-in ClusterRoleBinding system:controller:XXX grants ClusterRole system:controller:XXX permissions to each XXX-controller ServiceAccount.
  1 [root@k8smaster01 ~]# kubectl get clusterrole|grep controller
For example, deployment controller:
  1 [root@k8smaster01 ~]# kubectl describe clusterrole system:controller:deployment-controller

2.5 View the current leader

  1 [root@k8smaster01 ~]# kubectl get endpoints kube-controller-manager --namespace=kube-system  -o yaml
Kubelet authentication and authorization: https://kubernetes.io/docs/admin/kubelet-authentication-authorization/#kubelet-authorization

Posted by 00Sven on Sat, 16 Nov 2019 21:55:10 -0800