011.Kubernetes二进制部署kube-scheduler

一 部署高可用kube-scheduler

1.1 高可用kube-scheduler介绍

本实验部署一个三实例 kube-scheduler 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，10251) 输出 prometheus 格式的 metrics。

1.2 创建kube-scheduler证书和私钥

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# cat > kube-scheduler-csr.json <<EOF
  3 {
  4   "CN": "system:kube-scheduler",
  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-scheduler",
 21       "OU": "System"
 22     }
 23   ]
 24 }
 25 EOF
 26 #创建kube-scheduler的CA证书请求文件

解释：

hosts 列表包含所有 kube-scheduler 节点 IP；

CN 和 O 均为 system:kube-scheduler，kubernetes 内置的 ClusterRoleBindings system:kube-scheduler 将赋予 kube-scheduler 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-scheduler-csr.json | cfssljson -bare kube-scheduler	#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 ">>> ${master_ip}"
  6     scp kube-scheduler*.pem root@${master_ip}:/etc/kubernetes/cert/
  7   done

1.4 创建和分发kubeconfig

kube-scheduler 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-scheduler 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-scheduler.kubeconfig
  8
  9 [root@k8smaster01 work]# kubectl config set-credentials system:kube-scheduler \
 10   --client-certificate=kube-scheduler.pem \
 11   --client-key=kube-scheduler-key.pem \
 12   --embed-certs=true \
 13   --kubeconfig=kube-scheduler.kubeconfig
 14
 15 [root@k8smaster01 work]# kubectl config set-context system:kube-scheduler \
 16   --cluster=kubernetes \
 17   --user=system:kube-scheduler \
 18   --kubeconfig=kube-scheduler.kubeconfig
 19
 20 [root@k8smaster01 work]# kubectl config use-context system:kube-scheduler --kubeconfig=kube-scheduler.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 ">>> ${master_ip}"
 27     scp kube-scheduler.kubeconfig root@${master_ip}:/etc/kubernetes/
 28   done

1.5 创建kube-scheduler 配置文件

  1 [root@k8smaster01 ~]# cd /opt/k8s/work
  2 [root@k8smaster01 work]# cat >kube-scheduler.yaml.template <<EOF
  3 apiVersion: kubescheduler.config.k8s.io/v1alpha1
  4 kind: KubeSchedulerConfiguration
  5 bindTimeoutSeconds: 600
  6 clientConnection:
  7   burst: 200
  8   kubeconfig: "/etc/kubernetes/kube-scheduler.kubeconfig"
  9   qps: 100
 10 enableContentionProfiling: false
 11 enableProfiling: true
 12 hardPodAffinitySymmetricWeight: 1
 13 healthzBindAddress: ##MASTER_IP##:10251
 14 leaderElection:
 15   leaderElect: true
 16 metricsBindAddress: ##MASTER_IP##:10251
 17 EOF

解释：

--kubeconfig：指定 kubeconfig 文件路径，kube-scheduler 使用它连接和验证 kube-apiserver；

--leader-elect=true：集群运行模式，启用选举功能；被选为 leader 的节点负责处理工作，其它节点为阻塞状态。

  1 [root@k8smaster ~]# cd /opt/k8s/work
  2 [root@k8smaster work]# source /opt/k8s/bin/environment.sh
  3 [root@k8smaster 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-scheduler.yaml.template > kube-scheduler-${MASTER_IPS[i]}.yaml
  6   done					#替换模板文件中的变量
  7 [root@k8smaster01 work]# ls kube-scheduler*.yaml
  8 #MASTER_NAMES 和 MASTER_IPS 为相同长度的 bash 数组，分别为节点名称和对应的 IP

1.6 分发配置文件

  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 ">>> ${master_ip}"
  6     scp kube-scheduler-${master_ip}.yaml root@${master_ip}:/etc/kubernetes/kube-scheduler.yaml
  7   done

1.7 创建kube-scheduler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-scheduler.service.template <<EOF
  4 [Unit]
  5 Description=Kubernetes Scheduler
  6 Documentation=https://github.com/GoogleCloudPlatform/kubernetes
  7
  8 [Service]
  9 WorkingDirectory=${K8S_DIR}/kube-scheduler
 10 ExecStart=/opt/k8s/bin/kube-scheduler \\
 11   --config=/etc/kubernetes/kube-scheduler.yaml \\
 12   --bind-address=##MASTER_IP## \\
 13   --secure-port=10259 \\
 14   --port=0 \\
 15   --tls-cert-file=/etc/kubernetes/cert/kube-scheduler.pem \\
 16   --tls-private-key-file=/etc/kubernetes/cert/kube-scheduler-key.pem \\
 17   --authentication-kubeconfig=/etc/kubernetes/kube-scheduler.kubeconfig \\
 18   --client-ca-file=/etc/kubernetes/cert/ca.pem \\
 19   --requestheader-allowed-names="" \\
 20   --requestheader-client-ca-file=/etc/kubernetes/cert/ca.pem \\
 21   --requestheader-extra-headers-prefix="X-Remote-Extra-" \\
 22   --requestheader-group-headers=X-Remote-Group \\
 23   --requestheader-username-headers=X-Remote-User \\
 24   --authorization-kubeconfig=/etc/kubernetes/kube-scheduler.kubeconfig \\
 25   --logtostderr=true \\
 26   --v=2
 27 Restart=always
 28 RestartSec=5
 29 StartLimitInterval=0
 30
 31 [Install]
 32 WantedBy=multi-user.target
 33 EOF

1.8 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-scheduler.service.template > kube-scheduler-${MASTER_IPS[i]}.service
  6   done					#修正相应IP
  7 [root@k8smaster01 work]# ls kube-scheduler*.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 ">>> ${master_ip}"
 13     scp kube-scheduler-${master_ip}.service root@${master_ip}:/etc/systemd/system/kube-scheduler.service
 14   done						#分发system

二 启动并验证

2.1 启动kube-scheduler 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 ${K8S_DIR}/kube-scheduler"
  7     ssh root@${master_ip} "systemctl daemon-reload && systemctl enable kube-scheduler && systemctl restart kube-scheduler"
  8   done						#启动服务前必须先创建工作目录

2.2 检查kube-scheduler 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-scheduler|grep Active"
  6   done

2.3 查看输出的 metrics

kube-scheduler 监听 10251 和 10251 端口：

• 10251：接收 http 请求，非安全端口，不需要认证授权；
• 10259：接收 https 请求，安全端口，需要认证授权。
• 两个接口都对外提供 /metrics 和 /healthz 的访问。

  1 [root@k8smaster01 ~]# sudo netstat -lnpt |grep kube-sch

  1 [root@k8smaster01 ~]# curl -s http://127.0.0.1:10251/metrics |head
  2 [root@k8smaster01 ~]# curl -s --cacert /opt/k8s/work/ca.pem --cert /opt/k8s/work/admin.pem --key /opt/k8s/work/admin-key.pem https://172.24.8.71:10259/metrics |head

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

2.4 查看当前leader

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

当前leader为k8smaster01。