部署高可用 schduler

目錄

• 創建 kube-scheduler 證書和私鑰
• 創建和分發 kubeconfig 文件
• 創建 kube-scheduler 配置文件
• 創建kube-scheduler啟動文件
• 啟動kube-scheduler
  • 檢查服務運行狀態
• 查看輸出的 metrics
• 查看當前leader
• 通過 apiserver 查看 schduler 狀態

創建 kube-scheduler 證書和私鑰

創建證書簽名請求：

cd /opt/k8s/work
cat > kube-scheduler-csr.json <<EOF
{
    "CN": "system:kube-scheduler",
    "hosts": [
        "127.0.0.1",
        "10.0.20.11",
        "10.0.20.12",
        "10.0.20.13",
        "node01.k8s.com",
        "node02.k8s.com",
        "node03.k8s.com"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
      {
        "C": "CN",
        "ST": "BeiJing",
        "L": "BeiJing",
        "O": "system:kube-scheduler",
        "OU": "4Paradigm"
      }
    ]
}
EOF

• hosts 列表包含所有 kube-scheduler 節點 IP；
• CN 和 O 均為 system:kube-scheduler，kubernetes 內置的 ClusterRoleBindings system:kube-scheduler 將賦予 kube-scheduler 工作所需的權限；

生成證書和私鑰：

cd /opt/k8s/work
cfssl gencert -ca=/opt/k8s/work/ca.pem \
  -ca-key=/opt/k8s/work/ca-key.pem \
  -config=/opt/k8s/work/ca-config.json \
  -profile=kubernetes kube-scheduler-csr.json | cfssljson -bare kube-scheduler
ls kube-scheduler*pem

將生成的證書和私鑰分發到所有 master 節點

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp kube-scheduler*.pem root@${node_ip}:/etc/kubernetes/cert/
  done

創建和分發 kubeconfig 文件

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
kubectl config set-cluster kubernetes \
  --certificate-authority=/opt/k8s/work/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=kube-scheduler.kubeconfig
kubectl config set-credentials system:kube-scheduler \
  --client-certificate=kube-scheduler.pem \
  --client-key=kube-scheduler-key.pem \
  --embed-certs=true \
  --kubeconfig=kube-scheduler.kubeconfig
kubectl config set-context system:kube-scheduler \
  --cluster=kubernetes \
  --user=system:kube-scheduler \
  --kubeconfig=kube-scheduler.kubeconfig
kubectl config use-context system:kube-scheduler --kubeconfig=kube-scheduler.kubeconfig

分發 kubeconfig 到所有 master 節點

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp kube-scheduler.kubeconfig root@${node_ip}:/etc/kubernetes/
  done

創建 kube-scheduler 配置文件

cd /opt/k8s/work
cat >kube-scheduler.yaml.template <<EOF
apiVersion: kubescheduler.config.k8s.io/v1alpha1
kind: KubeSchedulerConfiguration
bindTimeoutSeconds: 600
clientConnection:
  burst: 200
  kubeconfig: "/etc/kubernetes/kube-scheduler.kubeconfig"
  qps: 100
enableContentionProfiling: false
enableProfiling: true
hardPodAffinitySymmetricWeight: 1
healthzBindAddress: 127.0.0.1:10251
leaderElection:
  leaderElect: true
metricsBindAddress: ##NODE_IP##:10251
EOF

• –kubeconfig：指定 kubeconfig 文件路徑，kube-scheduler 使用它連接和驗證 kube-apiserver；
• –leader-elect=true：集群運行模式，啟用選舉功能；被選為 leader 的節點負責處理工作，其它節點為阻塞狀態；

替換模板文件中的變量：

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for (( i=0; i < 3; i++ ))
  do
    sed -e "s/##NODE_NAME##/${NODE_NAMES[i]}/" -e "s/##NODE_IP##/${NODE_IPS[i]}/" kube-scheduler.yaml.template > kube-scheduler-${NODE_IPS[i]}.yaml
  done
ls kube-scheduler*.yaml

分發 kube-scheduler 配置文件到所有 master 節點：

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp kube-scheduler-${node_ip}.yaml root@${node_ip}:/etc/kubernetes/kube-scheduler.yaml
  done

創建kube-scheduler啟動文件

創建啟動文件模板

cd /opt/k8s/work
cat > kube-scheduler.service.template <<EOF
[Unit]
Description=Kubernetes Scheduler
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
[Service]
WorkingDirectory=${K8S_DIR}/kube-scheduler
ExecStart=/opt/k8s/bin/kube-scheduler \\
  --config=/etc/kubernetes/kube-scheduler.yaml \\
  --bind-address=##NODE_IP## \\
  --secure-port=10259 \\
  --port=0 \\
  --tls-cert-file=/etc/kubernetes/cert/kube-scheduler.pem \\
  --tls-private-key-file=/etc/kubernetes/cert/kube-scheduler-key.pem \\
  --authentication-kubeconfig=/etc/kubernetes/kube-scheduler.kubeconfig \\
  --client-ca-file=/etc/kubernetes/cert/ca.pem \\
  --requestheader-allowed-names="" \\
  --requestheader-client-ca-file=/etc/kubernetes/cert/ca.pem \\
  --requestheader-extra-headers-prefix="X-Remote-Extra-" \\
  --requestheader-group-headers=X-Remote-Group \\
  --requestheader-username-headers=X-Remote-User \\
  --authorization-kubeconfig=/etc/kubernetes/kube-scheduler.kubeconfig \\
  --logtostderr=true \\
  --v=2
Restart=always
RestartSec=5
StartLimitInterval=0
[Install]
WantedBy=multi-user.target
EOF

替換模板文件中的變量：

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for (( i=0; i < 3; i++ ))
  do
    sed -e "s/##NODE_NAME##/${NODE_NAMES[i]}/" -e "s/##NODE_IP##/${NODE_IPS[i]}/" kube-scheduler.service.template > kube-scheduler-${NODE_IPS[i]}.service 
  done
ls kube-scheduler*.service

分發啟動文件至所有master節點

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp kube-scheduler-${node_ip}.service root@${node_ip}:/etc/systemd/system/kube-scheduler.service
  done

啟動kube-scheduler

source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "mkdir -p ${K8S_DIR}/kube-scheduler"
    ssh root@${node_ip} "systemctl daemon-reload && systemctl enable kube-scheduler && systemctl restart kube-scheduler"
done

檢查服務運行狀態

source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "systemctl status kube-scheduler|grep Active"
  done

查看輸出的 metrics

注意：以下命令在 kube-scheduler 節點上執行。

• kube-scheduler 監聽 10251 和 10259 端口：
• 10251：接收 http 請求，非安全端口，不需要認證授權；
• 10259：接收 https 請求，安全端口，需要認證授權；
• 兩個接口都對外提供 /metrics 和 /healthz 的訪問。

[root@node01 work]# curl -s http://10.0.20.11:10251/metrics|head
# HELP apiserver_audit_event_total Counter of audit events generated and sent to the audit backend.
# TYPE apiserver_audit_event_total counter
apiserver_audit_event_total 0
# HELP apiserver_audit_requests_rejected_total Counter of apiserver requests rejected due to an error in audit logging backend.
# TYPE apiserver_audit_requests_rejected_total counter
apiserver_audit_requests_rejected_total 0
# HELP apiserver_client_certificate_expiration_seconds Distribution of the remaining lifetime on the certificate used to authenticate a request.
# TYPE apiserver_client_certificate_expiration_seconds histogram
apiserver_client_certificate_expiration_seconds_bucket{le="0"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="1800"} 0

查看當前leader

[root@node01 work]# kubectl get endpoints kube-scheduler --namespace=kube-system  -o yaml
apiVersion: v1
kind: Endpoints
metadata:
  annotations:
    control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"node01.k8s.com_e83f3d5c-dcbe-48ad-aaa8-e1fcd2279573","leaseDurationSeconds":15,"acquireTime":"2019-12-05T08:41:51Z","renewTime":"2019-12-05T08:43:04Z","leaderTransitions":0}'
  creationTimestamp: "2019-12-05T08:41:51Z"
  name: kube-scheduler
  namespace: kube-system
  resourceVersion: "3144"
  selfLink: /api/v1/namespaces/kube-system/endpoints/kube-scheduler
  uid: 509afbcd-4369-4f44-a44a-e4d3fe84c31f

通過 apiserver 查看 schduler 狀態

[root@node01 work]# kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
scheduler            Healthy   ok                  
controller-manager   Healthy   ok                  
etcd-2               Healthy   {"health":"true"}   
etcd-1               Healthy   {"health":"true"}   
etcd-0               Healthy   {"health":"true"}

這里看到 schduler 的狀態已經是 ok 了，在 測試訪問apiserver狀態