Metrics-server插件安装配置

1、创建 metrics-server 使用的证书

vim metrics-server-csr.json

{
  "CN": "aggregator",
  "hosts": [],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "k8s",
      "OU": "System"
    }
  ]
}

cfssl gencert -ca=/etc/kubernetes/ssl/ca.pem \
              -ca-key=/etc/kubernetes/ssl/ca-key.pem \ 
              -config=/opt/ssl/config.json \
              -profile=kubernetes metrics-server-csr.json | cfssljson -bare metrics-server

将生成的证书拷贝到所有node和master节点
cp metrics-server*.pem /etc/kubernetess/ssl/
scp metrics-server*.pem 192.168.1.8:/etc/kubernetess/ssl/

2、修改 kubernetes 控制平面组件的配置以支持 metrics-server

kube-apiserver

添加如下配置参数：

  --requestheader-client-ca-file=/etc/kubernetes/ssl/ca.pem \
  --requestheader-extra-headers-prefix=X-Remote-Extra- \
  --requestheader-group-headers=X-Remote-Group \
  --requestheader-username-headers=X-Remote-User \
  --proxy-client-cert-file=/etc/kubernetes/ssl/metrics-server.pem \
  --proxy-client-key-file=/etc/kubernetes/ssl/metrics-server-key.pem \
  --runtime-config=api/all=true \

--requestheader-XXX、--proxy-client-XXX 是 kube-apiserver 的 aggregator layer 相关的配置参数，metrics-server & HPA 需要使用；
--requestheader-client-ca-file：用于签名 --proxy-client-cert-file 和 --proxy-client-key-file 指定的证书；在启用了 metric aggregator 时使用；
如果 kube-apiserver 机器没有运行 kube-proxy，则还需要添加 --enable-aggregator-routing=true 参数

注意：requestheader-client-ca-file 指定的 CA 证书，必须具有 client auth and server auth

kube-controller-manager

添加如下配置参数：

--horizontal-pod-autoscaler-use-rest-clients=true

用于配置 HPA 控制器使用 REST 客户端获取 metrics 数据

3、修改插件配置文件

# git clone https://github.com/kubernetes-incubator/metrics-server

# cd metrics-server/deploy/1.8+

# vim metrics-server-deployment.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: metrics-server
  namespace: kube-system
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: metrics-server
  namespace: kube-system
  labels:
    k8s-app: metrics-server
spec:
  selector:
    matchLabels:
      k8s-app: metrics-server
  template:
    metadata:
      name: metrics-server
      labels:
        k8s-app: metrics-server
    spec:
      serviceAccountName: metrics-server
      volumes:
      # mount in tmp so we can safely use from-scratch images and/or read-only containers
      - name: tmp-dir
        emptyDir: {}
      containers:
      - name: metrics-server
        image: anjia0532/google-containers.metrics-server-amd64:v0.3.1
        imagePullPolicy: Always
        command:
        - /metrics-server
        - --kubelet-insecure-tls
        - --kubelet-preferred-address-types=InternalIP
        volumeMounts:
        - name: tmp-dir
          mountPath: /tmp

注释：1、metrics默认使用hostname来通信的，而且coredns中已经添加了宿主机的/etc/resolv.conf，
所以只需要添加一个内部的dns服务器或者在pod的deployment的yaml手动添加主机解析记录,再或者改变参数为InternalIP，直接用ip来连接
2、kubelet-insecure-tls: 跳过验证kubelet的ca证书，暂时开启。（不推荐用于生产环境）

4、修改完成之后开始部署

# kubectl apply .

# kubectl get pods -n kube-system | grep metrics

# kubectl get apiservice v1beta1.metrics.k8s.io -o yaml

5、验证是否成功

# kubectl top nodes

NAME    CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
es-60   377m         18%    5915Mi          76%       
es-61   267m         13%    5479Mi          70%

参考资料： https://github.com/kubernetes-incubator/metrics-server/issues/97

Metrics-server插件安装配置

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