kubernetes之配置MetricsServer
Kubernetes 1.8 关于资源使⽤情况的 metrics，可以通过 Metrics API 获取到， Kubernetes 1.11 已经废弃 heapster。这⾥我们基于 Kubernetes 1.14.1 版本安装 Metrics Server。⾸先，先说明下集环境：
[root@node-01]# kubectl get nodes
NAME      STATUS  ROLES    AGE    VERSION
node-01  Ready    master  2d1h  v1.14.1
node-02  Ready    master  2d1h  v1.14.1
node-03  Ready    master  2d1h  v1.14.1
node-04  Ready    <none>  2d1h  v1.14.1
node-05  Ready    <none>  2d1h  v1.14.1
node-06  Ready    <none>  2d1h  v1.14.1
当整个集部署完成后，kubectl top 命令不会返回任何内容，因为 Heapster 和metrics-server都没有安装，但是⾃ Kubernetes 1.11版本后 heapster已经被废弃了，取⽽代之的是更丰富的 metrics-server。
配置 /etc/kubernetes/manifests/kube-controller-manager.yaml
--horizontal-pod-autoscaler-use-rest-clients=true
kubedam 创建的集，修改配置⽂件后会⾃动加载。如果⼿动创建的集，需要重启kube-controller-manager服务。
准备部署 Metrics Server 的 yaml⽂件
[root@node-01]# git clone github/kubernetes-incubator/metrics-server
下载完成后还需要对 metrics-server/deploy/1.8+/resource-reader.yaml⽂件进⾏修改，需要修改的内容如下：
[root@node-011.8+]# cat resource-reader.yaml
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: system:metrics-server
rules:
- apiGroups:
- ""
resources:
- pods
- nodes
- namespaces      # 增加此⾏
-
nodes/stats
verbs:
- get
- list
- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: system:metrics-server
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:metrics-server
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
修改 metrics-server/deploy/1.8+/metrics-server-deployment.yaml⽂件：
[root@node-011.8+]# cat 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: io/metrics-server-amd64:v0.3.2
command:
- /metrics-server
- --kubelet-insecure-tls
-
--kubelet-preferred-address-types=InternalIP  # 如果不配置此项，会报错不到node
imagePullPolicy: Always
volumeMounts:
- name: tmp-dir
mountPath: /tmp
上⾯如果报错是因为 node-01 和 node-02 是⼀个独⽴的 Kubernetes 演⽰环境，只是修改了这两个节点系统的 /etc/hosts⽂件，⽽并没有内⽹的 DNS 服务器，所以 metrics-server 中不认识 node-01 和 node-02 的名字。
修改完成就可以正式部署了：
[root@node-011.8+]# kubectl apply -f .
clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created
clusterrolebinding.rbac.authorization.k8s.io/metrics-server:system:auth-delegator created
rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created
apiservice.apiregistration.k8s.ics.k8s.io created
serviceaccount/metrics-server created
service/metrics-server created
clusterrole.rbac.authorization.k8s.io/system:metrics-server created
clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server created
Metrics Server 相关 pod 、service 默认部署在 kube-system的 NAMESPACE 下：
[root@node-011.8+]# kubectl get pods -n kube-system | grep metrics
metrics-server-5845cc8fd4-kkq6b        1/1    Running  0          18m
[root@node-011.8+]# kubectl get svc -n kube-system | grep metrics
metrics-server            ClusterIP  10.245.141.103  <none>        443/TCP                  20m
部署完成后使⽤如下命令查看node相关指标，需要等30s左右的时间：
[root@node-011.8+]# kubectl get --raw "/apis/metrics.k8s.io/v1beta1/nodes"
{"kind":"NodeMetricsList","apiVersion":"metrics.k8s.io/v1beta1","metadata":{"selfLink":"/apis/metrics.k8s.io/v1beta1/nodes"},"items":[
{"metadata":{"name":"node-02","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-02","creationTimestamp":"2019-05-08T08:17:11Z"},"timestamp":"2019-05-08T08:17:01Z","window":"30s","usage":{"cpu":"221367011n","memory":" {"metadata":{"name":"node-03","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-03","creationTimestamp":"2019-05-08T08:17:11Z"},"timestamp":"2019-05-08T08:17:08Z","window":"30s","usage":{"cpu":"198021879n","memory":" {"metadata":{"name":"node-04","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-04","creationTimestamp":"2019-05-08T08:17:11Z"},"timestamp":"2019-05-08T08:17:03Z","window":"30s","usage":{"cpu":"55570780n","memory":"719012Ki {"metadata":{"name":"node-05","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-05","creationTimestamp":"2019-05-08T08:17:1
1Z"},"timestamp":"2019-05-08T08:17:01Z","window":"30s","usage":{"cpu":"60116633n","memory":"851180Ki {"metadata":{"name":"node-06","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-06","creationTimestamp":"2019-05-08T08:17:11Z"},"timestamp":"2019-05-08T08:16:59Z","window":"30s","usage":{"cpu":"51157291n","memory":"677532Ki {"metadata":{"name":"node-01","selfLink":"/apis/metrics.k8s.io/v1beta1/nodes/node-01","creationTimestamp":"2019-05-08T08:17:11Z"},"timestamp":"2019-05-08T08:17:02Z","window":"30s","usage":{"cpu":"263183209n","memory":" Metrics API
Metrics Server 从 Kubernetes 集中每个 Node 上 kubelet 的 API 收集 metrics 数据。通过 Metrics API 可以获取Kubernetes 资源的 Metrics 指标，Metrics API 挂载/apis/metrics.
下。可以使⽤kubectl top命令访问 Metrics API，例如:
[root@node-01 ~]# kubectl top pods
NAME                                CPU(cores)  MEMORY(bytes)
my-nginx-6785b88976-7rrll          0m          1Mi
nginx-deployment-6d6fdc59f7-pfcfj  1m          1Mi
nginx-deployment-6d6fdc59f7-vcclz  1m          1Mi
[root@node-01 ~]# kubectl top nodes
NAME      CPU(cores)  CPU%  MEMORY(bytes)  MEMORY%
node-01  276m        6%    2403Mi          31%
node-02  245m        6%    1868Mi          24%
node-03  206m        5%    1766Mi          22%
node-04  74m          1%    703Mi          9%
node-05  77m          1%    832Mi          10%
node-06  56m          1%    661Mi          8%
⾄此，Kubernetes 集中的 Metrics Server 就配置完成了。但是在dashboard中看不到内存和CPU信息，⽽如果使⽤heapster则能看到。
所有yaml⽂件如下
# cat aggregated-metrics-reader.yaml
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: system:aggregated-metrics-reader
labels:
rbac.authorization.k8s.io/aggregate-to-view: "true"
rbac.authorization.k8s.io/aggregate-to-edit: "true"
rbac.authorization.k8s.io/aggregate-to-admin: "true"
rules:
-
apiGroups: ["metrics.k8s.io"]
resources: ["pods"]
verbs: ["get", "list", "watch”]
# cat auth-delegator.yaml
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: metrics-server:system:auth-delegator
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:auth-delegator
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
# cat auth-reader.yaml
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
name: metrics-server-auth-reader
namespace: kube-system
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
—————
# cat metrics-apiservice.yaml
---
apiVersion: apiregistration.k8s.io/v1beta1
kind: APIService
metadata:
name: ics.k8s.io
spec:
service:
name: metrics-server
namespace: kube-system
group: metrics.k8s.io
version: v1beta1
insecureSkipTLSVerify: true
groupPriorityMinimum: 100
versionPriority: 100
# cat metrics-server-deployment.yaml
---
apiVersion: v1
nodeselectorkind: 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: io/metrics-server-amd64:v0.3.2
command:
- /metrics-server
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
imagePullPolicy: Always
volumeMounts:
- name: tmp-dir
mountPath: /tmp
# cat metrics-server-service.yaml
---
apiVersion: v1
kind: Service
metadata:
name: metrics-server
namespace: kube-system
labels:
kubernetes.io/name: "Metrics-server"
kubernetes.io/cluster-service: "true"
spec:
selector:
k8s-app: metrics-server
ports:
- port: 443
protocol: TCP
targetPort: 443
# cat resource-reader.yaml
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: system:metrics-server
rules:
- apiGroups:
- ""
resources:
- pods
- nodes
- namespaces      # 增加此⾏
- nodes/stats
verbs:
- get
-
list
- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: system:metrics-server
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:metrics-server
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system

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