#什么是metrics-server？
kubernetes 集群资源监控之前可以通过 heapster 来获取数据，在 1.11 开始开始逐渐废弃 heapster 了，采用 metrics-server 来代替，metrics-server 是集群的核心监控数据的聚合器，它从 kubelet 公开的 Summary API 中采集指标信息，metrics-server 是扩展的 APIServer，依赖于kube-aggregator，因为我们需要在 APIServer 中开启相关参数。
查看 APIServer 参数配置，确保你的 APIServer 启动参数中包含下的一些参数配置。
...
- --requestheader-client-ca-file=/etc/kubernetes/certs/proxy-ca.crt
- --proxy-client-cert-file=/etc/kubernetes/certs/proxy.crt
- --proxy-client-key-file=/etc/kubernetes/certs/proxy.key
- --requestheader-allowed-names=aggregator
- --requestheader-extra-headers-prefix=X-Remote-Extra-
- --requestheader-group-headers=X-Remote-Group
- --requestheader-username-headers=X-Remote-User
- --enable-aggregator-routing=true
...
如果您未在 master 节点上运行 kube-proxy，则必须确保 kube-apiserver 启动参数中包含--enable-aggregator-routing=true
#安装
从Metrics Server版本下载最新版本，并按如下所示进行部署：
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.7/components.yaml
目前我采用最新版本部署，v0.3.7
#完整的资源清单文件
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
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", "nodes"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
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
---
apiVersion: rbac.authorization.k8s.io/v1
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
---
apiVersion: apiregistration.k8s.io/v1beta1
kind: APIService
metadata:
name: v1beta1.metrics.k8s.io
spec:
service:
name: metrics-server
namespace: kube-system
group: metrics.k8s.io
version: v1beta1
insecureSkipTLSVerify: true
groupPriorityMinimum: 100
versionPriority: 100
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: metrics-server
namespace: kube-system
---
apiVersion: apps/v1
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: coll/metrics-server:v0.3.7 # image默认是谷歌，修改为可用的
imagePullPolicy: IfNotPresent
args:
- --cert-dir=/tmp
- --secure-port=4443
command: #新增command配置
- /metrics-server
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
ports:
- name: main-port
containerPort: 4443
protocol: TCP
securityContext:
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
volumeMounts:
- name: tmp-dir
mountPath: /tmp
nodeSelector:
kubernetes.io/os: linux
---
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: main-port
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: system:metrics-server
rules:
- apiGroups:
- ""
resources:
- pods
- nodes
- nodes/stats
- namespaces
- configmaps
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
#遇到的问题
E0908 03:43:06.048002 1 reststorage.go:135] unable to fetch node metrics for node "build-02": no metrics known for node
E0908 03:43:06.048022 1 reststorage.go:135] unable to fetch node metrics for node "build-01": no metrics known for node
E0908 03:43:06.048030 1 reststorage.go:135] unable to fetch node metrics for node "build-03": no metrics known for node
E0908 03:43:48.828393 1 manager.go:111] unable to fully collect metrics: [unable to fully scrape metrics from source kubelet_summary:build-03: unable to fetch metrics from Kubelet build-03 (build-03): Get https://build-03:10250/stats/summary?only_cpu_and_memory=true: dial tcp: lookup build-03 on 10.96.0.10:53: server misbehaving, unable to fully scrape metrics from source kubelet_summary:build-01: unable to fetch metrics from Kubelet build-01 (build-01): Get https://build-01:10250/stats/summary?only_cpu_and_memory=true: dial tcp: lookup build-01 on 10.96.0.10:53: server misbehaving, unable to fully scrape metrics from source kubelet_summary:build-02: unable to fetch metrics from Kubelet build-02 (build-02): Get https://build-02:10250/stats/summary?only_cpu_and_memory=true: dial tcp: lookup build-02 on 10.96.0.10:53: server misbehaving]
因为部署集群的时候，CA 证书并没有把各个节点的 IP 签上去，所以这里 metrics-server 通过 IP 去请求时，提示签的证书没有对应的 IP（错误：x509: cannot validate certificate for 192.168.33.11 because it doesn’t contain any IP SANs），我们可以添加一个--kubelet-insecure-tls参数跳过证书校验：
command: #新增command配置
- /metrics-server
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
添加上面以上参数，然后再重新安装。
kubectl apply -f components.yaml
过一会可以看到，使用Metrics-Server收集到节点信息，说明Metrics-Server安装成功。
[root@build-01 manifests]# kubectl top node
NAME CPU(cores) CPU% MEMORY(bytes) MEMORY%
build-01 142m 3% 3818Mi 50%
build-02 83m 2% 3674Mi 48%
build-03 2782m 69% 4262Mi 55%
相关文档：
https://github.com/kubernetes-sigs/metrics-server
https://www.qikqiak.com/post/install-metrics-server/