【云原生】kubernetes v1.18部署Metrics-Server:v0.3.6

一、概述

介绍 Metrics Server 前首先介绍一下 Heapster，该工具是用于 Kubernetes 集群监控和性能分析工具，可以收集节点上的指标数据，例如，节点的 CPU、Memory、Network 和 Disk 的 Metric 数据。不过在 Kubernetes V1.11 版本后将被逐渐废弃。而 Metrics Server 正是 Heapster 的代替者。

Metrics Server 是 Kubernetes 集群核心监控数据的聚合器，Metrics Server 从 Kubelet 收集资源指标，并通过 Merics API 在 Kubernetes APIServer 中提供给缩放资源对象 HPA 使用。也可以通过 Metrics API 提供的 Kubectl top 查看 Pod 资源占用情况，从而实现对资源的自动缩放。

需要注意的是：

1. metric-server提供的是实时的指标（实际是最近一次采集的数据，保存在内存中），并没有数据库来存储；
2. 这些数据指标并非由metric-server本身采集，而是由每个节点上的cadvisor采集，metric-server只是发请求给cadvisor并将metric格式的数据转换成aggregate api；
3. 由于需要通过aggregate api来提供接口，需要集群中的kube-apiserver开启该功能

二、部署metrics-server

1. 创建components.yaml文件，将内容复制进去vim components.yaml

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:name: system:aggregated-metrics-readerlabels: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.iokind: ClusterRolename: system:auth-delegator
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:name: metrics-server-auth-readernamespace: kube-system
roleRef:apiGroup: rbac.authorization.k8s.iokind: Rolename: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system
---
apiVersion: apiregistration.k8s.io/v1beta1
kind: APIService
metadata:name: v1beta1.metrics.k8s.io
spec:service:name: metrics-servernamespace: kube-systemgroup: metrics.k8s.ioversion: v1beta1insecureSkipTLSVerify: truegroupPriorityMinimum: 100versionPriority: 100
---
apiVersion: v1
kind: ServiceAccount
metadata:name: metrics-servernamespace: kube-system
---
apiVersion: apps/v1
kind: Deployment
metadata:name: metrics-servernamespace: kube-systemlabels:k8s-app: metrics-server
spec:selector:matchLabels:k8s-app: metrics-servertemplate:metadata:name: metrics-serverlabels:k8s-app: metrics-serverspec:serviceAccountName: metrics-servervolumes:# mount in tmp so we can safely use from-scratch images and/or read-only containers- name: tmp-diremptyDir: {}containers:- name: metrics-serverimage: mirrorgooglecontainers/metrics-server-amd64:v0.3.6imagePullPolicy: IfNotPresentcommand:- /metrics-server- --kubelet-preferred-address-types=InternalIP- --kubelet-insecure-tls- --v=2args:- --cert-dir=/tmp- --secure-port=4443ports:- name: main-portcontainerPort: 4443protocol: TCPsecurityContext:readOnlyRootFilesystem: truerunAsNonRoot: truerunAsUser: 1000volumeMounts:- name: tmp-dirmountPath: /tmpnodeSelector:kubernetes.io/os: linuxkubernetes.io/arch: "amd64"
---
apiVersion: v1
kind: Service
metadata:name: metrics-servernamespace: kube-systemlabels:kubernetes.io/name: "Metrics-server"kubernetes.io/cluster-service: "true"
spec:selector:k8s-app: metrics-serverports:- port: 443protocol: TCPtargetPort: main-port
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:name: system:metrics-server
rules:
- apiGroups:- ""resources:- pods- nodes- nodes/stats- namespaces- configmapsverbs:- get- list- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:name: system:metrics-server
roleRef:apiGroup: rbac.authorization.k8s.iokind: ClusterRolename: system:metrics-server
subjects:
- kind: ServiceAccountname: metrics-servernamespace: kube-system

网上有很多是通过从github上下载yaml文件内容，然后进行更改的，但是实际执行起来就会出现这样那样的问题，要不是镜像拉不下来，要不各种报错，这个yaml文件内容已经是经过修改的，可以直接执行，即可成功。

2. 执行components.yaml

kubectl apply -f components.yaml

3. 验证Metrics Server组件部署成功

• 查看原生apiserver是否有metrics.k8s.io/v1beta1

[root@k8s-master1 ~]# kubectl api-versions|grep metrics
metrics.k8s.io/v1beta1

可以看到metrics.k8s.io/v1beta1群组已经注册到原生apiserver上。

• 查看metrics server pod是否运行正常

[root@k8s-master1 ~]# kubectl get pods -n kube-system |grep metrics
metrics-server-5dfbdf76fd-hrjdl       1/1     Running   1          12h

可以看到对应pod已经正常运行，接着查看pod日志kubectl logs -f pod/[pod名称] -n kube-system，只要metrics server pod没有出现错误日志，或者无法注册等信息，就表示pod里的容器运行正常。

• 使用kubectl top 命令查看pod的cpu ，内存占比，看看对应命令是否可以正常执行。

[root@k8s-master1 ~]# kubectl top nodes
NAME          CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%
k8s-master1   295m         7%     866Mi           11%
k8s-master2   273m         6%     1147Mi          14%
k8s-master3   233m         5%     669Mi           8%
k8s-node1     92m          2%     483Mi           6%