Kubernetes系列之Kubernetes部署metrics-server

4、Kubernetes系列之Kubernetes部署metrics-server
#1、metrics-server簡介
自kubernetes 1.8開始，資源使用指標（如容器 CPU 和內存使用率）經過 Metrics API 在 Kubernetes 中獲取，metrics-server 替代了heapster。Metrics Server 實現了Resource Metrics API，Metrics Server 是集羣範圍資源使用數據的聚合器。 
Metrics Server 從每一個節點上的 Kubelet 公開的 Summary API 中採集指標信息。

Kubernetes中有些組件依賴資源指標API(metric API)的功能 ，如kubectl top 、hpa。若是沒有資源指標API接口，這些組件沒法運行。在以前使用的是Heapster，Heapster廢棄後改用metrics-server。

• 經過Metrics API能夠獲取指定node或者pod的當前資源使用狀況（而沒法獲取歷史數據）
• Metrics API的api路徑：/apis/metrics.k8s.io/
• Metrics API的使用須要在K8S集羣中成功部署metrics server

kubernetes metrics server 參考文檔 https://github.com/kubernetes-incubator/metrics-server

#2、安裝metrics-server

一、下載所需文件
# mkdir ./metrics-server  
# cd metrics-server/  
# for file in aggregated-metrics-reader.yaml auth-delegator.yaml auth-reader.yaml metrics-apiservice.yaml metrics-server-deployment.yaml metrics-server-service.yaml resource-reader.yaml; do  wget https://raw.githubusercontent.com/kubernetes-incubator/metrics-server/master/deploy/1.8%2B/$file;done 

二、這裏須要改2個地方，一個是鏡像的問題，一個是服務啓動的問題。  

# 在全部Node節點上執行。先把鏡像國通阿里雲的鏡像源下載下來。再改個名字。  
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/metrics-server-amd64:v0.3.3  
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/metrics-server-amd64:v0.3.3 k8s.gcr.io/metrics-server-amd64:v0.3.3  

# 修改metrics-server-deployment.yaml，增長一個imagePullPolicy，增長command內容，不然會報錯no metrics known for node。相關問題緣由自行百度。  
# vim metrics-server-deployment.yaml  
 30       containers:  
 31       - name: metrics-server  
 32         image: k8s.gcr.io/metrics-server-amd64:v0.3.3  
 33         imagePullPolicy: IfNotPresent  
 34         command:  
 35           - /metrics-server  
 36           - --kubelet-preferred-address-types=InternalIP,Hostname,InternalDNS,ExternalDNS,ExternalIP
 37           - --kubelet-insecure-tls  
 38         volumeMounts:  
 39         - name: tmp-dir  
 40           mountPath: /tmp  

# 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.io/v1beta1.metrics.k8s.io created 
serviceaccount/metrics-server created  
deployment.extensions/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  

三、查看pod狀態  
metrics-server-55898485b6-pdhnz               1/1     Running   0          93m    10.244.4.2      huoban-k8s-node01  

四、查看node資源使用狀況（ 必定要等幾分鐘，採集數據須要時間） 
kubectl top node  
NAME                  CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%     
huoban-k8s-master01   72m          3%     612Mi           16%         
huoban-k8s-master02   93m          4%     713Mi           19%         
huoban-k8s-master03   108m         5%     674Mi           18%         
huoban-k8s-node01     26m          1%     334Mi           9%          
huoban-k8s-node02     26m          1%     339Mi           9%        

五、查看pod資源使用狀況
# kubectl top pods -n kube-system
NAME                                          CPU(cores)   MEMORY(bytes)
coredns-6967fb4995-4qlfb                      1m           13Mi
coredns-6967fb4995-frv2p                      1m           12Mi
etcd-huoban-k8s-master01                      22m          358Mi
etcd-huoban-k8s-master02                      25m          364Mi
etcd-huoban-k8s-master03                      23m          381Mi
kube-apiserver-huoban-k8s-master01            15m          267Mi
kube-apiserver-huoban-k8s-master02            13m          255Mi
kube-apiserver-huoban-k8s-master03            17m          249Mi
kube-controller-manager-huoban-k8s-master01   7m           69Mi
kube-controller-manager-huoban-k8s-master02   0m           14Mi
kube-controller-manager-huoban-k8s-master03   0m           14Mi
kube-flannel-ds-amd64-6bp76                   1m           21Mi
kube-flannel-ds-amd64-nrvvz                   1m           15Mi
kube-flannel-ds-amd64-shv4n                   1m           16Mi
kube-flannel-ds-amd64-t77n4                   1m           15Mi
kube-proxy-8d522                              1m           19Mi
kube-proxy-9ng4j                              1m           18Mi
kube-proxy-htw7p                              1m           20Mi
kube-proxy-n9r48                              1m           17Mi
kube-proxy-nsqgh                              1m           17Mi
kube-scheduler-huoban-k8s-master01            1m           27Mi
kube-scheduler-huoban-k8s-master02            0m           16Mi
kube-scheduler-huoban-k8s-master03            0m           13Mi
kubernetes-dashboard-86844cc55f-sz4gn         0m           13Mi
metrics-server-d9d75756b-l75wj                1m           17Mi