Kubernetes Heapster

故事的起因

最近备考cka，做实验的时候发现运行kubectl top时无法正常运行。
报错如下：

[root@k8s-master ~]# kubectl top pods
Error from server (NotFound): the server could not find the requested resource (get services http:heapster:)

报错原因

Heapster是容器集群监控和性能分析工具，HPA、Dashborad、Kubectl top都依赖于heapster收集的数据。
但是Heapster从kubernetes 1.8以后已经被遗弃了… 被metrics-server所替代…

那么就部署一下Heapster吧

两个yaml文件内容如下：

[root@k8s-master ~]# cat heapster.yaml 
apiVersion: v1
kind: ServiceAccount
metadata:
  name: heapster
  namespace: kube-system

---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: heapster
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:heapster
subjects:
- kind: ServiceAccount
  name: heapster
  namespace: kube-system

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: heapster
  namespace: kube-system
spec:
  replicas: 1
  selector:
      matchLabels:
        k8s-app: heapster
  template:
    metadata:
      labels:
        task: monitoring
        k8s-app: heapster
    spec:
      serviceAccountName: heapster
      containers:
      - name: heapster
        # image: k8s.gcr.io/heapster-amd64:v1.5.4 将默认google的官方镜像替换为阿里云镜像，否则你懂得
        image: registry.cn-hangzhou.aliyuncs.com/google_containers/heapster-amd64:v1.5.4
        command:
        - /heapster
        - --source=kubernetes:https://kubernetes.default?useServiceAccount=true&kubeletHttps=true&kubeletPort=10250&insecure=true
---
apiVersion: v1
kind: Service
metadata:
  labels:
    task: monitoring
    # For use as a Cluster add-on (https://github.com/kubernetes/kubernetes/tree/master/cluster/addons)
    # If you are NOT using this as an add-on, you should comment out this line.
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: Heapster
  name: heapster
  namespace: kube-system
spec:
  ports:
  - port: 80
    targetPort: 8082
  selector:
    k8s-app: heapster

[root@k8s-master ~]# cat heapster-clusterrole.yaml 
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
  labels:
    kubernetes.io/bootstrapping: rbac-defaults
  name: system:heapster
rules:
- apiGroups:
  - ""
  resources:
  - events
  - namespaces
  - nodes
  - pods
  - nodes/stats
  verbs:
  - create
  - get
  - list
  - watch
- apiGroups:
  - extensions
  resources:
  - deployments
  verbs:
  - get
  - list
  - watch

部署Heapster

[root@k8s-master ~]# kubectl apply -f heapster-clusterrole.yaml
[root@k8s-master ~]# kubectl apply -f heapster.yaml
[root@k8s-master ~]# kubectl get pods -n kube-system
heapster-5ff6f69d68-cgq5j             1/1     Running       0          10s

[root@k8s-master ~]# kubectl top pods -n kube-system
NAME                                  CPU(cores)   MEMORY(bytes)   
coredns-bccdc95cf-4fpls               3m           15Mi            
coredns-bccdc95cf-plxlr               3m           17Mi            
etcd-k8s-master                       42m          101Mi           
heapster-5ff6f69d68-g4bxs             0m           22Mi            
kube-apiserver-k8s-master             68m          268Mi           
kube-controller-manager-k8s-master    34m          58Mi            
kube-flannel-ds-amd64-5lkh6           2m           20Mi            
kube-flannel-ds-amd64-fpw6k           2m           21Mi            
kube-flannel-ds-amd64-snngf           2m           19Mi            
kube-proxy-glrtz                      2m           27Mi            
kube-proxy-jdcpf                      2m           25Mi            
kube-proxy-tcsk2                      2m           23Mi            
kube-scheduler-k8s-master             1m           20Mi            
kube-state-metrics-7c76bdbf68-r685j   0m           30Mi            
kubernetes-dashboard-79ddd5-pdjsl     0m           13Mi

模拟开题

考题的内容大概是：从label xxx=xxx，中找出cpu 最高的pod，将pod名输出到xxx文件。

[root@k8s-master ~]# kubectl top pods -n kube-system -l app=flannel
NAME                          CPU(cores)   MEMORY(bytes)   
kube-flannel-ds-amd64-5lkh6   2m           20Mi            
kube-flannel-ds-amd64-fpw6k   2m           21Mi            
kube-flannel-ds-amd64-snngf   2m           19Mi  
[root@k8s-master ~]# kubectl top pods -n kube-system -l app=flannel|grep -i kube-flannel|head -n 1|awk '{print $1}'
kube-flannel-ds-amd64-5lkh6
[root@k8s-master ~]# kubectl top pods -n kube-system -l app=flannel|grep -i kube-flannel|head -n 1|awk '{print $1}' > 666.txt 

差不多就是这样