• Kubernetes 基于 Metrics Server 与 HPA 的使用


    image

    在 Kubernetes 中可以手动通过 kubectl scale 命令或通过修改 replicas 数量,可以实现 Pod 的扩容或缩容。Kubernetes 中还提供了 HPA(Horizontal Pod Autoscaling) 功能,可以根据当前负载的变化情况自动触发水平扩展或缩容的行为,从而合理的使用资源。从 Kubernetes  v1.8 开始,资源使用情况的度量(如容器的 CPU 和内存使用)可以通过 Metrics API 获取,HPA 使用这些 metics 信息来实现动态伸缩。

    拉取镜像

    $ touch pull_k8s_images.sh
    
    #!/bin/bash
    images=(metrics-server-amd64:v0.3.1)
    for imageName in ${images[@]} ; do
    docker pull anjia0532/google-containers.$imageName
    docker tag anjia0532/google-containers.$imageName k8s.gcr.io/$imageName
    docker rmi anjia0532/google-containers.$imageName
    done
    
    $ sh touch pull_k8s_images.sh

    部署 metrics-server

    $ git clone https://github.com/kubernetes-incubator/metrics-server.git
    $ cd metrics-server
    $ kubectl create -f deploy/1.8+/
    
    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

    上述可能还会提示拉取不到镜像,由于配置了 imagePullPolicy: Always,可以注释掉

    vi 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: k8s.gcr.io/metrics-server-amd64:v0.3.1
           # imagePullPolicy: Always
            volumeMounts:
            - name: tmp-dir
              mountPath: /tmp

    执行查看

    $ kubectl apply -f metrics-server-deployment.yaml
    $ kubectl get pod,svc -n kube-system
    NAME                                            READY   STATUS    RESTARTS   AGE
    pod/coredns-576cbf47c7-d6tm2                    1/1     Running   0          14d
    pod/coredns-576cbf47c7-zgdsx                    1/1     Running   0          14d
    pod/etcd-kubernetes-master                      1/1     Running   0          14d
    pod/kube-apiserver-kubernetes-master            1/1     Running   0          14d
    pod/kube-controller-manager-kubernetes-master   1/1     Running   1          14d
    pod/kube-proxy-dz4fh                            1/1     Running   0          14d
    pod/kube-proxy-qh9b5                            1/1     Running   0          14d
    pod/kube-proxy-x8clc                            1/1     Running   0          14d
    pod/kube-scheduler-kubernetes-master            1/1     Running   1          14d
    pod/kubernetes-dashboard-77fd78f978-qp626       1/1     Running   0          14d
    pod/metrics-server-79f8f467b5-6l5wh             1/1     Running   0          10m
    pod/tiller-deploy-7788856dfb-7kkw7              1/1     Running   0          11d
    pod/traefik-ingress-controller-qjnc6            1/1     Running   0          12d
    pod/traefik-ingress-controller-rwxr6            1/1     Running   0          12d
    pod/weave-net-j9s27                             2/2     Running   0          6d11h
    pod/weave-net-p22s2                             2/2     Running   0          6d11h
    pod/weave-net-vnq7p                             2/2     Running   0          6d11h
    
    NAME                              TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)           AGE
    service/kube-dns                  ClusterIP   10.96.0.10       <none>        53/UDP,53/TCP     14d
    service/kubernetes-dashboard      NodePort    10.103.60.159    <none>        443:32151/TCP     14d
    service/metrics-server            ClusterIP   10.110.180.222   <none>        443/TCP           42m
    service/tiller-deploy             ClusterIP   10.103.123.198   <none>        44134/TCP         11d
    service/traefik-ingress-service   ClusterIP   10.105.18.62     <none>        80/TCP,8080/TCP   12d
    service/traefik-web-ui            ClusterIP   10.102.207.196   <none>        80/TCP            12d

    配置 HPA

    vi vi nginx-deployment-hpa.yaml
    
    apiVersion: autoscaling/v1
    kind: HorizontalPodAutoscaler
    metadata:
      name: nginx-deployment-hpa
      namespace: default
    spec:
      maxReplicas: 10
      minReplicas: 4
      scaleTargetRef:
        kind: Deployment
        name: nginx-deployment
      targetCPUUtilizationPercentage: 50 # CPUUtilizationPercentage 是一个平均值,即 Pod 所有副本自身的 CPU 利用率的平均值。

    备注:Kubernetes v1.2 版本中 HPA 升级为稳定版本(apiVersion: autoscaling/v1),等同于 kubectl autoscale deployment nginx-deployment--cpu-percent=50 --min=4 --max=10

    执行查看

    kubectl apply -f nginx-deployment-hpa.yaml
    $ kubectl get hpa
    NAME                   REFERENCE                     TARGETS         MINPODS   MAXPODS   REPLICAS   AGE
    nginx-deployment-hpa   Deployment/nginx-deployment   <unknown>/50%   4         10        0          11s

    REFER:
    https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#autoscale
    https://github.com/kubernetes-incubator/metrics-server
    https://github.com/stefanprodan/k8s-prom-hpa
    http://blog.51cto.com/ylw6006/2114338
    https://www.kubernetes.org.cn/4664.html

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  • 原文地址:https://www.cnblogs.com/Irving/p/9954801.html
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