Kubernetes如何使用带有度量服务器的HPA自动缩放？
我对在Ubuntu安装中测试kubernete自动缩放解决方案非常感兴趣。我已经在mini kube中使用过它，带有heapster，但由于它已经被弃用，我尝试使用指标服务器。现在在我的Ubuntu中，我安装了metrics-server，如下所示：
kube-system kube-apiserver-kmaster 1/1 Running 1 11d
kube-system kube-controller-manager-kmaster 1/1 Running 1 11d
kube-system kube-proxy-47k6b 1/1 Running 0 11d
kube-system kube-proxy-q8zdw 1/1 Running 1 11d
kube-system kube-scheduler-kmaster 1/1 Running 1 11d
kube-system kubernetes-dashboard-5f7b999d65-6wl6k 1/1 Running 1 11d
kube-system metrics-server-548456b4cd-wxc9b 1/1 Running 0 3d18h
metallb-system controller-cd8657667-ckpn6 1/1 Running 0 8d
metallb-system speaker-m9599
但当我检查HPA时，我总是看到以下内容：
Kubectl获得hpa
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
api-server Deployment/api-server <unknown>/50% 1 10 3 3d19h
ngsc Deployment/ngsc <unknown>/50% 1 10 3 3d19h
似乎度量服务不用于计算使用量。
我去了Kubernetes的文档站点，真的不知道如何配置metric服务器的利用率，以便Kubernetes进行自动缩放。
我描述了自动缩放：
api-server
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Fri, 03 May 2019 05:49:07 +0000
Reference: Deployment/api-server
Metrics: ( current / target )
resource cpu on pods (as a percentage of request): <unknown> / 50%
Min replicas: 1
Max replicas: 10
Deployment pods: 3 current / 0 desired
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededGetScale the HPA controller was able to get the target's current scale
ScalingActive False FailedGetResourceMetric the HPA was unable to compute the replica count: unable to get metrics for resource cpu: no metrics returned from resource metrics API
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedGetResourceMetric 4m48s (x22069 over 3d20h) horizontal-pod-autoscaler unable to get metrics for resource cpu: no metrics returned from resource metrics API
描述部署：
Pod Template:
Labels: app=api-server
Containers:
api-server:
Image: xxxxxx
Port: <none>
Host Port: <none>
Limits:
cpu: 500m
Requests:
cpu: 200m
Environment: <none>
Mounts: <none>
Volumes: <none>
这意味着部署具有资源配置。但hpa仍显示未知
添加内存，现在描述的是：
Limits:
cpu: 500m
memory: 1Gi
Requests:
cpu: 500m
memory: 512Mi
但是kubectl获得hpa仍然未知。
正在检查metrics服务器的日志：
1 manager.go:111] unable to fully collect metrics: [unable to fully scrape metrics from source kubelet_summary:kmaster: unable to fetch metrics from Kubelet kmaster (kmaster): Get https://kmaster:10250/stats/summary/: dial tcp: lookup kmaster on 10.96.0.10:53: no such host, unable to fully scrape metrics from source kubelet_summary:knode: unable to fetch metrics from Kubelet knode (knode): Get https://knode:10250/stats/summary/: dial tcp: lookup knode on 10.96.0.10:53: no such host]
E0507 05:20:23.797590 1 reststorage.go:148] unable to fetch pod metrics for pod default/api-server-777b78ccf5-mlt94: no metrics known for pod
E0507 05:20:23.797614 1 reststorage.go:148] unable to fetch pod metrics for pod default/api-server-777b78ccf5-r66bw: no metrics known for pod
以及何时
curl -k https://knode:10250/stats/summary/`
我遇到了以下错误：
Unauthorized
共有3个答案
这意味着pod没有分配给它们的任何cpu资源。没有分配的资源，HPA无法做出扩展决策。尝试向pod添加一些资源，如下所示：
spec:
containers:
- resources:
requests:
memory: "64Mi"
cpu: "250m"
limits:
memory: "128Mi"
cpu: "500m"
有时，HPA没有显示值确保metrics服务器的pod在命名空间kube系统内运行。
对我来说，有时当流量出现在网站上时，它会开始显示HPA的值。
根据您提供的信息。
由于您有pod metrics-server-548456b4cd-wxc9b，这意味着metric server已启用。另外，由于您有3个副本，我假定此数字是在部署清单中提供的。
由于以下原因，HPA可能无法扩展您的部署：
1）缺乏资源
$ kubectl describe node
...
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
default nginx-deployment-5ffb677f99-k5mdj 200m (10%) 500m (25%) 0 (0%) 0 (0%) 6m55s
default nginx-deployment-5ffb677f99-n7t7n 200m (10%) 500m (25%) 0 (0%) 0 (0%) 6m55s
default nginx-deployment-5ffb677f99-pw2g7 200m (10%) 500m (25%) 0 (0%) 0 (0%) 6m55s
kube-system etcd-minikube 0 (0%) 0 (0%) 0 (0%) 0 (0%) 152m
kube-system kube-addon-manager-minikube 5m (0%) 0 (0%) 50Mi (0%) 0 (0%) 152m
kube-system kube-apiserver-minikube 250m (12%) 0 (0%) 0 (0%) 0 (0%) 152m
kube-system kube-controller-manager-minikube 200m (10%) 0 (0%) 0 (0%) 0 (0%) 152m
kube-system kube-dns-6bfbdd666c-l74lx 260m (13%) 0 (0%) 110Mi (1%) 170Mi (2%) 32m
kube-system kube-proxy-dnh4m 0 (0%) 0 (0%) 0 (0%) 0 (0%) 153m
kube-system kube-scheduler-minikube 100m (5%) 0 (0%) 0 (0%) 0 (0%) 152m
kube-system metrics-server-77fddcc57b-mjlf5 0 (0%) 0 (0%) 0 (0%) 0 (0%) 147m
kube-system storage-provisioner 0 (0%) 0 (0%) 0 (0%) 0 (0%) 153m
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 1415m (70%) 1500m (75%)
memory 160Mi (2%) 170Mi (2%)
ephemeral-storage 0 (0%) 0 (0%)
正如您在示例中看到的那样，mini kube资源和3个带有nginx的pod已经请求了70%的CPU。在您的清单中，每个容器都将请求cpu：200m，因此此部署只能再创建2个pod。由于缺乏CPU资源，其他pod将处于Pend状态。
2）CPU负载不足
错误消息，如HPA无法计算副本计数：无法获取资源cpu的指标：没有从资源指标API返回的指标，意味着metric server没有收到任何指标，因此POD没有生成任何负载。
我假设您使用命令扩展了部署
$ kubectl autoscale deployment api-server --cpu-percent=50 --min=1 --max=10
...
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededGetScale the HPA controller was able to get the target's current scale
ScalingActive False FailedGetResourceMetric the HPA was unable to compute the replica count: unable to get metrics for resource cpu: no metrics returned from resource metrics API
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedGetResourceMetric 9s horizontal-pod-autoscaler unable to get metrics for resource cpu: no metrics returned from resource metrics API
Warning FailedComputeMetricsReplicas 9s horizontal-pod-autoscaler failed to get cpu utilization: unable to get metrics for resource cpu: no metrics returned from resource metrics API
尝试通过输入一个部署吊舱来生成一些CPU负载
$ kubectl exec -ti <yourPodName> sh
$ while true; do echo 'IncreaseLoad'; done
IncreaseLoad
IncreaseLoad
IncreaseLoad
...
也可以使用“应力”命令。
一段时间后，HPA应该获得指标并从正确的值更改。
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True ReadyForNewScale recommended size matches current size
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedGetResourceMetric 14m (x6 over 16m) horizontal-pod-autoscaler unable to get metrics for resource cpu: no metrics returned from resource metrics API
Warning FailedComputeMetricsReplicas 14m (x6 over 16m) horizontal-pod-autoscaler failed to get cpu utilization: unable to get metrics for resource cpu: no metrics returned from resource metrics API
Normal SuccessfulRescale 6m54s horizontal-pod-autoscaler New size: 2; reason: All metrics below target
Normal SuccessfulRescale 50s horizontal-pod-autoscaler New size: 4; reason: cpu resource utilization (percentage of request) above target
如果这没有帮助，请提供您的HPA和部署清单。
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