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[英]Kubernetes HPA not scaling with custom metric using prometheus adapter on istio
[英]How to use Istio's Prometheus to configure kubernetes hpa?
我们有一个Istio集群,我们正在尝试为Kubernetes配置水平容器自动缩放。 我们希望将请求计数用作hpa的自定义指标。 我们如何才能将Istio的Prometheus用于同一目的?
事实证明,这个问题比我预期的要复杂得多,但最终我得到了答案。
首先,您需要配置您的应用程序以提供自定义指标。 它在开发应用程序方面。 这是一个如何使用Go语言制作示例: 使用Prometheus观看指标
其次,您需要定义应用程序部署(或Pod或任何您想要的部署)并将其部署到Kubernetes,例如:
apiVersion: extensions/v1beta1 kind: Deployment metadata: name: podinfo spec: replicas: 2 template: metadata: labels: app: podinfo annotations: prometheus.io/scrape: 'true' spec: containers: - name: podinfod image: stefanprodan/podinfo:0.0.1 imagePullPolicy: Always command: - ./podinfo - -port=9898 - -logtostderr=true - -v=2 volumeMounts: - name: metadata mountPath: /etc/podinfod/metadata readOnly: true ports: - containerPort: 9898 protocol: TCP readinessProbe: httpGet: path: /readyz port: 9898 initialDelaySeconds: 1 periodSeconds: 2 failureThreshold: 1 livenessProbe: httpGet: path: /healthz port: 9898 initialDelaySeconds: 1 periodSeconds: 3 failureThreshold: 2 resources: requests: memory: "32Mi" cpu: "1m" limits: memory: "256Mi" cpu: "100m" volumes: - name: metadata downwardAPI: items: - path: "labels" fieldRef: fieldPath: metadata.labels - path: "annotations" fieldRef: fieldPath: metadata.annotations --- apiVersion: v1 kind: Service metadata: name: podinfo labels: app: podinfo spec: type: NodePort ports: - port: 9898 targetPort: 9898 nodePort: 31198 protocol: TCP selector: app: podinfo
注意字段annotations: prometheus.io/scrape: 'true'
。 需要请求Prometheus从资源中读取指标。 另请注意,还有两个其他注释,它们具有默认值; 但是如果您在应用程序中更改了它们,则需要为它们添加正确的值:
prometheus.io/path
:如果度量标准路径不是/ metrics,则使用此注释对其进行定义。 prometheus.io/port
:在指示的端口上刮除Pod,而不是Pod的声明的端口(如果未声明,则默认为无端口目标)。 接下来,Istio中的Prometheus使用自己修改的用于Istio目的的配置,默认情况下,它会跳过Pod中的自定义指标。 因此,您需要对其进行一些修改。 就我而言,我从此示例中获取Pod指标的配置,并仅针对Pod修改了Istio的Prometheus配置:
kubectl edit configmap -n istio-system prometheus
我根据前面提到的示例更改了标签的顺序:
# pod's declared ports (default is a port-free target if none are declared). - job_name: 'kubernetes-pods' # if you want to use metrics on jobs, set the below field to # true to prevent Prometheus from setting the `job` label # automatically. honor_labels: false kubernetes_sd_configs: - role: pod # skip verification so you can do HTTPS to pods tls_config: insecure_skip_verify: true # make sure your labels are in order relabel_configs: # these labels tell Prometheus to automatically attach source # pod and namespace information to each collected sample, so # that they'll be exposed in the custom metrics API automatically. - source_labels: [__meta_kubernetes_namespace] action: replace target_label: namespace - source_labels: [__meta_kubernetes_pod_name] action: replace target_label: pod # these labels tell Prometheus to look for # prometheus.io/{scrape,path,port} annotations to configure # how to scrape - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape] action: keep regex: true - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_path] action: replace target_label: __metrics_path__ regex: (.+) - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port] action: replace regex: ([^:]+)(?::\\d+)?;(\\d+) replacement: $1:$2 target_label: __address__ - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scheme] action: replace target_label: __scheme__
此后,自定义指标出现在Prometheus中。 但是,请谨慎更改Prometheus配置 ,因为Istio所需的某些指标可能会消失,请仔细检查所有内容。
现在该安装Prometheus定制度量适配器了 。
<repository-directory>/deploy/manifests/custom-metrics-apiserver-deployment.yaml
更改Prometheus服务器的地址。 例如- --prometheus-url=http://prometheus.istio-system:9090/
kubectl apply -f <repository-directory>/deploy/manifests
一段时间后, custom.metrics.k8s.io/v1beta1
kubectl apply -f <repository-directory>/deploy/manifests
custom.metrics.k8s.io/v1beta1
应该出现在命令“ kubectl api-vesions”的输出中。 另外,使用命令kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq .
检查自定义API的输出。 kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq .
和kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1/namespaces/default/pods/*/http_requests" | jq .
kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1/namespaces/default/pods/*/http_requests" | jq .
下一个示例的输出应类似于以下示例:
{ "kind": "MetricValueList", "apiVersion": "custom.metrics.k8s.io/v1beta1", "metadata": { "selfLink": "/apis/custom.metrics.k8s.io/v1beta1/namespaces/default/pods/%2A/http_requests" }, "items": [ { "describedObject": { "kind": "Pod", "namespace": "default", "name": "podinfo-6b86c8ccc9-kv5g9", "apiVersion": "/__internal" }, "metricName": "http_requests", "timestamp": "2018-01-10T16:49:07Z", "value": "901m" }, { "describedObject": { "kind": "Pod", "namespace": "default", "name": "podinfo-6b86c8ccc9-nm7bl", "apiVersion": "/__internal" }, "metricName": "http_requests", "timestamp": "2018-01-10T16:49:07Z", "value": "898m" } ] }
如果是这样,则可以转到下一步。 如果不是,请在CustomMetrics kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "pods/"
查看可用于Pod的API的kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "pods/"
kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "pods/"
kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "pods/"
和http_requests kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "http"
kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "http"
kubectl get --raw "/apis/custom.metrics.k8s.io/v1beta1" | jq . | grep "http"
。 MetricNames是根据Prometheus从Pods收集的度量标准生成的,如果它们为空,则需要朝该方向查看。
最后一步是配置HPA并对其进行测试。 因此,就我而言,我为podinfo应用程序创建了HPA,该应用程序之前已定义:
apiVersion: autoscaling/v2beta1 kind: HorizontalPodAutoscaler metadata: name: podinfo spec: scaleTargetRef: apiVersion: extensions/v1beta1 kind: Deployment name: podinfo minReplicas: 2 maxReplicas: 10 metrics: - type: Pods pods: metricName: http_requests targetAverageValue: 10
并使用简单的Go应用程序来测试负载:
#install hey go get -u github.com/rakyll/hey #do 10K requests rate limited at 25 QPS hey -n 10000 -q 5 -c 5 http://<K8S-IP>:31198/healthz
一段时间后,我看到通过使用命令kubectl describe hpa
和kubectl get hpa
进行缩放的更改
我使用了使用Kubernetes Horizontal Pod Autoscaler和Prometheus确保高可用性和正常运行时间一文中有关创建自定义指标的说明
所有有用的链接都放在一个地方:
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