2.4.5. 使用 CLI 了解 pod 横向自动扩展状态条件

您可以使用设置的状态条件来判断 pod 横向自动扩展 (HPA) 是否能够缩放，以及目前是否受到某种方式的限制。

HPA 状态条件可通过 v2beta1 版的自动扩展 API 使用。

HPA 可以通过下列状态条件给予响应：

  • AbleToScale 条件指示 HPA 是否能够获取和更新指标，以及是否有任何与退避相关的条件阻碍了缩放。

    • True 条件表示允许缩放。
    • False 条件表示因为指定原因不允许缩放。

  • ScalingActive 条件指示 HPA 是否已启用（例如，目标的副本数不为零），并且可以计算所需的指标。

    • True 条件表示指标工作正常。
    • False 条件通常表示获取指标时出现问题。

  • ScalingLimited 条件表示所需的规模由 pod 横向自动扩展限定最大或最小限制。

    • True 条件表示您需要提高或降低最小或最大副本数才能进行缩放。

    • False 条件表示允许请求的缩放。 

      $ oc describe hpa cm-test

      输出示例

      Name:                           cm-test
Namespace:                      prom
Labels:                         <none>
Annotations:                    <none>
CreationTimestamp:              Fri, 16 Jun 2017 18:09:22 +0000
Reference:                      ReplicationController/cm-test
Metrics:                        ( current / target )
  "http_requests" on pods:      66m / 500m
Min replicas:                   1
Max replicas:                   4
ReplicationController pods:     1 current / 1 desired
Conditions: 1
  Type              Status    Reason              Message
  ----              ------    ------              -------
  AbleToScale       True      ReadyForNewScale    the last scale time was sufficiently old as to warrant a new scale
  ScalingActive     True      ValidMetricFound    the HPA was able to successfully calculate a replica count from pods metric http_request
  ScalingLimited    False     DesiredWithinRange  the desired replica count is within the acceptable range
Events:

      1
      pod 横向自动扩展状态消息。

下例中是一个无法缩放的 pod：

输出示例

Conditions:
  Type         Status  Reason          Message
  ----         ------  ------          -------
  AbleToScale  False   FailedGetScale  the HPA controller was unable to get the target's current scale: no matches for kind "ReplicationController" in group "apps"
Events:
  Type     Reason          Age               From                       Message
  ----     ------          ----              ----                       -------
  Warning  FailedGetScale  6s (x3 over 36s)  horizontal-pod-autoscaler  no matches for kind "ReplicationController" in group "apps"

下例中是一个无法获得缩放所需指标的 pod：

输出示例

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: failed to get cpu utilization: unable to get metrics for resource cpu: no metrics returned from resource metrics API

下例中是一个请求的自动缩放低于所需下限的 pod：

输出示例

Conditions:
  Type              Status    Reason              Message
  ----              ------    ------              -------
  AbleToScale       True      ReadyForNewScale    the last scale time was sufficiently old as to warrant a new scale
  ScalingActive     True      ValidMetricFound    the HPA was able to successfully calculate a replica count from pods metric http_request
  ScalingLimited    False     DesiredWithinRange  the desired replica count is within the acceptable range

2.4.5.1. 使用 CLI 查看 pod 横向自动扩展状态条件

您可以查看 pod 横向自动扩展 (HPA) 对 pod 设置的状态条件。

注意

pod 横向自动扩展状态条件可通过 v2beta1 版的自动扩展 API 使用。

先决条件

要使用 pod 横向自动扩展，您的集群管理员必须已经正确配置了集群指标。您可以使用 oc describe PodMetrics <pod-name> 命令来判断是否已配置了指标。如果配置了指标，输出类似于以下示例，其中 Usage 下列出了 Cpu 和 Memory。 

$ oc describe PodMetrics openshift-kube-scheduler-ip-10-0-135-131.ec2.internal

输出示例

Name:         openshift-kube-scheduler-ip-10-0-135-131.ec2.internal
Namespace:    openshift-kube-scheduler
Labels:       <none>
Annotations:  <none>
API Version:  metrics.k8s.io/v1beta1
Containers:
  Name:  wait-for-host-port
  Usage:
    Memory:  0
  Name:      scheduler
  Usage:
    Cpu:     8m
    Memory:  45440Ki
Kind:        PodMetrics
Metadata:
  Creation Timestamp:  2019-05-23T18:47:56Z
  Self Link:           /apis/metrics.k8s.io/v1beta1/namespaces/openshift-kube-scheduler/pods/openshift-kube-scheduler-ip-10-0-135-131.ec2.internal
Timestamp:             2019-05-23T18:47:56Z
Window:                1m0s
Events:                <none>

流程

要查看 pod 上的状态条件，请使用以下命令并提供 pod 的名称： 

$ oc describe hpa <pod-name>

例如： 

$ oc describe hpa cm-test

这些条件会出现在输出中的 Conditions 字段里。

输出示例

Name:                           cm-test
Namespace:                      prom
Labels:                         <none>
Annotations:                    <none>
CreationTimestamp:              Fri, 16 Jun 2017 18:09:22 +0000
Reference:                      ReplicationController/cm-test
Metrics:                        ( current / target )
  "http_requests" on pods:      66m / 500m
Min replicas:                   1
Max replicas:                   4
ReplicationController pods:     1 current / 1 desired
Conditions: 1
  Type              Status    Reason              Message
  ----              ------    ------              -------
  AbleToScale       True      ReadyForNewScale    the last scale time was sufficiently old as to warrant a new scale
  ScalingActive     True      ValidMetricFound    the HPA was able to successfully calculate a replica count from pods metric http_request
  ScalingLimited    False     DesiredWithinRange  the desired replica count is within the acceptable range