HPA無法從自定義指標API中獲取指標

Question

我已經設置了Prometheus適配器以能夠將Prometheus指標用作kubernetes中的自定義指標，但是在使用Object HPA自動擴展部署時遇到了問題。

在這里，我從custom-metrics api獲得的所有內容。

```
kubectl get --raw /apis/custom.metrics.k8s.io/v1beta1/ | jq .
{
  "kind": "APIResourceList",
  "apiVersion": "v1",
  "groupVersion": "custom.metrics.k8s.io/v1beta1",
  "resources": [
    {
      "name": "services/kong_http_status_per_second",
      "singularName": "",
      "namespaced": false,
      "kind": "MetricValueList",
      "verbs": [
        "get"
      ]
    }
  ]
}
```

```
kubectl get --raw /apis/custom.metrics.k8s.io/v1beta1/services/*/kong_http_status_per_second | jq .
{
  "kind": "MetricValueList",
  "apiVersion": "custom.metrics.k8s.io/v1beta1",
  "metadata": {
    "selfLink": "/apis/custom.metrics.k8s.io/v1beta1/services/%2A/kong_http_status_per_second"
  },
  "items": [
    {
      "describedObject": {
        "kind": "Service",
        "name": "httpbin",
        "apiVersion": "/v1"
      },
      "metricName": "kong_http_status_per_second",
      "timestamp": "2019-01-08T10:30:25Z",
      "value": "339m"
    },
    {
      "describedObject": {
        "kind": "Service",
        "name": "httpbin",
        "apiVersion": "/v1"
      },
      "metricName": "kong_http_status_per_second",
      "timestamp": "2019-01-08T10:30:25Z",
      "value": "339m"
    }
  ]
```

然后是我的HPA：

```
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: httpbin
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: httpbin
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Object
    object: 
      metricName: kong_http_status_per_second
      target: 
        apiVersion: v1
        kind: Service
        name: httpbin
      targetValue: 1
```
```
kubectl describe hpa
Name:                                                httpbin
Namespace:                                           lgrondin
Labels:                                              <none>
Annotations:                                         kubectl.kubernetes.io/last-applied-configuration:
                                                       {"apiVersion":"autoscaling/v2beta1","kind":"HorizontalPodAutoscaler","metadata":{"annotations":{},"name":"httpbin","namespace":"lgrondin"}...
CreationTimestamp:                                   Tue, 08 Jan 2019 10:22:24 +0100
Reference:                                           Deployment/httpbin
Metrics:                                             ( current / target )
  "kong_http_status_per_second" on Service/httpbin:  <unknown> / 1
Min replicas:                                        2
Max replicas:                                        10
Deployment pods:                                     2 current / 2 desired
Conditions:
  Type           Status  Reason                 Message
  ----           ------  ------                 -------
  AbleToScale    True    SucceededGetScale      the HPA controller was able to get the target's current scale
  ScalingActive  False   FailedGetObjectMetric  the HPA was unable to compute the replica count: unable to get metric kong_http_status_per_second: Service on lgrondin httpbin/unable to fetch metrics from custom metrics API: the server could not find the metric kong_http_status_per_second for services
Events:
  Type     Reason                 Age                    From                       Message
  ----     ------                 ----                   ----                       -------
  Warning  FailedGetObjectMetric  87s (x449 over 4h31m)  horizontal-pod-autoscaler  unable to get metric kong_http_status_per_second: Service on lgrondin httpbin/unable to fetch metrics from custom metrics API: the server could not find the metric kong_http_status_per_second for services
```

似乎我可以通過直接調用api來獲取指標，但是HPA無法檢索指標。

謝謝你的幫助。

Answer 1

當我遇到類似的問題時，我的問題是我嘗試擴展的部署不是產生我所依賴的指標的部署。
在我的情況下，我想縮放一個吊艙，這對我有用

1. 我向我保證，嘗試擴展的Pod是部署的一部分。
2. 我保證該Pod可以在特定端口上公開所需的指標，而Prometheus會使用注釋將其刪除。
3. 我保證該部署與Hpa pod在同一名稱空間上。