CODEWITHSUNDEEP
kubernetesprometheushpa
Ravi Shah
Ravi Shah

Reputation: 82

How to check external metrics data in Kubernetes?

I am using DirectXMan12/k8s-prometheus-adapte to push the external metric from Prometheus to Kubernetes.

After pushing the external metric how can I verify the data is k8s?

When I hit kubectl get --raw /apis/external.metrics.k8s.io/v1beta1 | jq I got the following result but after that, I do not have an idea how to fetch actual metrics value

{
  "kind": "APIResourceList",
  "apiVersion": "v1",
  "groupVersion": "external.metrics.k8s.io/v1beta1",
  "resources": [
   {
     "name": "subscription_back_log",
     "singularName": "",
     "namespaced": true,
     "kind": "ExternalMetricValueList",
     "verbs": [
       "get"
     ]
  }]
}

Upvotes: 2

Views: 4096

Answers (2)

Jasper Kuperus
Jasper Kuperus

Reputation: 1692

The metric is namespaced, so you will need to add the namespace into the URL. Contrary to what the other answer suggests, I believe you don't need to include pods into the URL. This is an external metric. External metrics are not associated to any kubernetes object, so only the namespace should suffice:

  • /apis/external.metrics.k8s.io/v1beta1/namespaces/<namespace>/<metric_name>

Here's an example that works for me, using an external metric in my setup:

$ kubectl get --raw /apis/external.metrics.k8s.io/v1beta1 | jq                                               
{
  "kind": "APIResourceList",
  "apiVersion": "v1",
  "groupVersion": "external.metrics.k8s.io/v1beta1",
  "resources": [
    {
      "name": "redis_key_size",
      "singularName": "",
      "namespaced": true,
      "kind": "ExternalMetricValueList",
      "verbs": [
        "get"
      ]
    }
  ]
}

$ kubectl get --raw /apis/external.metrics.k8s.io/v1beta1/namespaces/default/redis_key_size

{
  "kind": "ExternalMetricValueList",
  "apiVersion": "external.metrics.k8s.io/v1beta1",
  "metadata": {},
  "items": [
    {
      "metricName": "redis_key_size",
      "metricLabels": {
        "key": "..."
      },
      "timestamp": "2021-10-07T09:00:01Z",
      "value": "0"
    },
    ...
  ]
}

Upvotes: 1

Efrat Levitan
Efrat Levitan

Reputation: 5612

actual metric value is fetched per instance, for example, the metric you attached is namespaced: true, assuming the metric is for pods, you can access the actual data at 

kubectl get --raw "/apis/external.metrics.k8s.io/v1beta1/namespaces/wanted_namepsace/pods/*/subscription_back_log" | jq '.'

(or specify the pod name instead of *)

If you want HPA to read you metric, the configurations are (for example)

apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: your-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: your-pod
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - pods:
      metricName: subscription_back_log
      targetAverageValue: 10000
    type: Pods

Upvotes: 1

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