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I've read some pages about monitoring k8s, and I found kubernetes_sd_config (within prometheus), metrics-server (took the place of heapster) and kube-state-metrics. All of them could provides metrics, but what's the difference?

  1. Does kubernetes_sd_config (within prometheus) provide all the data those I can get using metrics-server and kube-state-metrics?
  2. Is kubernetes_sd_config just enough for monitoring?
  3. Is metrics-server just for providing data (less than kubernetes_sd_config) to the internal components(such as hpa controller)?
  4. Is kube-state-metrics just for the objects (pod, deployment...) in k8s?
  5. what is their own target respectively?
SDJ
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woshilaiceshide
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1 Answers1

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1 Metrics-server is a cluster level component which periodically scrapes container CPU and memory usage metrics from all Kubernetes nodes served by Kubelet through Summary API.

The Kubelet exports a "summary" API that aggregates stats from all pods.

$ kubectl proxy &
Starting to serve on 127.0.0.1:8001
$ NODE=$(kubectl get nodes -o=jsonpath="{.items[0].metadata.name}")
$ curl localhost:8001/api/v1/proxy/nodes/${NODE}:10255/stats/summary

Use-Cases:

  • Horizontal Pod Autoscaler.
  • kubectl top --help: command.

2 kube-state-metrics

is focused on generating completely new metrics from Kubernetes' object state (e.g. metrics based on deployments, replica sets, etc.). It holds an entire snapshot of Kubernetes state in memory and continuously generates new metrics based off of it

Use-Cases

  • count the number of k8s Objects.
  • How many namespaces are there ?

sysdig-k8s-state-metrics provide the further Information.

3 Prometheus Node_Exporter − Gets the host level matrices and exposes them to Prometheus.

Use-Cases

  • User and Kernel Space level information.

Lastly, kubernetes_sd_config is the configuration file defines everything related to scraping targets.

You can decide in the config file what kind of information you want to gather and from whom.

Rot-man
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Suresh Vishnoi
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  • Thanks for your reply. SO, Could kubernetes_sd_config(within prometheus) provide all the data those I can get using metrics-server and kube-state-metrics? – woshilaiceshide Jul 05 '19 at 15:38
  • yea, these targets provides most of the data. what kind of data are you trying scrap? what is your usecase? – Suresh Vishnoi Jul 05 '19 at 16:14
  • I'm just looking for a solution targeted k8s monitoring. Now, I know that kubernetes_sd_config in prometheus is enough. If "kubectl top xxx" is wanted, then metrics_server is here. Thanks. – woshilaiceshide Jul 06 '19 at 09:17