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Kubernetes: 16. Monitor Cluster Component

 Cluster Components

  • Kubernetes does not have a OOB monitoring for its own cluster component
  • Node health, node resources - CPU, Memory and Disk space are some of the resources you want to monitor
  • Pod health, pod resources - CPU, Memory and Disk space are some of the resources you want to monitor
  • This may change or might have already changed in the latest versions
  • There are some good open source solutions for monitoring these components and doing analytics on them
Metrics Server
  • Heapster was one of the original project to monitor resource consumption, it was then replaced with Metrics Server
  • Metrics Server is an IN MEMORY solution. 
  • It aggregates and stores all the nodes and pod resources information
  • So there is no historical data with metrics server
  • Kubelet service is responsible to listen to the kube-api service instructions to build the pods
  • Kubelet also has other responsibilities, one of it is cAdvisor (container advisor)
  • cAdvisor collects the resource information from nodes and pods and passes these details to the Metrics Server
Enable Metrics Server
  • For a Minikube environment enable the metrics-server using mini kube addons feature
  • For rest of the environments clone the git and create the resources
  • Note that there will be multiple resources created when metrics server is enabled (pods/roles/service accounts/deployments etc)
  • These services are used to collect the resource information on the node
  • Once metric-server is deployed give it some time to collect the resources
  • Then run the top command to see the cluster performance

minikube addons enable metrics-server 
-> Enable metrics server when using minikube tool

git clone https://github.com/kubernetes-incubator/metrics-server.git 
-> For all other environments clone the definition file from git

kubectl create -f deploy/1.8+/ 
-> Create the resources (there will be multiple)

kubectl top nodes
-> Get the node level cluster performance

kubectl top pods -n <namespace>
-> Get the pod level cluster performance in the namespace

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