In our previous guide we discussed about the installation of Kubernetes Cluster on AWS by using Amazon EKS service. It is actually the quickest and easiest method of having a running Kubernetes Cluster in AWS within minutes. The setup process is fairly automated with eksctl which uses CloudFormation stacks behind the scene to bootstrap a working cluster powered by Amazon Linux worker machines.
In this tutorial I’ll walk you through the steps of installing and configuring Kubernetes metrics server in an EKS cluster. Metrics Server is a scalable, efficient source of container resource metrics for Kubernetes built-in autoscaling pipelines. It collects resource metrics from Kubelets and exposes them in Kubernetes apiserver through Metrics API for use by Horizontal Pod Autoscaler and Vertical Pod Autoscaler.
Metrics Server offers:
- A single deployment that works on most clusters
- Scalable support up to 5,000 node clusters
- Resource efficiency: Metrics Server uses 0.5m core of CPU and 4 MB of memory per node
Before you begin installation of Kubernetes Metrics Server on Amazon EKS Cluster confirm you have an EKS cluster working. You can use eksctl command to check available EKS clusters.
$ eksctl get cluster
NAME REGION
prod-eks-cluster eu-west-1If you have kubeconfig locally, use it to confirm Kubernetes API server is responsive.
$ kubectl --kubeconfig=/Users/jkmutai/.kube/eksctl/clusters/prod-eks-cluster get nodes
NAME STATUS ROLES AGE VERSION
ip-192-168-138-244.eu-west-1.compute.internal Ready 13h v1.17.9-eks-4c6976
ip-192-168-176-247.eu-west-1.compute.internal Ready 13h v1.17.9-eks-4c6976Metrics Server Requirements
Metrics Server has specific requirements for cluster and network configuration. These requirements aren’t the default for all cluster distributions. Please ensure that your cluster distribution supports these requirements before using Metrics Server:
- Metrics Server must be reachable from kube-apiserver
- The kube-apiserver must be correctly configured to enable an aggregation layer
- Nodes must have kubelet authorization configured to match Metrics Server configuration
- Container runtime must implement a container metrics RPCs
How To Install Kubernetes Metrics Server on Amazon EKS Cluster
Save your kubeconfig to environment variable.
export KUBECONFIG=/Users/jkmutai/.kube/eksctl/clusters/prod-eks-clusterConfirm you can run kubectl command without manually passing the path to your kubeconfig file.
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ip-192-168-138-244.eu-west-1.compute.internal Ready 13h v1.17.9-eks-4c6976
ip-192-168-176-247.eu-west-1.compute.internal Ready 13h v1.17.9-eks-4c6976Apply Metrics Server manifests which are available on Metrics Server releases making them installable via url:
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.7/components.yamlHere is the output of the resources being created.
clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created
clusterrolebinding.rbac.authorization.k8s.io/metrics-server:system:auth-delegator created
rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created
apiservice.apiregistration.k8s.io/v1beta1.metrics.k8s.io created
serviceaccount/metrics-server created
deployment.apps/metrics-server created
service/metrics-server created
clusterrole.rbac.authorization.k8s.io/system:metrics-server created
clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server createdUse the following command to verify that the metrics-server deployment is running the desired number of pods:
$ kubectl get deployment metrics-server -n kube-system
NAME READY UP-TO-DATE AVAILABLE AGE
metrics-server 1/1 1 1 7m23s
$ kubectl get pods -n kube-system | grep metrics
metrics-server-7cb45bbfd5-kbrt7 1/1 Running 0 8m42sConfirm Metrics server is active.
$ kubectl get apiservice v1beta1.metrics.k8s.io -o yaml
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"apiregistration.k8s.io/v1beta1","kind":"APIService","metadata":{"annotations":{},"name":"v1beta1.metrics.k8s.io"},"spec":{"group":"metrics.k8s.io","groupPriorityMinimum":100,"insecureSkipTLSVerify":true,"service":{"name":"metrics-server","namespace":"kube-system"},"version":"v1beta1","versionPriority":100}}
creationTimestamp: "2020-08-12T11:27:13Z"
name: v1beta1.metrics.k8s.io
resourceVersion: "130943"
selfLink: /apis/apiregistration.k8s.io/v1/apiservices/v1beta1.metrics.k8s.io
uid: 83c44e41-6346-4dff-8ce2-aff665199209
spec:
group: metrics.k8s.io
groupPriorityMinimum: 100
insecureSkipTLSVerify: true
service:
name: metrics-server
namespace: kube-system
port: 443
version: v1beta1
versionPriority: 100
status:
conditions:
- lastTransitionTime: "2020-08-12T11:27:18Z"
message: all checks passed
reason: Passed
status: "True"
type: AvailableMetrics API can also be accessed by using the kubectl top command. This makes it easier to debug autoscaling pipelines.
$ kubectl top --help
Display Resource (CPU/Memory/Storage) usage.
The top command allows you to see the resource consumption for nodes or pods.
This command requires Metrics Server to be correctly configured and working on the server.
Available Commands:
node Display Resource (CPU/Memory/Storage) usage of nodes
pod Display Resource (CPU/Memory/Storage) usage of pods
Usage:
kubectl top [flags] [options]
Use "kubectl --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).To display cluster nodes resource usage – CPU/Memory/Storage you’ll run the command:
$ kubectl top nodes
NAME CPU(cores) CPU% MEMORY(bytes) MEMORY%
ip-192-168-138-244.eu-west-1.compute.internal 50m 2% 445Mi 13%
ip-192-168-176-247.eu-west-1.compute.internal 58m 3% 451Mi 13%Similar command can be used for pods.
$ kubectl top pods -A
NAMESPACE NAME CPU(cores) MEMORY(bytes)
kube-system aws-node-glfrs 4m 51Mi
kube-system aws-node-sgh8p 5m 51Mi
kube-system coredns-6987776bbd-2mgxp 2m 6Mi
kube-system coredns-6987776bbd-vdn8j 2m 6Mi
kube-system kube-proxy-5glzs 1m 7Mi
kube-system kube-proxy-hgqm5 1m 8Mi
kube-system metrics-server-7cb45bbfd5-kbrt7 1m 11MiYou can also access use kubectl get –raw to pull raw resource usage metrics for all nodes in the cluster.
$ kubectl get --raw "https://computingforgeeks.com/apis/metrics.k8s.io/v1beta1/nodes" | jq
{
"kind": "NodeMetricsList",
"apiVersion": "metrics.k8s.io/v1beta1",
"metadata": {
"selfLink": "https://computingforgeeks.com/apis/metrics.k8s.io/v1beta1/nodes"
},
"items": [
{
"metadata": {
"name": "ip-192-168-176-247.eu-west-1.compute.internal",
"selfLink": "https://computingforgeeks.com/apis/metrics.k8s.io/v1beta1/nodes/ip-192-168-176-247.eu-west-1.compute.internal",
"creationTimestamp": "2020-08-12T11:44:41Z"
},
"timestamp": "2020-08-12T11:44:17Z",
"window": "30s",
"usage": {
"cpu": "55646953n",
"memory": "461980Ki"
}
},
{
"metadata": {
"name": "ip-192-168-138-244.eu-west-1.compute.internal",
"selfLink": "https://computingforgeeks.com/apis/metrics.k8s.io/v1beta1/nodes/ip-192-168-138-244.eu-west-1.compute.internal",
"creationTimestamp": "2020-08-12T11:44:41Z"
},
"timestamp": "2020-08-12T11:44:09Z",
"window": "30s",
"usage": {
"cpu": "47815890n",
"memory": "454944Ki"
}
}
]
}In our next article we’ll see how you can configure Horizontal Pod Autoscaler(HPA) in your EKS Kubernetes Cluster. In the meantime check other Kubernetes related articles available in our website.
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