The Metrics Server is a scalable, efficient source of container resource metrics for Kubernetes built-in autoscaling pipelines. It collects resource usage data from the Kubelet on each node and provides aggregated metrics through the Kubernetes API.

• Metrics Server: A cluster-wide aggregator of resource usage data.
• Kubelet: An agent that runs on each node in the cluster and reports resource usage.
• Resource Metrics API: An API provided by the Metrics Server to access resource usage data.

• Autoscaling: Metrics Server is essential for Horizontal Pod Autoscaler (HPA) and Vertical Pod Autoscaler (VPA).
• Monitoring: Provides insights into resource usage for better monitoring and management.
• Efficiency: Lightweight and designed to handle large clusters efficiently.

• A running Kubernetes cluster.
• kubectl command-line tool configured to interact with your cluster.

1. Download the Metrics Server manifest:

   kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
   

2. Verify the installation:

   kubectl get deployment metrics-server -n kube-system
   

3. Check the Metrics Server logs:

   kubectl logs -n kube-system deployment/metrics-server
   

You can access the metrics using the kubectl top command.

• View node metrics:

  kubectl top nodes
  

• View pod metrics:

  kubectl top pods --all-namespaces
  

1. Install Metrics Server:

   • Follow the installation steps provided above.

2. Verify the installation:

   • Ensure the Metrics Server is running by checking the deployment status and logs.

3. Access node metrics:

   • Use kubectl top nodes to view the resource usage of nodes.

4. Access pod metrics:

   • Use kubectl top pods --all-namespaces to view the resource usage of pods.

1. Install Metrics Server:

   kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
   

2. Verify the installation:

   kubectl get deployment metrics-server -n kube-system
   kubectl logs -n kube-system deployment/metrics-server
   

3. Access node metrics:

   kubectl top nodes
   

4. Access pod metrics:

   kubectl top pods --all-namespaces
   

• Metrics Server not collecting data: Ensure that the Metrics Server has the necessary permissions and that the Kubelet is configured correctly.
• Resource usage not displayed: It may take a few minutes for the Metrics Server to start collecting and displaying data after installation.
• Cluster size: Metrics Server is designed to handle large clusters, but ensure your cluster resources are sufficient to support it.

The Metrics Server is a crucial component for monitoring and autoscaling in Kubernetes. By providing resource usage metrics, it enables efficient management and scaling of applications. In this section, you learned how to install, verify, and use the Metrics Server to access node and pod metrics. This knowledge is foundational for advanced topics like autoscaling and performance tuning.