Metrics Server installation in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Check Metrics Server pods status after installation

You installed Metrics Server in your Kubernetes cluster. What is the output of the command kubectl get pods -n kube-system -l k8s-app=metrics-server if the installation was successful and pods are running?

Kubernetes

kubectl get pods -n kube-system -l k8s-app=metrics-server

A Error from server (NotFound): pods "metrics-server" not found

B No resources found in kube-system namespace.

C

NAME                            READY   STATUS           RESTARTS   AGE
metrics-server-abcdef123-xyz12  0/1     CrashLoopBackOff 3          5m

D

NAME                            READY   STATUS    RESTARTS   AGE
metrics-server-abcdef123-xyz12  1/1     Running   0          5m

💡 Hint

Look for pods labeled with k8s-app=metrics-server in the kube-system namespace and check their status.

When Metrics Server is installed correctly, its pod should be in Running status with all containers ready.

🧠 Conceptual

intermediate

Purpose of Metrics Server in Kubernetes

What is the primary purpose of the Metrics Server in a Kubernetes cluster?

A To collect resource usage data like CPU and memory from nodes and pods for autoscaling and monitoring.

B To store persistent logs of all cluster events for auditing purposes.

C To manage network policies and firewall rules between pods.

D To schedule pods onto nodes based on resource availability.

💡 Hint

Think about what data autoscalers need to function.

Metrics Server collects resource usage metrics such as CPU and memory from nodes and pods, enabling features like Horizontal Pod Autoscaler.

❓ Troubleshoot

advanced

Diagnosing Metrics Server API access failure

After installing Metrics Server, you run kubectl top nodes but get the error: error: metrics API not available. Which of the following is the most likely cause?

A Metrics Server pod is not running or crashed.

B kubectl client version is outdated and incompatible.

C The kubelet service on nodes is disabled.

D The cluster has no nodes registered.

💡 Hint

Check the status of Metrics Server pods first.

If Metrics Server pods are not running, the metrics API will not be available, causing this error.

❓ Configuration

advanced

Correct flag to enable insecure TLS for Metrics Server

You want to deploy Metrics Server but your cluster uses self-signed certificates causing TLS errors. Which flag should you add to the Metrics Server deployment args to allow insecure TLS communication?

A --allow-insecure-connections

B --disable-tls-verification

C --kubelet-insecure-tls

D --skip-tls-check

💡 Hint

Look for the official flag documented for kubelet TLS issues.

The official flag to allow Metrics Server to skip TLS verification when connecting to kubelets is --kubelet-insecure-tls.

🔀 Workflow

expert

Order the steps to install Metrics Server correctly

Arrange the following steps in the correct order to install Metrics Server on a Kubernetes cluster:

A 3,1,2,4

B 1,2,3,4

C 1,3,2,4

D 2,1,3,4

💡 Hint

Think about the logical order: get files, apply, check pods, then test metrics.

First download the manifest, then apply it to create resources, check pods are running, and finally test metrics API.

Practice

1. What is the primary purpose of the Kubernetes Metrics Server?

easy

A. To schedule pods on specific nodes

B. To collect live CPU and memory usage data from cluster nodes and pods

C. To store persistent data for applications

D. To manage network policies between pods

Solution

1. Step 1: Understand Metrics Server role

   The Metrics Server collects resource usage data like CPU and memory from nodes and pods in the cluster.

2. Step 2: Differentiate from other components

   It does not manage network policies, store data, or schedule pods, which are handled by other Kubernetes components.

3. Final Answer:

   To collect live CPU and memory usage data from cluster nodes and pods -> Option B

4. Quick Check:

   Metrics Server = resource usage data collection [OK]

Hint: Metrics Server = live resource data collector [OK]

Common Mistakes:

• Confusing Metrics Server with network or storage components
• Thinking it schedules pods
• Assuming it stores persistent data

2. Which command correctly installs the Metrics Server in a Kubernetes cluster?

easy

A. kubectl run metrics-server --image=metrics-server:latest

B. kubectl create deployment metrics-server

C. kubectl install metrics-server

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

Solution

1. Step 1: Identify official installation method

   The Metrics Server is installed by applying the official components.yaml manifest from the Kubernetes SIGs GitHub repository using kubectl apply.

2. Step 2: Check command correctness

   Only kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml uses kubectl apply with the correct URL. Other options use incorrect commands or methods.

3. Final Answer:

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

4. Quick Check:

   Install Metrics Server = kubectl apply official manifest [OK]

Hint: Use kubectl apply with official components.yaml URL [OK]

Common Mistakes:

• Using kubectl create or run instead of apply
• Missing the full URL to the manifest
• Trying to install with a non-existent command

3. After installing Metrics Server, what is the expected output of kubectl top nodes?

medium

A. A list showing CPU and memory usage for each node

B. An error saying Metrics Server is not found

C. A list of pods running on each node

D. No output, command does nothing

Solution

1. Step 1: Understand kubectl top nodes command

   This command shows current CPU and memory usage metrics for each node in the cluster, provided Metrics Server is installed and working.

2. Step 2: Identify expected output

   With Metrics Server installed, it returns a table listing nodes with their CPU and memory usage. Errors or empty output indicate installation or connectivity issues.

3. Final Answer:

   A list showing CPU and memory usage for each node -> Option A

4. Quick Check:

   kubectl top nodes = node resource usage list [OK]

Hint: kubectl top nodes shows node CPU/memory usage [OK]

Common Mistakes:

• Expecting pod lists instead of metrics
• Assuming command fails after installation
• Confusing with other kubectl commands

4. You installed Metrics Server but kubectl top pods returns an error. What is the most likely cause?

medium

A. Metrics Server is not running or has permission issues

B. kubectl top pods command is deprecated

C. You need to restart the Kubernetes cluster

D. Pods do not have resource limits set

Solution

1. Step 1: Analyze error cause

   If kubectl top pods fails, it usually means Metrics Server is not running properly or lacks permissions to gather metrics.

2. Step 2: Rule out other options

   The command is not deprecated, cluster restart is rarely needed, and missing resource limits does not cause this error.

3. Final Answer:

   Metrics Server is not running or has permission issues -> Option A

4. Quick Check:

   kubectl top pods error = Metrics Server problem [OK]

Hint: Check Metrics Server pod status and permissions first [OK]

Common Mistakes:

• Assuming kubectl top pods is deprecated
• Restarting cluster unnecessarily
• Thinking resource limits cause command failure

5. You want to install Metrics Server but your cluster nodes use self-signed certificates causing TLS errors. What is the best way to fix this during installation?

hard

A. Disable TLS on all cluster nodes

B. Install Metrics Server without any changes; it will auto-fix TLS

C. Edit the Metrics Server deployment to add --kubelet-insecure-tls argument

D. Use a different monitoring tool that does not require TLS

Solution

1. Step 1: Identify TLS issue cause

   Self-signed certificates cause TLS verification errors when Metrics Server connects to kubelets.

2. Step 2: Apply correct fix

   Adding the --kubelet-insecure-tls flag to Metrics Server deployment disables strict TLS verification, allowing it to work with self-signed certs.

3. Step 3: Rule out unsafe or incorrect options

   Disabling TLS cluster-wide is unsafe, Metrics Server does not auto-fix TLS, and switching tools is unnecessary.

4. Final Answer:

   Edit the Metrics Server deployment to add --kubelet-insecure-tls argument -> Option C

5. Quick Check:

   Self-signed certs fix = add --kubelet-insecure-tls [OK]

Hint: Add --kubelet-insecure-tls flag for self-signed certs [OK]

Common Mistakes:

• Disabling TLS on nodes (unsafe)
• Expecting Metrics Server to auto-fix TLS
• Ignoring TLS errors and proceeding