Linkerd as lightweight alternative in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to install Linkerd CLI using curl.

Kubernetes

curl -sL https://run.linkerd.io/install | [1]

Drag options to blanks, or click blank then click option'

Abash

Bsh

Cpython

Dzsh

Attempts:

3 left

💡 Hint

Common Mistakes

Using python or zsh instead of sh causes errors.

The Linkerd CLI installation script is run using sh after downloading with curl.

2fill in blank

medium

Complete the command to check if your Kubernetes cluster is ready for Linkerd installation.

Kubernetes

linkerd [1]

Drag options to blanks, or click blank then click option'

Ainstall

Bversion

Ccheck

Ddashboard

Attempts:

3 left

💡 Hint

Common Mistakes

Using install runs installation, not a readiness check.

The linkerd check command verifies if the cluster meets requirements for Linkerd.

3fill in blank

hard

Fix the error in the command to install Linkerd control plane in Kubernetes.

Kubernetes

linkerd install | kubectl [1] -f -

Drag options to blanks, or click blank then click option'

Aget

Bcreate

Cdelete

Dapply

Attempts:

3 left

💡 Hint

Common Mistakes

Using create fails if resources exist.

Using delete removes resources.

The correct command to apply the Linkerd control plane manifest is kubectl apply -f -.

4fill in blank

hard

Fill both blanks to inject Linkerd proxy into a deployment manifest.

Kubernetes

kubectl [1] deploy -n my-namespace -o yaml | linkerd [2] - | kubectl apply -f -

Drag options to blanks, or click blank then click option'

Aget

Binject

Cdelete

Ddescribe

Attempts:

3 left

💡 Hint

Common Mistakes

Using apply instead of get to fetch manifest.

Using delete or describe incorrectly.

First, get the deployment manifest, then inject Linkerd proxy using linkerd inject.

5fill in blank

hard

Fill all three blanks to check the status of Linkerd pods in the control plane namespace.

Kubernetes

kubectl -n [1] get pods -l [2]=linkerd -o [3]

Drag options to blanks, or click blank then click option'

Alinkerd

Bapp

Cwide

Ddefault

Attempts:

3 left

💡 Hint

Common Mistakes

Using default namespace instead of linkerd.

Using wrong label key or output format.

The Linkerd control plane runs in the linkerd namespace. Pods are labeled with app=linkerd. The -o wide option shows detailed pod info.

Practice

1. What is the main advantage of using Linkerd as a service mesh in Kubernetes?

easy

A. It replaces Kubernetes networking completely

B. It requires complex setup and high resource usage

C. It only works with virtual machines, not containers

D. It is lightweight and uses fewer resources

Solution

1. Step 1: Understand Linkerd's design goal

   Linkerd is designed to be a lightweight service mesh that adds security and observability without heavy resource use.

2. Step 2: Compare options with Linkerd's features

   Options B, C, and D describe incorrect or unrelated features. Linkerd is easy to install and uses fewer resources.

3. Final Answer:

   It is lightweight and uses fewer resources -> Option D

4. Quick Check:

   Lightweight = It is lightweight and uses fewer resources [OK]

Hint: Linkerd is known for being simple and light [OK]

Common Mistakes:

• Thinking Linkerd is complex to install
• Confusing Linkerd with full Kubernetes replacement
• Assuming it only works outside containers

2. Which command is used to add Linkerd's proxy to your Kubernetes application pods?

easy

A. linkerd inject

B. linkerd install

C. kubectl apply

D. kubectl expose

Solution

1. Step 1: Identify the command for proxy injection

   The linkerd inject command adds the Linkerd proxy sidecar to your app pods.

2. Step 2: Differentiate from other commands

   linkerd install sets up Linkerd control plane, kubectl apply applies configs, and kubectl expose creates services.

3. Final Answer:

   linkerd inject -> Option A

4. Quick Check:

   Proxy injection = linkerd inject [OK]

Hint: Inject adds proxy; install sets up control plane [OK]

Common Mistakes:

• Using linkerd install to inject proxies
• Confusing kubectl expose with proxy injection
• Skipping inject step after install

3. What is the output of this command sequence?

linkerd install | kubectl apply -f -
kubectl get pods -n linkerd

A) Shows error: command not found B) Injects proxy into app pods C) Deletes Linkerd namespace D) Installs Linkerd control plane and lists its pods

medium

A. Shows error: command not found

B. Injects proxy into app pods

C. Installs Linkerd control plane and lists its pods

D. Deletes Linkerd namespace

Solution

1. Step 1: Understand the command sequence

   linkerd install outputs YAML to install Linkerd control plane; piping it to kubectl apply -f - applies it to the cluster.

2. Step 2: Check the second command

   kubectl get pods -n linkerd lists pods in the Linkerd namespace, showing control plane pods running.

3. Final Answer:

   Installs Linkerd control plane and lists its pods -> Option C

4. Quick Check:

   Install + list pods = Installs Linkerd control plane and lists its pods [OK]

Hint: Install outputs YAML; apply deploys it; get pods shows status [OK]

Common Mistakes:

• Thinking inject happens with install
• Assuming namespace is deleted
• Expecting error without Linkerd installed

4. You ran linkerd inject deployment.yaml | kubectl apply -f - but your pods do not show the Linkerd proxy. What is the likely issue?

medium

A. kubectl apply command is incorrect

B. The Linkerd control plane is not installed

C. The deployment.yaml file is empty

D. Linkerd does not support proxy injection

Solution

1. Step 1: Check prerequisites for proxy injection

   Proxy injection requires the Linkerd control plane to be installed and running in the cluster.

2. Step 2: Analyze other options

   An empty deployment file would cause errors, incorrect kubectl apply syntax would fail, and Linkerd does support proxy injection.

3. Final Answer:

   The Linkerd control plane is not installed -> Option B

4. Quick Check:

   Proxy injection needs control plane installed [OK]

Hint: Proxy injection fails if control plane missing [OK]

Common Mistakes:

• Ignoring control plane installation
• Assuming deployment file is always correct
• Thinking kubectl apply syntax is wrong

5. You want to deploy a small Kubernetes app with minimal overhead but still want observability and security features. Which approach best uses Linkerd as a lightweight alternative?

hard

A. Install Linkerd control plane, then inject proxies into app pods using linkerd inject

B. Replace Kubernetes networking with Linkerd and disable proxies

C. Use Linkerd only on some nodes and skip installation on others

D. Manually add proxies to pods without using Linkerd commands

Solution

1. Step 1: Identify the correct lightweight setup

   Linkerd's lightweight approach is to install its control plane and inject proxies into app pods to add features with minimal resource use.

2. Step 2: Evaluate other options

   Replacing Kubernetes networking is not supported, partial node installation is not standard, and manual proxy addition is error-prone and not recommended.

3. Final Answer:

   Install Linkerd control plane, then inject proxies into app pods using linkerd inject -> Option A

4. Quick Check:

   Install + inject = lightweight Linkerd use [OK]

Hint: Install control plane, then inject proxies for lightweight setup [OK]

Common Mistakes:

• Trying to replace Kubernetes networking
• Skipping control plane installation
• Manually modifying pods without Linkerd tools