Executing commands in Pods in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to execute a shell inside a pod named 'my-pod'.

Kubernetes

kubectl exec -it my-pod -- [1]

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

Astart

Brun

Cbash

Dopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using commands like 'run' or 'start' which are not shell commands.

Forgetting the '--' before the command.

The kubectl exec command runs a command inside a pod. To open a shell, you use bash.

2fill in blank

medium

Complete the command to run 'ls /app' inside a pod named 'web-server'.

Kubernetes

kubectl exec web-server -- [1] /app

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

Als

Bcd

Cpwd

Dcat

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cd' which changes directory but does not list files.

Using 'pwd' which shows current directory path.

The ls command lists files in a directory. Here, it lists files inside /app in the pod.

3fill in blank

hard

Fix the error in the command to run 'env' inside a pod named 'db-pod'.

Kubernetes

kubectl exec [1] -- env

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

Adb-pod

Bdb_pod

Cdb pod

Ddb-pod/

Attempts:

3 left

💡 Hint

Common Mistakes

Using underscores instead of dashes in pod names.

Including spaces or slashes in pod names.

Pod names cannot contain spaces or slashes. The correct pod name is db-pod.

4fill in blank

hard

Fill both blanks to correctly execute a command inside a pod named 'cache-pod' to print the working directory.

Kubernetes

kubectl exec [1] -- [2]

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

Acache-pod

Bpwd

Cls

Dbash

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ls' instead of 'pwd' to print the directory.

Using wrong pod names or extra characters.

The command pwd prints the current directory inside the pod named cache-pod.

5fill in blank

hard

Fill all three blanks to run a shell inside a pod named 'api-pod' and keep the session interactive.

Kubernetes

kubectl exec [1] [2] -- [3]

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

Aapi-pod

B-it

Cbash

D-i

Attempts:

3 left

💡 Hint

Common Mistakes

Using only '-i' without '-t' which may cause no terminal allocation.

Forgetting the '--' before the command.

The -it flags keep the session interactive and allocate a terminal. The command bash opens the shell inside the pod api-pod.

Practice

1. What is the primary purpose of the kubectl exec command in Kubernetes?

easy

A. To list all Pods in a namespace

B. To create a new Pod

C. To run commands inside a running Pod

D. To delete a Pod

Solution

1. Step 1: Understand the function of kubectl exec

   The kubectl exec command is used to execute commands inside a running Pod's container.

2. Step 2: Differentiate from other commands

   Creating, deleting, or listing Pods are done with other commands like kubectl create, kubectl delete, and kubectl get.

3. Final Answer:

   To run commands inside a running Pod -> Option C

4. Quick Check:

   kubectl exec runs commands inside Pods [OK]

Hint: Remember: exec means execute inside Pod [OK]

Common Mistakes:

• Confusing exec with create or delete commands
• Thinking exec lists Pods
• Using exec to start new Pods

2. Which of the following is the correct syntax to run the command ls /app inside a Pod named web-pod?

easy

A. kubectl exec web-pod ls /app

B. kubectl exec web-pod -- ls /app

C. kubectl exec -- web-pod ls /app

D. kubectl exec -c web-pod ls /app

Solution

1. Step 1: Identify correct command separator

   The -- separates the Pod name from the command to run inside the Pod.

2. Step 2: Apply syntax rules

   The correct syntax is kubectl exec [pod-name] -- [command], so kubectl exec web-pod -- ls /app is correct.

3. Final Answer:

   kubectl exec web-pod -- ls /app -> Option B

4. Quick Check:

   Use -- before command [OK]

Hint: Use double dash (--) before command [OK]

Common Mistakes:

• Omitting the -- separator
• Placing -- before Pod name
• Using -c without container name

3. Given a Pod named db-pod with two containers: mysql and backup, what is the output of this command?

kubectl exec db-pod -c backup -- echo Hello

medium

A. Pod not found

B. Error: container name required

C. No such container: backup

D. Hello

Solution

1. Step 1: Understand the command components

   The command runs echo Hello inside the backup container of the db-pod Pod.

2. Step 2: Predict the command output

   Since the container exists and the command is valid, it outputs Hello.

3. Final Answer:

   Hello -> Option D

4. Quick Check:

   Correct container specified with -c outputs command result [OK]

Hint: Use -c to specify container, output is command result [OK]

Common Mistakes:

• Not specifying container when multiple exist
• Using wrong container name
• Expecting Pod name as container

4. You run this command but get an error:

kubectl exec mypod ls /data

What is the most likely cause?

medium

A. Missing -- before the command

B. Pod mypod does not exist

C. The ls command is invalid

D. You need to specify the container with -c

Solution

1. Step 1: Check command syntax

   The command is missing the -- separator between Pod name and command.

2. Step 2: Understand effect of missing --

   Without --, kubectl treats ls as a Pod or option, causing an error.

3. Final Answer:

   Missing -- before the command -> Option A

4. Quick Check:

   Always use -- before command [OK]

Hint: Always put -- before command to avoid errors [OK]

Common Mistakes:

• Forgetting the -- separator
• Assuming container must be specified when only one exists
• Thinking command is invalid

5. You want to run cat /etc/config inside the app-container of Pod multi-pod which has three containers. Which command is correct?

hard

A. kubectl exec multi-pod -c app-container -- cat /etc/config

B. kubectl exec multi-pod cat /etc/config -c app-container

C. kubectl exec -c app-container multi-pod cat /etc/config

D. kubectl exec multi-pod -- -c app-container cat /etc/config

Solution

1. Step 1: Identify correct order of options

   The -c option specifying the container must come after the Pod name and before the -- separator.

2. Step 2: Confirm command separator usage

   The -- must separate the Pod/container specification from the command to run.

3. Step 3: Validate each option

   kubectl exec multi-pod -c app-container -- cat /etc/config correctly places -c app-container before -- and then the command cat /etc/config.

4. Final Answer:

   kubectl exec multi-pod -c app-container -- cat /etc/config -> Option A

5. Quick Check:

   -c before --, then command [OK]

Hint: Put -c before --, then command [OK]

Common Mistakes:

• Placing -c after the command
• Putting -- before -c
• Omitting -- separator