kubectl exec for container access in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of kubectl exec with command

What is the output of this command if the pod myapp-pod has a container named app-container running a Linux shell?

kubectl exec myapp-pod -c app-container -- ls /tmp

A Returns an error: container app-container not found

B Shows the logs of the container app-container

C Starts an interactive shell session inside the container

D Lists files and directories inside /tmp of the container

💡 Hint

The command runs 'ls /tmp' inside the specified container.

The 'kubectl exec' command runs the given command inside the container. Here, it lists the contents of /tmp directory inside the container named 'app-container'.

💻 Command Output

intermediate

Error when container name is missing

What error will you get if you run this command on a pod with multiple containers?

kubectl exec mypod -- ls /

A Error: a container name must be specified for pod mypod, choose one of: [container1 container2]

B Lists root directory contents of the first container automatically

C Syntax error: missing container name

D Command runs successfully on all containers

💡 Hint

Pods with multiple containers require specifying which container to exec into.

When a pod has multiple containers, kubectl requires the container name to be specified with -c or --container. Otherwise, it returns an error asking to specify the container.

🔀 Workflow

advanced

Correct command to start an interactive shell inside a container

Which command correctly starts an interactive bash shell inside the container named web in pod frontend-pod?

A kubectl exec -it frontend-pod -c web -- /bin/bash

B kubectl exec frontend-pod -c web /bin/bash -i -t

C kubectl exec frontend-pod -c web --interactive --tty /bin/bash

D kubectl exec frontend-pod -c web -- bash -it

💡 Hint

Use -i and -t flags before pod name for interactive terminal.

The correct syntax is 'kubectl exec -it podname -c containername -- command'. Flags -i and -t enable interactive terminal. The command follows after '--'.

❓ Troubleshoot

advanced

Troubleshooting kubectl exec permission denied error

You run kubectl exec mypod -- cat /etc/shadow and get a permission denied error. What is the most likely reason?

A The pod is not running

B kubectl exec requires root privileges on the host machine

C The user inside the container does not have permission to read /etc/shadow

D The container image does not have /etc/shadow file

💡 Hint

File /etc/shadow is usually restricted to root user inside Linux.

The /etc/shadow file contains sensitive password info and is readable only by root or privileged users inside the container. Permission denied means the current user lacks rights.

✅ Best Practice

expert

Best practice for running commands inside containers with kubectl exec

Which practice is best when using kubectl exec to run commands inside containers in production?

A Run kubectl exec commands as root user inside containers for full access

B Always specify the container name with -c to avoid ambiguity

C Use kubectl exec without -it flags to avoid interactive sessions

D Modify container images to include debugging tools for exec commands

💡 Hint

Pods often have multiple containers; specifying container avoids mistakes.

Specifying the container name with -c ensures the command runs in the intended container, preventing errors or unintended effects. Running as root or modifying images can cause security risks.