Label-based filtering with kubectl in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Filter pods by label with kubectl

You have several pods with labels: app=web and env=prod. Which command lists only pods with label app=web?

A kubectl get pods -l env=web

B kubectl get pods --filter app=web

C kubectl get pods -l app=web

D kubectl get pods --label-selector env=prod

💡 Hint

Use the -l or --selector flag to filter by label.

The -l flag filters pods by label. Option C correctly filters pods with label app=web. Option C uses an invalid flag. Option C filters by a different label. Option C filters by a label that does not exist.

💻 Command Output

intermediate

Filter pods with multiple labels

Which command lists pods with labels app=web AND env=prod?

A kubectl get pods -l app=web,env=prod

B kubectl get pods -l app=web; env=prod

C kubectl get pods --selector app=web env=prod

D kubectl get pods -l app=web env=prod

💡 Hint

Use commas to combine multiple labels in the selector.

Option A correctly uses commas to combine labels for AND filtering. Options B and C have invalid syntax. Option A uses a semicolon which is invalid.

❓ Troubleshoot

advanced

Why does this label filter return no pods?

You run kubectl get pods -l app=web env=prod but get no pods listed. Why?

A There are no pods with label <code>app=web</code>.

B The command syntax is incorrect; labels must be comma-separated with no spaces.

C The <code>kubectl</code> version does not support label filtering.

D The pods are in a different namespace.

💡 Hint

Check the label selector syntax carefully.

The command incorrectly separates labels with a space instead of a comma. The correct syntax is -l app=web,env=prod. Options A, C, and D may be possible but the question focuses on syntax error.

🧠 Conceptual

advanced

Label selector operators in kubectl

Which label selector operator filters pods that have label env but its value is NOT prod?

A kubectl get pods -l 'env!=prod'

B kubectl get pods -l 'env=prod'

C kubectl get pods -l 'env in (prod)'

D kubectl get pods -l 'env notin (prod)'

💡 Hint

Use the != operator to exclude a specific label value.

Option A uses the != operator to select pods where env label is not prod. Option A uses notin which requires parentheses and is valid but the question asks for the operator that filters pods with label env but value not prod using simple syntax. Option A selects only prod. Option A selects only prod.

✅ Best Practice

expert

Efficiently watch pods with label changes

You want to watch pods with label app=web and get notified immediately when pods are added or removed. Which command is best?

A kubectl logs -l app=web --follow

B kubectl describe pods -l app=web

C kubectl get pods -l app=web --watch-only

D kubectl get pods -l app=web --watch

💡 Hint

Use the watch flag to continuously monitor resource changes.

Option D uses --watch to continuously show pod changes matching the label. Option D only shows current details once. Option D is invalid flag. Option D follows logs from matching pods but does not watch for pods being added or removed.