- A
Use a Gatekeeper Constraint that denies pods with readOnlyRootFilesystem not set to true, but add an exception label on the specific deployment's namespace or pod, and modify the Constraint to skip pods with that label
This allows fine-grained, policy-based enforcement with exceptions.
- B
Set a default readOnlyRootFilesystem: true via a mutating webhook, and then manually patch the specific deployment after creation
Why wrong: This is error-prone and not scalable.
- C
Modify the PodSecurityPolicy to allow readOnlyRootFilesystem: false for the specific deployment's service account
Why wrong: PodSecurityPolicy is deprecated and does not support per-pod exceptions easily.
- D
Set readOnlyRootFilesystem: true in the deployment's pod template and add an emptyDir volume for the temporary directory
Why wrong: This does not enforce the read-only root on other pods.
Enforce Read-Only Root Filesystem with Exception Using Gatekeeper
This CKS practice question tests your understanding of minimize microservice vulnerabilities. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An admin wants to enforce that all pods in a namespace use a read-only root filesystem except for a specific deployment that needs to write to a temporary directory. Which approach best meets this requirement?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use a Gatekeeper Constraint that denies pods with readOnlyRootFilesystem not set to true, but add an exception label on the specific deployment's namespace or pod, and modify the Constraint to skip pods with that label
Option A is correct because Gatekeeper (OPA/Gatekeeper) allows you to define a Constraint that denies pods without `readOnlyRootFilesystem: true`, and you can add an exception label on the specific deployment's pod template. By modifying the Constraint to skip pods with that label (using a `labelSelector` or `excludedNamespaces` in the Constraint's spec), you enforce the policy for all pods except the exempted deployment, meeting the requirement without manual patching or legacy PSPs.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use a Gatekeeper Constraint that denies pods with readOnlyRootFilesystem not set to true, but add an exception label on the specific deployment's namespace or pod, and modify the Constraint to skip pods with that label
Why this is correct
This allows fine-grained, policy-based enforcement with exceptions.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set a default readOnlyRootFilesystem: true via a mutating webhook, and then manually patch the specific deployment after creation
Why it's wrong here
This is error-prone and not scalable.
- ✗
Modify the PodSecurityPolicy to allow readOnlyRootFilesystem: false for the specific deployment's service account
Why it's wrong here
PodSecurityPolicy is deprecated and does not support per-pod exceptions easily.
- ✗
Set readOnlyRootFilesystem: true in the deployment's pod template and add an emptyDir volume for the temporary directory
Why it's wrong here
This does not enforce the read-only root on other pods.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between mutating webhooks (which can set defaults but require careful exception handling) and validating webhooks like Gatekeeper (which can enforce policies with label-based exceptions), leading candidates to choose the simpler but less robust mutating approach.
Detailed technical explanation
How to think about this question
Gatekeeper uses OPA Constraint Templates and Constraints to enforce policies via admission webhooks. The `readOnlyRootFilesystem` field in the Pod Security Context is a boolean that, when `true`, makes the container's filesystem read-only except for volumes mounted with write access. In a real-world scenario, you might use a `labelSelector` in the Constraint's `match` block to exclude pods with a specific label (e.g., `exempt: "true"`), or use `excludedNamespaces` to skip an entire namespace, ensuring the exception is declarative and version-controlled.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Minimize Microservice Vulnerabilities — study guide chapter
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a Gatekeeper Constraint that denies pods with readOnlyRootFilesystem not set to true, but add an exception label on the specific deployment's namespace or pod, and modify the Constraint to skip pods with that label — Option A is correct because Gatekeeper (OPA/Gatekeeper) allows you to define a Constraint that denies pods without `readOnlyRootFilesystem: true`, and you can add an exception label on the specific deployment's pod template. By modifying the Constraint to skip pods with that label (using a `labelSelector` or `excludedNamespaces` in the Constraint's spec), you enforce the policy for all pods except the exempted deployment, meeting the requirement without manual patching or legacy PSPs.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jul 4, 2026
This CKS practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKS exam.
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