Question 786 of 720
CKS Minimize Microservice Vulnerabilities Practice Question
An administrator deploys a Gatekeeper ConstraintTemplate with the following Rego policy:
package k8srequiredlabels deny[{"msg": msg}] { input.request.kind.kind == "Pod" not input.request.object.metadata.labels["security-tier"] msg := "Pod must have label 'security-tier'"
}
After creating the Constraint, a user creates a Pod without the 'security-tier' label. What is the expected behavior?
⚠ Common exam trap
The exam often tests the distinction between validating and mutating admission webhooks—candidates may mistakenly think Gatekeeper can auto-add labels (mutating behavior) or that it only logs violations (audit mode), but the Rego policy here uses 'deny' which causes immediate rejection.
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
✓
The pod creation is denied with a message
The Gatekeeper ConstraintTemplate defines a Rego policy that denies any Pod creation request that lacks the 'security-tier' label. When the user creates a Pod without this label, the admission webhook evaluates the policy and returns a denial message 'Pod must have label 'security-tier'', preventing the Pod from being created. Gatekeeper operates as a validating admission webhook, so it rejects the request before the object is persisted in etcd.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The pod is created and the label is automatically added
Why it's wrong here
Gatekeeper does not mutate resources unless a mutating webhook is configured.
- ✓
The pod creation is denied with a message
Why this is correct
Correct. The deny rule blocks admission and returns the message.
- ✗
Only the first pod without the label is denied; subsequent ones are allowed
Why it's wrong here
Gatekeeper evaluates every request independently; no such caching.
- ✗
The pod is created but logged as a violation
Why it's wrong here
Gatekeeper enforces admission by denying, not just logging.
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Last reviewed: Jul 4, 2026
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