Disruption budgets limit supported voluntary evictions for eligible workloads. They do not prevent every failure or ensure sufficient spare capacity.
Before you start
You should understand Pods, Deployments and Services. Read desired configuration separately from observed cluster state. Use a development cluster when trying changes, and inspect events and status rather than assuming that an accepted manifest means the workload is ready to serve traffic.
The practical goal is to reason through this situation: A maintenance drain may wait when evicting another replica would violate the budget. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Distinguish voluntary disruption
Maintenance eviction differs from crashes or node failure.
Step 2: Align replicas and availability
The budget must permit necessary maintenance under sufficient capacity.
Step 3: Test drain behavior
An impossible requirement can stall node maintenance indefinitely.
Worked scenario
A maintenance drain may wait when evicting another replica would violate the budget.
A single-replica workload requiring that its only replica remain available cannot permit its voluntary eviction under that budget. Add suitable replication or revise the availability policy. A disruption budget does not prevent the node from failing unexpectedly, so resilience also needs capacity and application behavior.
Common mistake
An impossible budget can block routine node maintenance.
Verify the behavior
Rehearse maintenance drain and separately test unplanned replica failure.
Interview exercise
Prepare a maintenance policy.
Answer and reasoning
Align replica count, availability requirements and capacity, and distinguish voluntary disruption from crashes or infrastructure failure.
Continue learning
Compare the scenario with the Kubernetes interview questions and test your understanding with the Kubernetes MCQs. For terminology and implementation details, consult the reference material.