Pod Disruption Budgets in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Pod Disruption Budget (PDB) in Kubernetes?

A Pod Disruption Budget is a Kubernetes resource that limits the number of pods of a service that can be voluntarily disrupted at the same time, ensuring availability during maintenance or upgrades.

beginner

Which field in a Pod Disruption Budget specifies how many pods can be unavailable during voluntary disruptions?

The maxUnavailable field sets the maximum number or percentage of pods that can be unavailable during voluntary disruptions.

intermediate

What is the difference between voluntary and involuntary disruptions in Kubernetes?

Voluntary disruptions are planned actions like node draining or pod eviction. Involuntary disruptions are unexpected failures like node crashes. PDBs only control voluntary disruptions.

intermediate

How does Kubernetes behave if a Pod Disruption Budget is violated during a voluntary disruption?

Kubernetes will block the voluntary disruption if it would cause the number of available pods to fall below the PDB's allowed threshold, protecting service availability.

beginner

Show a simple YAML snippet of a Pod Disruption Budget that allows at most 1 pod to be unavailable.

apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: example-pdb spec: maxUnavailable: 1 selector: matchLabels: app: myapp

What does a Pod Disruption Budget control in Kubernetes?

A The CPU usage of pods

B The total number of pods in a cluster

C The number of pods that can be voluntarily disrupted at once

D The network bandwidth of pods

A Pod Disruption Budget limits voluntary disruptions to maintain availability.

Which of these is NOT controlled by a Pod Disruption Budget?

A Unexpected node crashes

B Node draining disruptions

C Voluntary pod evictions

D Rolling updates

PDBs do not control involuntary disruptions like node crashes.

In a PDB, what does setting maxUnavailable: 2 mean?

A At most 2 pods can be unavailable during voluntary disruptions

B Exactly 2 pods must be unavailable

C No pods can be disrupted

D 2 pods will be restarted automatically

maxUnavailable sets the maximum number of pods allowed to be down during voluntary disruptions.

If a PDB is violated, what happens when you try to drain a node?

A The node drains immediately ignoring the PDB

B The drain command is blocked until pods are available

C The pods are deleted forcibly

D Nothing happens, PDBs are only informational

Kubernetes blocks voluntary disruptions that violate the PDB to protect availability.

Which selector does a Pod Disruption Budget use to identify pods it protects?

A Service selector

B Node selector

C Namespace selector

D Label selector

PDBs use label selectors to match the pods they protect.

Explain what a Pod Disruption Budget is and why it is important in Kubernetes.

Think about how Kubernetes manages pod availability during maintenance.

Describe how you would create a Pod Disruption Budget to allow only one pod to be disrupted at a time for an app labeled 'webapp'.

Focus on the key fields in the PDB YAML.