Custom Resource Definitions (CRDs) in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Custom Resource Definition (CRD) in Kubernetes?

A CRD is a way to add your own custom objects to Kubernetes. It lets you define new resource types beyond the built-in ones, so you can manage your own data with Kubernetes tools.

beginner

How do you create a new custom resource type in Kubernetes?

You create a CRD YAML file that defines the new resource's name, version, and schema, then apply it with kubectl. This tells Kubernetes about your new resource type.

beginner

What command applies a CRD YAML file to the Kubernetes cluster?

kubectl apply -f applies the CRD to the cluster, registering the new custom resource type.

intermediate

Why use CRDs instead of ConfigMaps or Secrets for custom data?

CRDs let you create structured, typed resources with validation and versioning. ConfigMaps and Secrets are simpler key-value stores without schema or lifecycle management.

intermediate

What is the role of a controller with CRDs?

A controller watches custom resources and acts on changes. It helps automate tasks like creating pods or updating status based on the custom resource's state.

What does a Custom Resource Definition (CRD) allow you to do in Kubernetes?

A Upgrade Kubernetes versions

B Define new resource types

C Delete nodes automatically

D Monitor cluster health

CRDs let you define new resource types that Kubernetes can manage.

Which command is used to apply a CRD YAML file to a Kubernetes cluster?

A kubectl apply -f <file>

B kubectl create crd

C kubectl get crd

D kubectl delete crd

kubectl apply -f applies the CRD YAML to the cluster.

What is a key benefit of using CRDs over ConfigMaps for custom data?

A CRDs support schema validation

B ConfigMaps are encrypted by default

C CRDs cannot be versioned

D ConfigMaps allow custom resource types

CRDs support schema validation, making data structured and reliable.

What component typically watches CRDs to automate actions?

A Scheduler

B API Server

C Controller

D Kubelet

Controllers watch CRDs and automate responses to changes.

Which of these is NOT true about CRDs?

A They extend Kubernetes with new resource types

B They support versioning and validation

C They can be managed with kubectl

D They require writing Go code to use

You do not need to write Go code to use CRDs; you define them with YAML.

Explain what a Custom Resource Definition (CRD) is and why it is useful in Kubernetes.

Think about how Kubernetes can manage things beyond built-in resources.

Describe the steps to create and use a new custom resource in Kubernetes using a CRD.

Focus on YAML definition, applying it, and using the new resource.