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Kubernetesdevops~10 mins

Custom Resource Definitions (CRDs) in Kubernetes - Interactive Code Practice

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Test this pattern10 questions across easy, medium, and hard to know if this pattern is strong
Practice - 5 Tasks
Answer the questions below
1fill in blank
easy

Complete the code to specify the API version for a CRD manifest.

Kubernetes
apiVersion: [1]
Drag options to blanks, or click blank then click option'
Aapiextensions.k8s.io/v1
Bv1
Capps/v1
Dbatch/v1
Attempts:
3 left
💡 Hint
Common Mistakes
Using 'v1' alone without the API group.
Using 'apps/v1' which is for deployments.
Using 'batch/v1' which is for jobs.
2fill in blank
medium

Complete the code to define the kind of the custom resource in the CRD manifest.

Kubernetes
kind: [1]
Drag options to blanks, or click blank then click option'
AService
BCustomResourceDefinition
CDeployment
DPod
Attempts:
3 left
💡 Hint
Common Mistakes
Using 'Deployment' or 'Service' which are standard Kubernetes resources.
Using 'Pod' which is a basic workload resource.
3fill in blank
hard

Fix the error in the CRD spec by completing the missing field for the resource names.

Kubernetes
spec:
  names:
    plural: [1]
Drag options to blanks, or click blank then click option'
AMyResources
BMyResource
Cmyresource
Dmyresources
Attempts:
3 left
💡 Hint
Common Mistakes
Using singular form instead of plural.
Using capital letters in the plural field.
4fill in blank
hard

Fill both blanks to define the scope and the kind of the custom resource in the CRD spec.

Kubernetes
spec:
  scope: [1]
  names:
    kind: [2]
Drag options to blanks, or click blank then click option'
ANamespaced
BCluster
CMyResource
DMyResources
Attempts:
3 left
💡 Hint
Common Mistakes
Mixing up scope values.
Using plural form for kind.
5fill in blank
hard

Fill all three blanks to complete the CRD version definition with name, served, and storage fields.

Kubernetes
spec:
  versions:
  - name: [1]
    served: [2]
    storage: [3]
Drag options to blanks, or click blank then click option'
Av1alpha1
Btrue
Cfalse
Dv1
Attempts:
3 left
💡 Hint
Common Mistakes
Using alpha versions for production CRDs.
Setting storage to false for the main version.

Practice

(1/5)
1. What is the main purpose of a Custom Resource Definition (CRD) in Kubernetes?
easy
A. To add new resource types to Kubernetes that are not built-in
B. To update the Kubernetes version automatically
C. To manage user permissions in Kubernetes
D. To monitor cluster health and performance

Solution

  1. Step 1: Understand what CRDs do

    CRDs allow users to create their own resource types beyond the default Kubernetes resources.

  2. Step 2: Compare options

    Automatic version updates, user permissions (RBAC), and cluster monitoring are separate Kubernetes features unrelated to CRDs.

  3. Final Answer:

    To add new resource types to Kubernetes that are not built-in -> Option A

  4. Quick Check:

    CRDs = add custom resource types [OK]
Hint: CRDs = add your own resource types [OK]
Common Mistakes:
  • Confusing CRDs with RBAC for permissions
  • Thinking CRDs update Kubernetes versions
  • Assuming CRDs monitor cluster health
2. Which of the following is the correct YAML key to define the API version for a CRD?
easy
A. version
B. api_version
C. apiVersion
D. apiVer

Solution

  1. Step 1: Recall Kubernetes YAML syntax

    Kubernetes uses camelCase keys like apiVersion to specify API versions.

  2. Step 2: Check other options

    version, api_version, and apiVer use incorrect formats not recognized by Kubernetes.

  3. Final Answer:

    apiVersion -> Option C

  4. Quick Check:

    Correct YAML key = apiVersion [OK]
Hint: Use camelCase keys like apiVersion in Kubernetes YAML [OK]
Common Mistakes:
  • Using underscores instead of camelCase
  • Using incomplete or shortened keys
  • Confusing version with apiVersion
3. Given this CRD snippet, what is the scope of the custom resource? 
spec:
  scope: Namespaced
  group: example.com
  names:
    kind: Widget
    plural: widgets
medium
A. Cluster-wide resource available in all namespaces
B. Resource limited to a specific namespace
C. Resource only available in the default namespace
D. Resource scoped to nodes

Solution

  1. Step 1: Read the scope field

    The scope is set to Namespaced, meaning the resource exists within namespaces.

  2. Step 2: Understand scope meanings

    Namespaced means the resource is limited to a specific namespace, not cluster-wide or node-scoped.

  3. Final Answer:

    Resource limited to a specific namespace -> Option B

  4. Quick Check:

    scope Namespaced = namespace-limited resource [OK]
Hint: scope: Namespaced means resource lives inside namespaces [OK]
Common Mistakes:
  • Confusing Namespaced with Cluster scope
  • Assuming default namespace only
  • Thinking scope relates to nodes
4. You applied a CRD YAML but get an error: "unknown field 'kindd'". What is the most likely cause?
medium
A. Typo in the YAML key 'kindd' instead of 'kind'
B. Missing apiVersion field
C. CRD name is not unique
D. Cluster role permissions missing

Solution

  1. Step 1: Analyze the error message

    The error says "unknown field 'kindd'", indicating a typo in the YAML key.

  2. Step 2: Identify the correct key

    The correct key is kind, so kindd is a misspelling causing the error.

  3. Final Answer:

    Typo in the YAML key 'kindd' instead of 'kind' -> Option A

  4. Quick Check:

    YAML key typos cause unknown field errors [OK]
Hint: Check YAML keys carefully for typos [OK]
Common Mistakes:
  • Ignoring spelling errors in YAML keys
  • Assuming missing fields cause unknown field errors
  • Blaming permissions for syntax errors
5. You want to create a CRD for a resource named Gadget that is cluster-scoped and has a plural name gadgets. Which YAML snippet correctly defines this?
hard
A. spec: group: example.com scope: Cluster names: kind: Gadget plural: gadget
B. spec: group: example.com scope: Namespaced names: kind: Gadget plural: gadgets
C. spec: group: example.com scope: Cluster names: kind: gadget plural: gadget
D. spec: group: example.com scope: Cluster names: kind: Gadget plural: gadgets

Solution

  1. Step 1: Check scope value

    The resource must be cluster-scoped, so scope: Cluster is correct.

  2. Step 2: Verify kind and plural names

    kind should be capitalized as Gadget and plural should be gadgets (plural lowercase).

  3. Step 3: Compare options

    The snippet with scope: Cluster, kind: Gadget, plural: gadgets matches all requirements. Snippets with scope: Namespaced, lowercase kind: gadget, or singular plural: gadget are incorrect.

  4. Final Answer:

    spec: group: example.com scope: Cluster names: kind: Gadget plural: gadgets -> Option D

  5. Quick Check:

    Cluster scope + correct kind/plural = spec: group: example.com scope: Cluster names: kind: Gadget plural: gadgets [OK]
Hint: Cluster scope means scope: Cluster; kind capitalized, plural lowercase [OK]
Common Mistakes:
  • Using Namespaced instead of Cluster scope
  • Incorrect casing for kind or plural
  • Using singular for plural name