Limit ranges for defaults in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the YAML to define a LimitRange with default CPU and memory limits.

Kubernetes

apiVersion: v1
kind: LimitRange
metadata:
  name: limits
spec:
  limits:
  - type: Container
    default:
      cpu: [1]
      memory: 512Mi

Drag options to blanks, or click blank then click option'

A500m

B1Gi

C100m

D256Mi

Attempts:

3 left

💡 Hint

Common Mistakes

Using memory units for CPU value

Omitting the 'm' suffix for CPU

The cpu default limit is set using millicores, so 100m means 0.1 CPU.

2fill in blank

medium

Complete the YAML to set default request values for CPU and memory in a LimitRange.

Kubernetes

apiVersion: v1
kind: LimitRange
metadata:
  name: limits
spec:
  limits:
  - type: Container
    defaultRequest:
      cpu: [1]
      memory: 256Mi

Drag options to blanks, or click blank then click option'

A200m

B1Gi

C100m

D512Mi

Attempts:

3 left

💡 Hint

Common Mistakes

Using memory units for CPU request

Setting request higher than limit

The defaultRequest for CPU is typically set in millicores, here 200m means 0.2 CPU.

3fill in blank

hard

Fix the error in the LimitRange YAML by completing the missing field for default CPU limit.

Kubernetes

apiVersion: v1
kind: LimitRange
metadata:
  name: limits
spec:
  limits:
  - type: Container
    default:
      cpu: [1]
      memory: 1Gi

Drag options to blanks, or click blank then click option'

A1000m

B1m

C1Gi

D100m

Attempts:

3 left

💡 Hint

Common Mistakes

Using memory units for CPU

Using too large or invalid CPU values

The CPU limit should be in millicores. 100m means 0.1 CPU, which is valid. 1Gi is a memory unit and invalid for CPU.

4fill in blank

hard

Fill both blanks to set default and defaultRequest memory limits in the LimitRange YAML.

Kubernetes

apiVersion: v1
kind: LimitRange
metadata:
  name: limits
spec:
  limits:
  - type: Container
    default:
      memory: [1]
    defaultRequest:
      memory: [2]

Drag options to blanks, or click blank then click option'

A512Mi

B256Mi

C1Gi

D128Mi

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping default and defaultRequest values

Using CPU units for memory

The default memory limit is usually higher than the defaultRequest. Here, 512Mi is the default limit and 256Mi is the default request.

5fill in blank

hard

Fill all three blanks to complete the LimitRange YAML with default CPU, defaultRequest CPU, and defaultRequest memory.

Kubernetes

apiVersion: v1
kind: LimitRange
metadata:
  name: limits
spec:
  limits:
  - type: Container
    default:
      cpu: [1]
    defaultRequest:
      cpu: [2]
      memory: [3]

Drag options to blanks, or click blank then click option'

A100m

B200m

C256Mi

D512Mi

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing CPU and memory units

Setting requests higher than limits

The default CPU limit is 100m, defaultRequest CPU is 200m, and defaultRequest memory is 256Mi. Requests are usually less than or equal to limits.

Practice

1. What is the main purpose of a LimitRange in a Kubernetes namespace?

easy

A. To schedule pods on specific nodes

B. To set default and maximum resource limits for containers in that namespace

C. To create network policies for pods

D. To manage persistent storage volumes

Solution

1. Step 1: Understand LimitRange role

   A LimitRange defines default, minimum, and maximum resource limits for containers in a namespace.

2. Step 2: Compare with other options

   Network policies, scheduling, and storage are managed by other Kubernetes resources, not LimitRange.

3. Final Answer:

   To set default and maximum resource limits for containers in that namespace -> Option B

4. Quick Check:

   LimitRange controls resource limits = C [OK]

Hint: LimitRange controls resource limits, not networking or storage [OK]

Common Mistakes:

• Confusing LimitRange with NetworkPolicy
• Thinking LimitRange schedules pods
• Assuming LimitRange manages storage

2. Which of the following is the correct YAML snippet to set a default CPU request of 100m using a LimitRange?

easy

A. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: cpu-default\nspec:\n limits:\n - default:\n cpu: 100m\n type: Container

B. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: cpu-default\nspec:\n limits:\n - defaultRequest:\n cpu: 100m\n type: Container

C. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: cpu-default\nspec:\n limits:\n - defaultLimit:\n cpu: 100m\n type: Container

D. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: cpu-default\nspec:\n limits:\n - defaultCpu:\n cpu: 100m\n type: Container

Solution

1. Step 1: Check LimitRange syntax for default

   The correct key to set default resource requests or limits is default under limits.

2. Step 2: Validate the YAML snippet

   apiVersion: v1\nkind: LimitRange\nmetadata:\n name: cpu-default\nspec:\n limits:\n - default:\n cpu: 100m\n type: Container uses default: with cpu: 100m correctly under limits and type: Container.

3. Final Answer:

   Option A is the correct YAML snippet -> Option A

4. Quick Check:

   Use default key for defaults in LimitRange [OK]

Hint: Use 'default' key under limits to set default resources [OK]

Common Mistakes:

• Using incorrect keys like defaultRequest or defaultLimit
• Misplacing keys outside limits array
• Wrong indentation in YAML

3. Given this LimitRange YAML applied in a namespace:

apiVersion: v1
kind: LimitRange
metadata:
  name: mem-default
spec:
  limits:
  - default:
      memory: 256Mi
    type: Container

What will be the memory request for a container without any memory request specified?

medium

A. No memory request will be set

B. Pod creation will fail due to missing memory request

C. Memory request will be unlimited

D. 256Mi memory request will be applied by default

Solution

1. Step 1: Understand default in LimitRange

   The default memory value sets the memory request if the container does not specify one.

2. Step 2: Apply to container without memory request

   Since the container has no memory request, Kubernetes applies the default 256Mi memory request from LimitRange.

3. Final Answer:

   256Mi memory request will be applied by default -> Option D

4. Quick Check:

   Default resource applies if container omits it [OK]

Hint: Default applies only if container omits resource request [OK]

Common Mistakes:

• Assuming no default means no request
• Thinking pod creation fails without explicit request
• Confusing default with max or min limits

4. You applied this LimitRange YAML:

apiVersion: v1
kind: LimitRange
metadata:
  name: cpu-limit
spec:
  limits:
  - max:
      cpu: 500m
    type: Container

Your pod container requests 600m CPU. What will happen?

medium

A. Pod will be created with 600m CPU request

B. Pod will ignore LimitRange and use 600m CPU

C. Pod creation will fail due to exceeding max CPU limit

D. Pod CPU request will be automatically reduced to 500m

Solution

1. Step 1: Understand max limit enforcement

   LimitRange max limits set the maximum allowed resource request or limit for containers.

2. Step 2: Check pod CPU request against max

   The pod requests 600m CPU, which exceeds the max 500m CPU set by LimitRange.

3. Step 3: Kubernetes behavior on violation

   Kubernetes rejects pod creation if resource requests exceed LimitRange max limits.

4. Final Answer:

   Pod creation will fail due to exceeding max CPU limit -> Option C

5. Quick Check:

   Exceeding max limit causes pod creation failure [OK]

Hint: Requests above max limit cause pod creation failure [OK]

Common Mistakes:

• Assuming Kubernetes auto-adjusts resource requests
• Thinking pod ignores LimitRange max limits
• Confusing max limit with default value

5. You want all containers in a namespace to have a default CPU request of 200m and a default memory request of 512Mi, but also want to ensure no container can request more than 1 CPU or 1Gi memory. Which LimitRange YAML snippet correctly enforces this?

hard

A. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: resource-limits\nspec:\n limits:\n - default:\n cpu: 200m\n memory: 512Mi\n max:\n cpu: 1\n memory: 1Gi\n type: Container

B. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: resource-limits\nspec:\n limits:\n - defaultRequest:\n cpu: 200m\n memory: 512Mi\n maxLimit:\n cpu: 1\n memory: 1Gi\n type: Container

C. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: resource-limits\nspec:\n limits:\n - defaultCpu:\n cpu: 200m\n memory: 512Mi\n maxCpu:\n cpu: 1\n memory: 1Gi\n type: Container

D. apiVersion: v1\nkind: LimitRange\nmetadata:\n name: resource-limits\nspec:\n limits:\n - default:\n cpu: 200m\n memory: 512Mi\n maxRequest:\n cpu: 1\n memory: 1Gi\n type: Container

Solution

1. Step 1: Identify correct keys for defaults and max

   The correct keys are default for default requests and max for maximum allowed resources under limits.

2. Step 2: Validate YAML structure

   apiVersion: v1\nkind: LimitRange\nmetadata:\n name: resource-limits\nspec:\n limits:\n - default:\n cpu: 200m\n memory: 512Mi\n max:\n cpu: 1\n memory: 1Gi\n type: Container correctly uses default and max keys with proper resource names and type: Container.

3. Step 3: Check other options for invalid keys

   Options B, C, and D use invalid keys like defaultRequest, maxLimit, defaultCpu, or maxRequest which are not valid in LimitRange spec.

4. Final Answer:

   Option A correctly enforces default and max resource limits -> Option A

5. Quick Check:

   Use 'default' and 'max' keys for defaults and max limits [OK]

Hint: Use 'default' and 'max' keys under limits for defaults and max limits [OK]

Common Mistakes:

• Using invalid keys like defaultRequest or maxLimit
• Mixing up default and max keys
• Incorrect YAML indentation or structure