Memory requests and limits in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a memory request of 256Mi for the container.

Kubernetes

resources:
  requests:
    memory: [1]

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

A256MB

B256Mi

C256

D256Kb

Attempts:

3 left

💡 Hint

Common Mistakes

Using '256MB' instead of '256Mi'.

Omitting units like 'Mi'.

The correct memory request format in Kubernetes uses units like Mi (mebibytes). '256Mi' means 256 mebibytes.

2fill in blank

medium

Complete the code to set a memory limit of 512Mi for the container.

Kubernetes

resources:
  limits:
    memory: [1]

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

A512Mi

B512MB

C512

D512Kb

Attempts:

3 left

💡 Hint

Common Mistakes

Using '512MB' which is not recognized.

Leaving out units.

Memory limits require units like 'Mi' for mebibytes. '512Mi' is the correct format.

3fill in blank

hard

Fix the error in the memory request value to use the correct unit.

Kubernetes

resources:
  requests:
    memory: [1]

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

A128

B128MB

C128Mi

D128Kb

Attempts:

3 left

💡 Hint

Common Mistakes

Using '128MB' instead of '128Mi'.

Omitting units.

The correct memory request must use 'Mi' units. '128Mi' is valid, '128MB' is not.

4fill in blank

hard

Fill both blanks to set memory requests and limits correctly.

Kubernetes

resources:
  requests:
    memory: [1]
  limits:
    memory: [2]

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

A256Mi

B512Mi

C256MB

D512MB

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'MB' units.

Setting limits smaller than requests.

Memory requests and limits must use 'Mi' units. '256Mi' for requests and '512Mi' for limits is correct.

5fill in blank

hard

Fill all three blanks to define a container with memory requests and limits.

Kubernetes

containers:
- name: app
  resources:
    requests:
      memory: [1]
    limits:
      memory: [2]
  image: myapp:latest
  env:
    - name: ENV_VAR
      value: [3]

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

A128Mi

B256Mi

C"production"

D"dev"

Attempts:

3 left

💡 Hint

Common Mistakes

Using memory units incorrectly.

Not quoting environment variable values.

The container requests 128Mi memory, limits 256Mi, and sets environment variable to 'production'.

Practice

1. What does the memory request specify in a Kubernetes pod configuration?

easy

A. The total memory available on the node

B. The maximum amount of memory the container can use

C. The amount of memory the container has currently used

D. The minimum amount of memory guaranteed for the container

Solution

1. Step 1: Understand memory request meaning

   Memory request is the minimum memory Kubernetes guarantees to a container so it can run without being killed due to lack of memory.

2. Step 2: Differentiate from memory limit

   Memory limit is the max memory allowed, not the minimum guaranteed.

3. Final Answer:

   The minimum amount of memory guaranteed for the container -> Option D

4. Quick Check:

   Memory request = minimum guaranteed memory [OK]

Hint: Requests = minimum guaranteed memory, limits = max allowed [OK]

Common Mistakes:

• Confusing memory request with memory limit
• Thinking request is the max memory
• Assuming request is current usage

2. Which of the following is the correct way to specify memory requests and limits in a Kubernetes pod YAML?

easy

A. resources:
requests:
memory: "256Mi"
limits:
memory: "512Mi"

B. resources:
memory:
request: 256
limit: 512

C. memory:
requests: 256Mi
limits: 512Mi

D. resources:
requests:
mem: 256Mi
limits:
mem: 512Mi

Solution

1. Step 1: Recall correct YAML structure for resources

   In Kubernetes, memory requests and limits are under resources.requests.memory and resources.limits.memory with values as strings including units like "Mi".

2. Step 2: Check each option for syntax correctness

   resources: requests: memory: "256Mi" limits: memory: "512Mi" matches the correct syntax. Options A, B, and C use wrong keys or structure.

3. Final Answer:

   resources: requests: memory: "256Mi" limits: memory: "512Mi" -> Option A

4. Quick Check:

   Correct YAML keys and units = resources: requests: memory: "256Mi" limits: memory: "512Mi" [OK]

Hint: Use resources.requests.memory and resources.limits.memory keys [OK]

Common Mistakes:

• Using wrong keys like 'mem' or 'memory' outside resources
• Omitting quotes or units for memory values
• Swapping 'request' and 'requests'

3. Given this pod spec snippet:

resources:
  requests:
    memory: "128Mi"
  limits:
    memory: "256Mi"

What happens if the container tries to use 300Mi of memory?

medium

A. The container is allowed to use 300Mi without issues

B. The container is throttled but not killed

C. The container is killed by Kubernetes for exceeding the memory limit

D. The container's memory usage is capped at 256Mi but continues running

Solution

1. Step 1: Understand memory limit enforcement

   Memory limit is the maximum memory a container can use. If it exceeds this, Kubernetes kills the container.

2. Step 2: Apply to given values

   The limit is 256Mi. Using 300Mi exceeds this limit, so the container will be terminated.

3. Final Answer:

   The container is killed by Kubernetes for exceeding the memory limit -> Option C

4. Quick Check:

   Memory usage > limit = container killed [OK]

Hint: Memory over limit kills container, not throttled [OK]

Common Mistakes:

• Thinking container is throttled instead of killed
• Confusing requests with limits
• Assuming container can burst beyond limit safely

4. You set memory requests to 512Mi and limits to 256Mi in your pod YAML. What is the problem?

medium

A. Memory limits cannot be lower than 256Mi

B. Memory requests cannot be higher than memory limits

C. This configuration is valid and will work fine

D. Requests and limits must be equal

Solution

1. Step 1: Recall relationship between requests and limits

   Memory requests must be less than or equal to memory limits. Requests are minimum guaranteed, limits are max allowed.

2. Step 2: Analyze given values

   Requests = 512Mi, Limits = 256Mi. Requests are higher than limits, which is invalid and causes an error.

3. Final Answer:

   Memory requests cannot be higher than memory limits -> Option B

4. Quick Check:

   Requests ≤ Limits rule violated [OK]

Hint: Requests must be ≤ limits, else config error [OK]

Common Mistakes:

• Setting requests higher than limits
• Assuming limits can be lower than requests
• Thinking requests and limits can be any values

5. You want to ensure your pod always has at least 200Mi memory but never uses more than 400Mi. How should you set memory requests and limits in the pod spec?

hard

A. requests.memory: "200Mi" and limits.memory: "400Mi"

B. requests.memory: "400Mi" and limits.memory: "200Mi"

C. requests.memory: "200Mi" only, no limits

D. limits.memory: "400Mi" only, no requests

Solution

1. Step 1: Identify minimum guaranteed memory

   Minimum memory guaranteed is set by requests.memory, so set it to 200Mi.

2. Step 2: Identify maximum allowed memory

   Maximum memory allowed is set by limits.memory, so set it to 400Mi.

3. Step 3: Verify correct order

   Requests must be ≤ limits, so 200Mi ≤ 400Mi is valid.

4. Final Answer:

   requests.memory: "200Mi" and limits.memory: "400Mi" -> Option A

5. Quick Check:

   Requests = 200Mi, Limits = 400Mi [OK]

Hint: Requests = min guaranteed, limits = max allowed [OK]

Common Mistakes:

• Swapping requests and limits values
• Setting only requests or only limits
• Setting requests higher than limits