Resource quotas per namespace in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Check current resource quotas in a namespace

You run the command kubectl get resourcequota -n dev. What output do you expect if no resource quotas are set in the dev namespace?

Kubernetes

kubectl get resourcequota -n dev

A

NAME      AGE
cpu-quota  10d

B No resources found in dev namespace.

C Error from server (NotFound): resourcequotas "dev" not found

D

NAME      CPU    MEMORY
quota1    2      4Gi

💡 Hint

Think about what kubectl shows when no resource quotas exist in a namespace.

If no resource quotas exist in the specified namespace, kubectl shows a message indicating no resources found. It does not show errors or quota details.

❓ Configuration

intermediate

Define a resource quota limiting CPU and memory

Which YAML snippet correctly defines a resource quota named limit-quota in namespace test that limits CPU to 2 cores and memory to 4Gi?

A

apiVersion: v1
kind: ResourceQuota
metadata:
  name: limit-quota
  namespace: test
spec:
  hard:
    cpu: 2 cores
    memory: 4Gi

B

apiVersion: v1
kind: ResourceQuota
metadata:
  name: limit-quota
spec:
  hard:
    cpu: 2
    memory: 4Gi
  namespace: test

C

apiVersion: v1
kind: ResourceQuota
metadata:
  name: limit-quota
  namespace: test
spec:
  limits:
    cpu: "2"
    memory: 4Gi

D

apiVersion: v1
kind: ResourceQuota
metadata:
  name: limit-quota
  namespace: test
spec:
  hard:
    cpu: "2"
    memory: 4Gi

💡 Hint

Check the correct placement of namespace and the 'hard' field format.

The namespace is set under metadata. The resource limits go under spec.hard with values as strings. CPU is specified as "2" (string), not 2 (number) or '2 cores'.

❓ Troubleshoot

advanced

Why is a pod creation failing due to resource quota?

You have a resource quota limiting pods to 5 in namespace prod. You try to create a 6th pod and get this error: pods "mypod" is forbidden: exceeded quota: pod-quota, requested: pods=1, used: pods=5, limited: pods=5. What is the root cause?

A The namespace has reached the maximum allowed pods defined by the resource quota.

B The pod spec requests more CPU than allowed by the quota.

C The pod name conflicts with an existing pod in the namespace.

D The resource quota is not applied to the namespace.

💡 Hint

Look at the error message details about pods and quota limits.

The error clearly states the pod count requested exceeds the quota limit of 5 pods in the namespace, so the creation is blocked.

🔀 Workflow

advanced

Steps to update an existing resource quota

You want to increase the CPU limit in an existing resource quota named cpu-quota in namespace dev from 2 to 4 cores. Which sequence of commands is correct?

A

kubectl get resourcequota cpu-quota -n dev -o yaml > quota.yaml
Edit quota.yaml to set cpu: "4"
kubectl apply -f quota.yaml -n dev

B

kubectl edit resourcequota cpu-quota -n dev
Change cpu to 4
Save and exit

C All of the above sequences are correct

D kubectl patch resourcequota cpu-quota -n dev --type='merge' -p '{"spec":{"hard":{"cpu":"4"}}}'

💡 Hint

Consider different ways kubectl allows editing resources.

All three methods (export-edit-apply, kubectl edit, and kubectl patch) are valid ways to update resource quotas in Kubernetes.

✅ Best Practice

expert

Why use resource quotas per namespace in a multi-team cluster?

What is the main benefit of applying resource quotas per namespace in a Kubernetes cluster shared by multiple teams?

A It prevents any single team from using more than their fair share of cluster resources, ensuring fair resource distribution.

B It automatically scales pods up and down based on team usage.

C It encrypts all data stored in the namespace to secure team data.

D It allows teams to bypass cluster-wide security policies.

💡 Hint

Think about resource fairness and limits in shared environments.

Resource quotas limit resource consumption per namespace, preventing teams from exhausting cluster resources and ensuring fair sharing.

Practice

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

easy

A. To limit the amount of resources like CPU and memory used in that namespace

B. To increase the CPU speed of all pods in the namespace

C. To delete unused pods automatically

D. To backup data stored in the namespace

Solution

1. Step 1: Understand ResourceQuota purpose

   A ResourceQuota sets limits on resource usage like CPU, memory, pods, and storage within a namespace.

2. Step 2: Compare options with purpose

   Only To limit the amount of resources like CPU and memory used in that namespace correctly describes limiting resource usage. Other options describe unrelated actions.

3. Final Answer:

   To limit the amount of resources like CPU and memory used in that namespace -> Option A

4. Quick Check:

   ResourceQuota limits resources = D [OK]

Hint: ResourceQuota controls resource limits per namespace [OK]

Common Mistakes:

• Thinking ResourceQuota speeds up pods
• Confusing quotas with backups
• Assuming quotas delete pods automatically

2. Which of the following is the correct YAML snippet to define a CPU limit of 2 cores in a ResourceQuota?

easy

A. hard:
limits.cpu: "2"

B. resources:
limits:
cpu: "2"

C. hard:
cpu: "2"

D. hard:
limits.cpu: 2

Solution

1. Step 1: Recall ResourceQuota syntax for limits

   ResourceQuota uses the hard field with resource names like limits.cpu as keys and string values.

2. Step 2: Check each option's syntax

   hard: limits.cpu: "2" correctly uses hard: with limits.cpu: "2". resources: limits: cpu: "2" uses wrong keys, C misses limits., D uses number instead of string.

3. Final Answer:

   hard: limits.cpu: "2" -> Option A

4. Quick Check:

   ResourceQuota hard limits use string values with resource keys [OK]

Hint: ResourceQuota limits use 'hard' with string values [OK]

Common Mistakes:

• Using numeric values instead of strings
• Omitting 'limits.' prefix in resource keys
• Placing limits under wrong YAML keys

3. Given this ResourceQuota YAML applied to namespace dev:

apiVersion: v1
kind: ResourceQuota
metadata:
  name: dev-quota
  namespace: dev
spec:
  hard:
    pods: "3"
    requests.cpu: "1"
    requests.memory: "1Gi"

What happens if you try to create a 4th pod in dev namespace?

medium

A. The pod will be created normally without any error

B. The pod will be created but with limited CPU

C. The pod creation will fail due to exceeding the pod count quota

D. The pod will be created but memory will be limited to 1Gi

Solution

1. Step 1: Understand pod count limit in ResourceQuota

   The quota limits pods to 3 in the dev namespace.

2. Step 2: Effect of creating 4th pod

   Creating a 4th pod exceeds the pod count quota, so Kubernetes rejects the creation with an error.

3. Final Answer:

   The pod creation will fail due to exceeding the pod count quota -> Option C

4. Quick Check:

   Pod count quota exceeded = creation fails [OK]

Hint: Pod count quota blocks pods beyond limit [OK]

Common Mistakes:

• Assuming pod is created with limited resources
• Thinking quota only warns but allows creation
• Confusing CPU/memory limits with pod count

4. You applied this ResourceQuota YAML but it fails to create:

apiVersion: v1
kind: ResourceQuota
metadata:
  name: test-quota
  namespace: test
spec:
  hard:
    cpu: "2"
    memory: "4Gi"

What is the likely error?

medium

A. Missing 'apiVersion' field

B. Namespace 'test' does not exist

C. Values should be numbers, not strings

D. Resource keys 'cpu' and 'memory' are invalid; should use 'limits.cpu' and 'limits.memory'

Solution

1. Step 1: Check resource keys in ResourceQuota

   ResourceQuota requires full resource names like limits.cpu or requests.memory, not just cpu or memory.

2. Step 2: Validate YAML fields

   API version is present, namespace existence is unrelated to syntax error, and values must be strings (which they are).

3. Final Answer:

   Resource keys 'cpu' and 'memory' are invalid; should use 'limits.cpu' and 'limits.memory' -> Option D

4. Quick Check:

   Use full resource keys like limits.cpu [OK]

Hint: Use full resource keys like limits.cpu in quotas [OK]

Common Mistakes:

• Using short keys like 'cpu' instead of 'limits.cpu'
• Assuming missing namespace causes syntax error
• Using numeric values instead of strings

5. You want to limit a namespace to 5 pods and 2Gi memory requests, but allow unlimited CPU. Which ResourceQuota YAML snippet achieves this?

hard

A. spec:
hard:
pods: "5"
requests.memory: "2Gi"
requests.cpu: "0"

B. spec:
hard:
pods: "5"
requests.memory: "2Gi"

C. spec:
hard:
pods: "5"
requests.memory: "2Gi"
limits.cpu: "unlimited"

D. spec:
hard:
pods: "5"
requests.memory: "2Gi"
requests.cpu: "-1"

Solution

1. Step 1: Understand ResourceQuota limits

   To limit pods and memory requests, specify those keys under hard. Omitting CPU means no limit on CPU.

2. Step 2: Evaluate options for CPU limits

   spec: hard: pods: "5" requests.memory: "2Gi" omits CPU limits, allowing unlimited CPU. Options A, C, D try to set CPU limits with invalid or restrictive values.

3. Final Answer:

   spec: hard: pods: "5" requests.memory: "2Gi" -> Option B

4. Quick Check:

   Omit CPU limit to allow unlimited CPU [OK]

Hint: Omit resource in quota to allow unlimited usage [OK]

Common Mistakes:

• Setting CPU limit to 0 or negative disables pods
• Using 'unlimited' as a value (not valid)
• Trying to limit CPU when unlimited is desired