Resource quotas per namespace in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Resource Quota in Kubernetes?

A Resource Quota is a limit set on the amount of compute resources (like CPU, memory) or objects (like pods, services) that can be used in a Kubernetes namespace. It helps control resource usage and prevent one team or app from using too much.

beginner

Why use Resource Quotas per namespace?

Resource Quotas ensure fair resource sharing among teams or projects by limiting how much CPU, memory, or other resources each namespace can consume. This avoids resource exhaustion and keeps the cluster stable.

beginner

Which Kubernetes object defines Resource Quotas?

The ResourceQuota object defines limits on resources in a namespace. It is created with a YAML file specifying limits like cpu, memory, pods, and services.

intermediate

What happens if a namespace exceeds its Resource Quota?

Kubernetes will reject new resource creation requests (like new pods) that exceed the quota. Existing resources keep running, but no new ones can be added until usage is below the quota.

beginner

How to check current Resource Quota usage in a namespace?

Use the command kubectl get resourcequota -n <namespace> to see quota limits and current usage in that namespace.

What does a Resource Quota limit in Kubernetes?

A The number of nodes in the cluster

B The amount of resources a namespace can use

C The version of Kubernetes running

D The number of users accessing the cluster

Resource Quotas limit resource usage like CPU, memory, and object counts within a namespace.

Which command shows Resource Quotas in a namespace?

A kubectl get pods

B kubectl describe nodes

C kubectl get resourcequota -n namespace

D kubectl get namespaces

The command 'kubectl get resourcequota -n namespace' lists quotas and usage in that namespace.

What happens if you try to create a pod exceeding the Resource Quota?

A The cluster automatically adds more resources

B The pod is created but marked as pending

C The pod is created and quota is ignored

D The pod creation is rejected

Kubernetes rejects creation of resources that exceed the quota limits.

Resource Quotas are applied at which Kubernetes scope?

A Namespace

B Cluster-wide

C Node level

D Pod level

Resource Quotas limit resource usage within a specific namespace.

Which resource can NOT be limited by a Resource Quota?

A Number of nodes

B Number of pods

C Memory usage

D CPU usage

Resource Quotas do not limit cluster nodes; they limit resources inside namespaces.

Explain what a Resource Quota is and why it is important in Kubernetes namespaces.

Think about how to share resources fairly among teams.

Describe how to create and check a Resource Quota in a Kubernetes namespace.

Focus on commands and YAML structure.

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