Kubernetes Namespaces - LimitRange - Declarative using YAML¶

Step-01: Create Namespace manifest¶

• Important Note: File name starts with 00- so that when creating k8s objects namespace will get created first so it don't throw an error.

  apiVersion: v1
  kind: Namespace
  metadata:
    name: dev3
  

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Step-02: Create LimitRange manifest¶

• Instead of specifying resources like cpu and memory in every container spec of a pod defintion, we can provide the default CPU & Memory for all containers in a namespace using LimitRange

  apiVersion: v1
  kind: ResourceQuota
  metadata:
    name: ns-resource-quota
    namespace: dev3
  spec:
    limits:
      - default:
          memory: "512Mi" # If not specified the Container's memory limit is set to 512Mi, which is the default memory limit for the namespace.
          cpu: "500m"  # If not specified default limit is 1 vCPU per container 
        defaultRequest:
          memory: "256Mi" # If not specified default it will take from whatever specified in limits.default.memory
          cpu: "300m" # If not specified default it will take from whatever specified in limits.default.cpu
        type: Container                        
  

Step-03: Update all k8s manifest with namespace¶

• Update all files from with namespace: dev3 in top metadata section in folder kube-manifests/
• Example

  # Deployment Manifest metadata section
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: app1-nginx-deployment
    labels:
      app: app1-nginx
    namespace: dev3    # Added namespace
  spec:
  
  # Service Manifest metadata section
  apiVersion: v1
  kind: Service
  metadata:
    name: app1-nginx-clusterip-service
    labels:
      app: app1-nginx
    namespace: dev3   # Added namespace
  spec: 
  

Step-04: Create k8s objects & Test¶

# Create All Objects
kubectl apply -f kube-manifests/

# List Pods
kubectl get pods -n dev3 

# View Pod Specification (CPU & Memory)
kubectl get pod <pod-name> -o yaml -n dev3

# Get & Describe Limits
kubectl get limits -n dev3
kubectl describe limits default-cpu-mem-limit-range -n dev3

# List Services
kubectl get svc -n dev3

# Access Application
http://<Public-IP-from-List-Services-Output>/app1/index.html

Step-05: Clean-Up¶

• Delete all k8s objects created as part of this section

  # Delete All
  kubectl delete -f kube-manifests/
  

References:¶

• https://kubernetes.io/docs/tasks/administer-cluster/namespaces-walkthrough/
• https://kubernetes.io/docs/tasks/administer-cluster/manage-resources/cpu-default-namespace/
• https://kubernetes.io/docs/tasks/administer-cluster/manage-resources/memory-default-namespace/

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