Kubernetes - Requests and Limits¶

Step-01: Introduction¶

• We can specify how much each container in a pod needs the resources like CPU & Memory.
• When we provide this information in our pod, the scheduler uses this information to decide which node to place the Pod on based on availability of k8s worker Node CPU and Memory Resources.
• When you specify a resource limit for a Container, the kubelet enforces those limits so that the running container is not allowed to use more of that resource than the limit you set.
• The kubelet also reserves at least the request amount of that system resource specifically for that container to use.

Azure Kubernetes Service with Azure DevOps and Terraform¶

Pre-requisite Check (Optional)¶

• We should already have our AKS Cluster UP and Running.
• We should have configured our AKS Cluster credentials in command line to execute kubectl commands

  # Configure AKS Cluster Credentials from command line
  az aks get-credentials --name aksdemo1 --resource-group aks-rg1
  
  # List Worker Nodes
  kubectl get nodes
  kubectl get nodes -o wide
  

Step-02: Add Requests & Limits & Review k8s Manifests¶

• Folder: kube-manifests-v1

            # Requests & Limits    
            resources:
              requests:
                cpu: "100m" 
                memory: "128Mi"
              limits:
                cpu: "200m"
                memory: "256Mi"                                                         
  

Step-03: Create k8s objects & Test¶

# Create All Objects
kubectl apply -f kube-manifests-v1/

# List Pods
kubectl get pods

# List Services
kubectl get svc

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

Step-04: Clean-Up¶

• Delete all k8s objects created as part of this section

  # Delete All
  kubectl delete -f kube-manifests-v1/
  

Step-05: Assignment¶

• You can deploy and test kube-manifests-v2
• Verify the Resources section in file 05-UserMgmtWebApp-Deployment.yml before deploying

  # Create All Objects
  kubectl apply -f kube-manifests-v2/
  
  # List Pods
  kubectl get pods
  
  # List Services
  kubectl get svc
  
  # Access Application 
  http://<Public-IP-from-List-Services-Output>
  Username: admin101
  Password: password101
  
  # Clean-Up
  kubectl delete -f kube-manifests-v2/
  

References:¶

• https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/

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