DevOps Classroom notes 03/Feb/2024

Managed Kubernetes (Kubernetes as a Service)

• All the CSP offer k8s as a service
  • AWS = EKS
  • Azure = AKS
  • GCP = GKE

Architecture of k8s as a service

• All the clouds manage control plane and charge hourly for that
• Nodes can be added by at normal virtual machine costs
  
• K8s as a service provides node autoscaling
• They provide options for
  • networking
    • integrate with cloud load balancers
    • integrate with cloud virtual networks
    • support for layer 7 load balancing with ingress
    • support for third party cni
  • storage
    • Volume integration with cloud based disk storages and other storage options
  • Authentication and authorization (A & A)
    • support k8s native A & A
    • extends A & A to cloud based IAM
  • Administration:
    • Backup of k8s clusters
    • Upgrading k8s clusters
  • Pod based billing

AKS: Azure kubernetes Cluster

• Refer Here for official docs of Azure kuberentes service.
• Refer Here for quick start to create aks cluster

Namespaces

• Namespace is a logical cluster for organizing k8s resources.
• By default in k8s cluster we have following namespaces
  • default
  • kube-system
  • kube-public
• Kuberentes resources can be scoped to a
  • namespace (namespaced = true)
  • cluster (namespace = false)
• use th namespaced section in kubectl api-resources to find out the scope
  • examples of namespace scope
    • pods
    • services
    • deployments
    • ….
  • examples of cluster scope
    • node
    • persistent volumes
• Namespaces are generally used to
  • differentiate environments
  • assign resource limits to the namespaces
• kubectl command can query the default namespace Refer Here

kubectl config set-context --current --namespace=dev

• note: Generally namespace is an administration convinience, adding namespaces in yaml might not be a good practice.
• Lets deploy an nginx pods and a service in dev namespace. Refer Here for manifests
  
• Lets create an nginx pod in default namespace
  
• Refer Here for namespace and dns
• Lets try providing Resource Quotas to Namespace Refer Here
• LimitRange Refer Here
• NetworkPolicy Refer Here