Kubernetes Practices

Prerequisites

Install KVM or VirtualBox

Install Ubuntu / Debian on KVM or VirtualBox

Install Minikube

Check K8s version and config

kubectl version
kubectl config
kubectl cluster-info

Get / Describe command

kubectl get ndoes
kubectl get pods
kubectl get deployments
kubectl get services

kubectl describe pods

Deploy hello-world node demo app

• Deploy a demo app

  kubectl run kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1 --port=8080
  
  # View deployments and pods
  kubectl get deployments
  kubectl get pods
  

• Pods that are running inside Kubernetes are running on a private, isolated network. By default they are visible from other pods and services within the same kubernetes cluster, but not outside that network.

• The kubectl command can create a proxy that will forward communications into the cluster-wide, private network.

  # Create a proxy from another terminal
  kubectl proxy
  
  # Test it from original termianl
  curl http://localhost:8001/version
  

• Get pod name

  export POD_NAME=$(kubectl get pods -o go-template --template \
   '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}')
  echo Name of the Pod: $POD_NAME
  kubectl logs $POD_NAME
  

• Execute command on containter

  kubectl exec $POD_NAME env
  kubectl exec $POD_NAME bash
  kubectl exec $POD_NAME curl localhost:8080
  

• Scale demo app with replica

  # kubernetes-bootcamp   deployment is the same as above
  kubectl get pods -o wide
  kubectl describe deployments/kubernetes-bootcamp    
  kubectl scale deployments/kubernetes-bootcamp --replicas=2
  
  # Get NodePort
  export NODE_PORT=$(kubectl get services/kubernetes-bootcamp \
      -o go-template='{{(index .spec.ports 0).nodePort}}')
  echo NODE_PORT=$NODE_PORT
  
  # Test load balance
  curl $(minikube ip):$NODE_PORT