Deploy-a-sample-app---Kubernetes

• Write Kubernetes yaml file to deploy a sample app (You can use any publicly available app as deployment image) & make sure: a. App is highly available. b. App/Pods can be updated in rollout manner.

• Signup to killercode

• Login to Killercode

• install docker if not installed already

• open vi write a kubernetes file.

  yaml
  # deployment.yaml
  
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: sample-app
  spec:
    replicas: 3  # Adjust the number of replicas based on your high availability requirements
    selector:
      matchLabels:
        app: sample-app
    template:
      metadata:
        labels:
          app: sample-app
       spec:
         containers:
          - name: sample-app
          image: nginx:latest  # Replace with your desired publicly available app image
          ports:
          - containerPort: 80
     strategy:
       rollingUpdate:
         maxSurge: 1
         maxUnavailable: 1
         type: RollingUpdate
  
  

 apt-get update
 kubectl get nodes
 kubectl version

• This YAML file defines a Kubernetes Deployment with three replicas, ensuring high availability. The rollingUpdate strategy ensures that during a deployment update, only one new pod is created at a time (maxSurge: 1), and at least one old pod is available (maxUnavailable: 1), making the update process gradual and minimizing downtime.

• Make sure to replace nginx:latest with the actual image of the publicly available app you want to deploy.

• Apply the YAML file using the kubectl apply command:

  # bash
    kubectl apply -f deployment.yaml
  

• This will create the deployment and the necessary pods for your sample app, ensuring high availability and supporting rolling updates.

• deployments detail

   kubectl get deployments
  

  

• get nodes

  kubectl get nodes
  

• describe deployment sample-app

   kubectl describe deployment sample-app
  

  

• describe pods

  kubectl describe pods
  

  

• describe pod and app

  kubectl get pods -l app=sample-app
  

• describe pod apps 1,2,3

  kubectl describe pod sample-app-587d9c6687-2gk8r
  

  

  kubectl describe pod sample-app-587d9c6687-7cgft
  

  

  kubectl describe pod sample-app-587d9c6687-cxz4h
  

  

• get pod app details

• delete deployment

Deploy-a-sample-app via MiniKube on GCP

• All the above process is same part from installation
• install docker & minikube
• install the latest minikube stable release on x86-64 Linux using Debian package: minikube

 curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_latest_amd64.deb
 sudo dpkg -i minikube_latest_amd64.deb

• From a terminal with administrator access (but not logged in as root), run:

minikube start

• Interact with your cluster

  kubectl get po -A
  

  

  minikube kubectl -- get po -A
  

  

  alias kubectl="minikube kubectl --"
  

  

  minikube dashboard
  

  

• Deploy applications

• Create a sample deployment and expose it on port 8080:

  kubectl create deployment hello-minikube --image=kicbase/echo-server:1.0
  kubectl expose deployment hello-minikube --type=NodePort --port=8080
  

               *OR(We have deployed two applications named as hello-minikubes & sample-app)*
  

• open vi write a kubernetes file.

yaml
# deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: sample-app
spec:
  replicas: 3  # Adjust the number of replicas based on your high availability requirements
  selector:
    matchLabels:
      app: sample-app
  template:
    metadata:
      labels:
        app: sample-app
     spec:
       containers:
        - name: sample-app
        image: nginx:latest  # Replace with your desired publicly available app image
        ports:
        - containerPort: 80
   strategy:
     rollingUpdate:
       maxSurge: 1
       maxUnavailable: 1
       type: RollingUpdate

• Let’s break each line down…

- apiVersion: Specifies the Kubernetes API version. In this case, it’s using the “apps/v1” API version, which is appropriate for Deployments.
- kind: Specifies the type of Kubernetes resource. Here, it’s “Deployment,” indicating that this configuration file is defining a Deployment.
- spec: This section defines the desired state of the Deployment.
- replicas: 3: Specifies that you want to run three replicas of your application.
- selector: Describes the selector to match pods managed by this Deployment.
- matchLabels: Specifies the labels that the Replica Set created by the Deployment should use to select the pods it manages. In this case, pods with the label app: sample-app are selected.
- template: Defines the pod template used for creating new pods.
- metadata: Contains the labels to apply to the pods created from this template. In this case, the pods will have the label
- app: sample-app.
- spec: Describes the specification of the pods.
- containers: This section specifies the containers to run in the pod.
- name: sample-app: Assigns a name to the container.
- image: example-image: Specifies the Docker image to use for this container.
- ports: Defines the ports to open in the container.
- containerPort: 8080: Indicates that the container will listen on port 80.

• Apply the YAML file using the kubectl apply command:

  kubectl apply -f deployment.yaml
  

  

• It may take a moment, but your deployment will soon show up when you run:

  kubectl get services
  

  

• The easiest way to access this service is to let minikube launch a web browser for you:

  minikube service --all
  

  

• Validation

• manage your cluster

• Pause Kubernetes without impacting deployed applications:

  minikube pause
  

• Unpause a paused instance:

  minikube unpause
  

• Halt the cluster:/ stop

  minikube stop
  

  • Browse the catalog of easily installed Kubernetes services:

  minikube addons list
  

• Create a second cluster running an older Kubernetes release:

  minikube start -p aged --kubernetes-version=v1.16.1
  

• Delete Deployments - Delete all of the minikube clusters:

                                          ****