Hello World Application in a Cluster using Minikube

Minikube (Kubernetes deployment locally on Linux machine)

Minikube is a tool that makes it easy to run Kubernetes locally. Minikube runs a single-node Kubernetes cluster inside a VM

Install kubectl (Installed from here locally:)

https://kubernetes.io/docs/tasks/tools/install-kubectl/

Install Minikube (Installed from here locally:)

https://github.com/kubernetes/minikube/releases

$ minikube start --vm-driver=hyperkit   (Run kubernetes components locally if you are using mac)Get the IP of the local kubernetes cluster: $minikube ip
SSH into the minikube VM: $minikube ssh
$minikube dashboard
$minikube service list

Execute locally:

$ minikube start #(default driver is vbox)
#(spin up minikub VM in vobx, kubernetes server/master start)$ minikube status #(show status like ip)
$ minikube dashboard #(Open dashboard in browser)
$ minikube stop #(stop kubernetes server/master)
$ kubectl version
$ kubectl config current-context
$ kubectl cluster-info
$ kubectl cluster-info dump
$ kubectl get nodes
$ kubectl get services
$ kubectl get deployment
$ kubectl get pods
$ kubectl get pods --all-namespaces
$ kubectl get events

Run five instances of a Hello World application. Create a Service object that exposes an external IP address. Use the Service object to access the running application.

Run a Hello World application in your cluster:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/name: load-balancer-example
  name: hello-world
spec:
  replicas: 5
  selector:
    matchLabels:
      app.kubernetes.io/name: load-balancer-example
  template:
    metadata:
      labels:
        app.kubernetes.io/name: load-balancer-example
    spec:
      containers:
        - image: gcr.io/google-samples/node-hello:1.0
          name: hello-world
          ports:
            - containerPort: 8080

save as load-balancer-example.yaml

in the terminal, run following cmds.

mkdir hello-world-app
cd hello-world-appsubl . # open folder using sublime

kubectl create -f load-balancer-example.yaml

The preceding command creates a Deployment object and an associated ReplicaSet object. The ReplicaSet has five Pods, each of which runs the Hello World application.

Display information about the Deployment:

kubectl get deployments hello-world
kubectl describe deployments hello-world

Display information about your ReplicaSet objects:

kubectl get replicasets
kubectl describe replicasets

Create a Service object that exposes the deployment:

kubectl expose deployment hello-world --type=LoadBalancer --name=my-service

Display information about the Service:

kubectl get services my-service The output is similar to this:

NAME         TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
my-service   LoadBalancer   10.96.109.232   <pending>     8080:31518/TCP   4m5s

Display detailed information about the Service:

kubectl describe services my-service The output is similar to this:

Name:                     my-service
Namespace:                default
Labels:                   app.kubernetes.io/name=load-balancer-example
Annotations:              <none>
Selector:                 app.kubernetes.io/name=load-balancer-example
Type:                     LoadBalancer
IP:                       10.96.109.232
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  31518/TCP
Endpoints:                172.17.0.10:8080,172.17.0.13:8080,172.17.0.14:8080 + 2 more...
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>
Ayeshas-MacBook-Pro:simple-hello-world-app-deployment ayeshakaleem$ kubectl describe services my-service
Name:                     my-service
Namespace:                default
Labels:                   app.kubernetes.io/name=load-balancer-example
Annotations:              <none>
Selector:                 app.kubernetes.io/name=load-balancer-example
Type:                     LoadBalancer
IP:                       10.96.109.232
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  31518/TCP
Endpoints:                172.17.0.10:8080,172.17.0.13:8080,172.17.0.14:8080 + 2 more...
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

check minikube ip by using the following command.

minikube ip you will get the IP then curl in your browser

curl http://<minikube-ip>:<port>
for example:
http://192.168.64.3:31518/

In the preceding output, you can see that the service has several endpoints: 172.17.0.10:8080,172.17.0.13:8080,172.17.0.14:8080 + 2 more. These are internal addresses of the pods that are running the Hello World application. To verify these are pod addresses, enter this command:

kubectl get pods --output=wide

The output is similar to this:

NAME                          READY   STATUS              RESTARTS   AGE     IP            NODE       NOMINATED NODE   READINESS GATES
hello-world-f9b447754-7ccjm   1/1     Running             0          3h35m   172.17.0.16   minikube   <none>           <none>
hello-world-f9b447754-89hfv   1/1     Running             0          3h35m   172.17.0.10   minikube   <none>           <none>
hello-world-f9b447754-gc9g5   1/1     Running             0          3h35m   172.17.0.14   minikube   <none>           <none>
hello-world-f9b447754-pwwmt   1/1     Running             0          3h35m   172.17.0.13   minikube   <none>           <none>
hello-world-f9b447754-z9hld   1/1     Running             0          3h35m   172.17.0.15   minikube   <none>           <none>

Use the minikube IP address to access the Hello World application:

minikube service my-service

Typing above command will automatically open the Hello World application in a browser.

The response to a successful request is a hello message:

Hello Kubernetes!

Cleaning up To delete the Service, enter this command:

kubectl delete services my-service To delete the Deployment, the ReplicaSet, and the Pods that are running the Hello World application, enter this command:

kubectl delete deployment hello-world

References:

https://www.bogotobogo.com/DevOps/DevOps-Kubernetes-1-Running-Kubernetes-Locally-via-Minikube.php

https://hackernoon.com/containerizing-a-node-js-api-using-docker-with-kubernetes-and-minikube-30255fd33ef9

https://auth0.com/blog/load-balancing-nodejs-applications-with-nginx-and-docker/