Learn Kubernetes Basics

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Hello Minikube

This tutorial shows you how to run a simple Hello World Node.js app on Kubernetes using Minikube and Katacoda. Katacoda provides a free, in-browser Kubernetes environment.

Note: You can also follow this tutorial if you’ve installed Minikube locally.

Objectives

Before you begin

This tutorial provides a container image built from the following files:

minikube/server.js 
var http = require('http');

var handleRequest = function(request, response) {
  console.log('Received request for URL: ' + request.url);
  response.writeHead(200);
  response.end('Hello World!');
};
var www = http.createServer(handleRequest);
www.listen(8080);
minikube/Dockerfile 
FROM node:6.14.2
EXPOSE 8080
COPY server.js .
CMD node server.js

For more information on the docker build command, read the Docker documentation.

Create a Minikube cluster

  1. Click Launch Terminal

    Note: If you installed Minikube locally, run minikube start.

  2. Open the Kubernetes dashboard in a browser:

    minikube dashboard

  3. Katacoda environment only: At the top of the terminal pane, click the plus sign, and then click Select port to view on Host 1.

  4. Katacoda environment only: Type 30000, and then click Display Port.

Create a Deployment

A Kubernetes Pod is a group of one or more Containers, tied together for the purposes of administration and networking. The Pod in this tutorial has only one Container. A Kubernetes Deployment checks on the health of your Pod and restarts the Pod’s Container if it terminates. Deployments are the recommended way to manage the creation and scaling of Pods.

  1. Use the kubectl create command to create a Deployment that manages a Pod. The Pod runs a Container based on the provided Docker image.

    kubectl create deployment hello-node --image=gcr.io/hello-minikube-zero-install/hello-node

  2. View the Deployment:

    kubectl get deployments

    Output:

    NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
hello-node   1         1         1            1           1m

  3. View the Pod:

    kubectl get pods

    Output:

    NAME                          READY     STATUS    RESTARTS   AGE
hello-node-5f76cf6ccf-br9b5   1/1       Running   0          1m

  4. View cluster events:

    kubectl get events

  5. View the kubectl configuration:

    kubectl config view
    Note: For more information about kubectlcommands, see the kubectl overview.

Create a Service

By default, the Pod is only accessible by its internal IP address within the Kubernetes cluster. To make the hello-node Container accessible from outside the Kubernetes virtual network, you have to expose the Pod as a Kubernetes Service.

  1. Expose the Pod to the public internet using the kubectl expose command:

    kubectl expose deployment hello-node --type=LoadBalancer --port=8080

    The --type=LoadBalancer flag indicates that you want to expose your Service outside of the cluster.

  2. View the Service you just created:

    kubectl get services

    Output:

    NAME         TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
hello-node   LoadBalancer   10.108.144.78   <pending>     8080:30369/TCP   21s
kubernetes   ClusterIP      10.96.0.1       <none>        443/TCP          23m

    On cloud providers that support load balancers, an external IP address would be provisioned to access the Service. On Minikube, the LoadBalancer type makes the Service accessible through the minikube service command.

  3. Run the following command:

    minikube service hello-node

  4. Katacoda environment only: Click the plus sign, and then click Select port to view on Host 1.

  5. Katacoda environment only: Type 30369 (see port opposite to 8080 in services output), and then click

    This opens up a browser window that serves your app and shows the “Hello World” message.

Enable addons

Minikube has a set of built-in addons that can be enabled, disabled and opened in the local Kubernetes environment.

  1. List the currently supported addons:

    minikube addons list

    Output:

    addon-manager: enabled
coredns: disabled
dashboard: enabled
default-storageclass: enabled
efk: disabled
freshpod: disabled
heapster: disabled
ingress: disabled
kube-dns: enabled
metrics-server: disabled
nvidia-driver-installer: disabled
nvidia-gpu-device-plugin: disabled
registry: disabled
registry-creds: disabled
storage-provisioner: enabled

  2. Enable an addon, for example, heapster:

    minikube addons enable heapster

    Output:

    heapster was successfully enabled

  3. View the Pod and Service you just created:

    kubectl get pod,svc -n kube-system

    Output:

    NAME                                        READY     STATUS    RESTARTS   AGE
pod/heapster-9jttx                          1/1       Running   0          26s
pod/influxdb-grafana-b29w8                  2/2       Running   0          26s
pod/kube-addon-manager-minikube             1/1       Running   0          34m
pod/kube-dns-6dcb57bcc8-gv7mw               3/3       Running   0          34m
pod/kubernetes-dashboard-5498ccf677-cgspw   1/1       Running   0          34m
pod/storage-provisioner                     1/1       Running   0          34m

NAME                           TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)             AGE
service/heapster               ClusterIP   10.96.241.45    <none>        80/TCP              26s
service/kube-dns               ClusterIP   10.96.0.10      <none>        53/UDP,53/TCP       34m
service/kubernetes-dashboard   NodePort    10.109.29.1     <none>        80:30000/TCP        34m
service/monitoring-grafana     NodePort    10.99.24.54     <none>        80:30002/TCP        26s
service/monitoring-influxdb    ClusterIP   10.111.169.94   <none>        8083/TCP,8086/TCP   26s

  4. Disable heapster:

    minikube addons disable heapster

    Output:

    heapster was successfully disabled

Clean up

Now you can clean up the resources you created in your cluster:

kubectl delete service hello-node
kubectl delete deployment hello-node

Optionally, stop the Minikube virtual machine (VM):

minikube stop

Optionally, delete the Minikube VM:

minikube delete

What's next

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