Hello Kubernetes

In this lab you’ll use your local machine to deploy a “Hello World!” application using Kubernetes. By the end of the lab you should be able to confirm that your GKE cluster is working.

Create the Apache Container

To Kubernetes, everything is a resource. Resources can be loaded from a file (like you’re about to do) or created automatically by a program. When resources are loaded from a file the files are YAML format. YAML files can have multiple resource definitions separated by --- on a line by themselves.

To start let’s create a pod with a default Apache server:

apiVersion: v1
kind: Pod
metadata:
  name: hello-pod
  labels:
    function: webserver
spec:
  containers:
  - name: httpd
    image: docker.io/httpd:latest
    ports:
    - containerPort: 80

Copy and paste that YAML into a file called hello-pod.yaml and apply the configuration:

$ kubectl apply -f hello-pod.yaml

Verify that the pod has started:

$ kubectl get all 

Once started inspect the pod:

$ kubectl describe pod/hello-pod

To check the Apache logs:

$ kubectl logs pod/hello-pod

Manually Access the Container

There’s no way to access the pod from outside our node yet. The kubectl command gives us a way to access a pod for debugging purposes.

$ kubectl port-forward hello-pod 8000:80 

Now browse to localhost:8000. You should see Apache’s “It works!”

Expose the Container Permanently

In order to maintain external access to the container you need to define a service. Here’s a service definition:

apiVersion: v1
kind: Service
metadata:
  name: hello-svc
spec:
  type: LoadBalancer
  selector:
    function: webserver
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80

Copy and paste that YAML into a file called hello-svc.yaml and apply the configuration:

$ kubectl apply -f hello-svc.yaml

Verify that the service is present:

$ kubectl get all 

Inspect the service more closely:

$ kubectl describe service/hello-svc

The service type LoadBalancer will cause Google to allocate an IP address for your service. The process may take a few minutes. Once you see an IP address navigate there with your browser.

Delete the Resources

Let’s clean up:

$ kubectl delete pod/hello-pod svc/hello-svc