Deploying a hello node in Kubernetes

In our Kubernetes quickstart tutorial, we showed how to prepare your Kubernetes cluster for use. At the end, you can check the status of your cluster, but... what's next?

In Kubernetes, you almost always start by creating a Deployment based on a container image. As part of this, one or more Pods (a group of one or more containers) are created.

In this tutorial , we show how to create a Kubernetes Deployment by deploying a 'hello node' container image as an example. In this example, one Pod is created, but in a practical use case, there are usually more Pods.

Creating a Kubernetes Hello Node Deployment

Step 1

Create a Deployment with the following command. We use the hello-node container image from the official Kubernetes organization for this.

kubectl create deployment hello-node --image=registry.k8s.io/echoserver:1.4

You will see the following confirmation:

deployment.apps/hello-node created

So far so good. We will immediately go through some useful management commands that allow you to check the status of different aspects of your Deployment.

Checking the status of your Deployment

Check the status of your new Deployment immediately with the command:

kubectl get deployments

If you host multiple Deployments, you will see them all with this command. If this is your only Deployment, the output looks like this:

NAME READY UP-TO-DATE AVAILABLE AGE 
hello-node 1/1 1 1 54s

Checking the status of your Pods

Next, check the status of your Pods:

kubectl get pods

The output looks like this. No matter how many Pods you have or which Deployments they belong to, you will see them all here. You can recognize your Deployment by the fact that the name of your Pod always starts with the name of your Deployment.

NAME READY STATUS RESTARTS AGE 
hello-node-74bfcb5b58-zkxdt 1/1 Running 0 1m2s

There are many more commands available. An overview of some of the most useful for managing your cluster can be found in this tutorial.

Step 2

By default, the Pod is only accessible from the internal virtual network of your Kubernetes cluster and not via the public internet. To make your hello-node container accessible to the public internet, you 'expose' the Pod as a Kubernetes Service of type 'LoadBalancer'.

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

You will see a clear confirmation:

service/hello-node exposed

You can see the status of your LoadBalancer Service (and all other Kubernetes Services on your cluster) with the command:

kubectl get services

For a new cluster, the output looks something like this:

NAME         TYPE           CLUSTER-IP       EXTERNAL-IP                       PORT(S)          AGE
hello-node   LoadBalancer   10.105.123.234   86-123-234-123.haip.transip.net   8080:30625/TCP   1m1s
kubernetes   ClusterIP      10.96.0.1                                          443/TCP          11d

Step 3

Finally, there is one more thing to do: testing your hello node Deployment.

Open a browser and go to the IP address you see at the end of step 2 under 'EXTERNAL-IP' with the addition of :8080 for the port on which the service listens, for example 86-123-234-123.haip.transip.net:8080

The external IP is in fact a subdomain. The actual IP address is the number sequence but with . instead of - for example 86.123.234.123. At any time you can also review the load balancer IP addresses in the control panel by navigating to the 'Load Balancers' tab of your cluster.

Unlike what you might expect you're not shown a 'hello world' message, but some client information:

CLIENT VALUES:
client_address=10.128.0.3
command=GET
real path=/
query=nil
request_version=1.1
request_uri=http://86-123-234-123.haip.transip.net:8080/

SERVER VALUES:
server_version=nginx: 1.10.0 - lua: 10001

HEADERS RECEIVED:
accept=text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
accept-encoding=gzip, deflate
accept-language=en-US,en;q=0.5
connection=keep-alive
host=86-105-246-14.haip.transip.net:8080
upgrade-insecure-requests=1
user-agent=Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:105.0) Gecko/20100101 Firefox/105.0
BODY:
-no body in request-

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

kubectl get services
kubectl get deployments