Helm hands-on: Overriding values

As soon as you got Helm up and running and understand the basics, you can start using it.

Let’s do a small hands-on example.

Pre-requisites

• A Kubernetes cluster
• Docker installed
• Helm installed

Hello, World!

We’ll use the cloudecho helm package.

This is a small API running on Port 8080, which prints a Hello, World! on every request.

To use it, we make use of the helm repo add command.

helm repo add cloudecho https://cloudecho.github.io/charts/
helm repo update

We can install it to our cluster with the following command:

helm install my-hello cloudecho/hello -n default --version=0.1.2

And that’s it!

Check the pod

If you run now the command kubectl get pods you should see the pod up and running:

NAME                        READY   STATUS    RESTARTS   AGE
my-hello-7bfd984465-8lwwb   1/1     Running   0          10s

You can see the port of the service resource by calling kubectl get service:

NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
my-hello     ClusterIP   10.108.136.240   <none>        8080/TCP   69s

As it is running inside the cluster we cannot access it, but we can use a port forward to the Port 8080:

kubectl port-forward my-hello-7bfd984465-8lwwb 80:8080

When you access now http://localhost you should see the response of the application which is something like:

Hello, World!
2022-03-04 18:30:20.5547678 +0000 UTC

If you want to remove the release just call the following command:

helm uninstall my-hello

Overriding the default configuration

Sometimes we want to override some values of the default configuration.

For this we don’t need to clone all files. Instead create a new directory with a values yaml:

mkdir cloudecho
cd cloudecho
touch cloudecho-values.yaml

We will write our customized parameters into the cloudecho-values.yaml. Check the documentation of the Helm Chart you’re using to know which parameters you can override!

For the cloudecho chart the port can be configured through service.port.

So let’s make it run on port 8090:

service.port: 8090

And even more: When running locally, we can change the service.type to NodePort to bind the port to the node IP, so that the application is accessible without any port forwarding.

So the final cloudecho-values.yaml will look like following:

service:
  port: 8090
  type: NodePort

Let’s deploy it in our cluster.

The --values option takes the file name with our values and overrides the default ones.

helm install my-hello cloudecho/hello -n default --version=0.1.2 --values .\cloudecho-values.yaml

Now to get the port to which our application was mapped you need to call kubectl get services.

This should print you the service:

NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
my-hello     NodePort    10.108.61.98   <none>        8090:31117/TCP   3m38s

In the PORT(S) column you can see that the service is running inside it’s pod on the port 8090 and in this case on port 31117.

So if you access http://localhost:31117 you should be able to see the application now!

Further reading

• Introduction to Helm