Change Kubernetes service type from LoadBalancer to NodePort and viceversa

Changing the Service type from NodePort to LoadBalancer and viceversa is useful depending on the cluster you are working on. If you are doing experiments in a local development cluster, like Kind, you don’t have a real load balancer in front of your cluster and you need to expose your services externally using a NodePort service. On contrary, if you are working on a kubernetes cluster with a proper load balancer, you can expose your services through a LoadBalancer service type that uses the load balancer domain name and port.

Convert to a LoadBalancer service

It is very likely to have a load balancer in front of your kubernetes services when you are working in a production cluster or on a kubernetes cluster hosted by a cloud provider. The load balancer is useful to expose your services using a single domain name, the load balancer domain name.

The command to convert a service type to a LoadBalancer service type is:

kubectl patch svc <service-name> -n <namespace> -p '{"spec": {"type": "LoadBalancer"}}'

Convert to a NodePort service

If you are working on a development kubernetes cluster you probably don’t have a load balancer to forward the incoming requests to the services. To connect to your services you have to expose them using a Node Port service type that open the same port on each node of the cluster. So to connect to the service in a multi-node cluster, you type the name of a node and the exposed port. Compared to a load balancer, you should know the node names before connecting to the service.

The command to convert a service type to a NodePort service type is:

kubectl patch svc <service-name> -n <namespace> -p '{"spec": {"type": "NodePort"}}'

kubectl port-forward to expose a service locally

kubectl tool contains the port-forward command to expose a service locally on the port we choose. It means you can connect to the service using localhost:port.

The command to expose the service locally is:

kubectl port-forward svc/<service-name> <local-port>:<service-port>

For instance, if you have the service frontend on port 80, to expose it locally on port 8080:

kubectl port-forward svc/frontend 8080:80

The kubectl port-forward is a process running on the foreground. So you need to open a new terminal if you want to issue new commands.

The Argo CD Getting Started guide shows different methods to access the Argo CD Api Server: using a LoadBalancer service type or a exposing the service locally using kubectl port-forward.

I personally used the combination of a NodePort service and kubectl port-forward command when working with Istio Gateways. Istio creates a LoadbBalancer service when you create a Gateway. Since I was working in a Kind cluster, I first changed the service type and then I exposed it locally.

Conclusion

Depending if you a have load balancer or not, you may need to change service type to connect to them.

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