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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