"Could not get a response" from Postman, fetching Express server

General Discussions
5

OK, got this sorted out now.

It boils down to the kind of Service being used: ClusterIP.

ClusterIP: Exposes the service on a cluster-internal IP. Choosing this value makes the service only reachable from within the cluster. This is the default ServiceType.

If I am wanting to connect to a Pod or Deployment directly from outside of the cluster (something like Postman, pgAdmin, etc.) and I want to do it using a Service, I should be using NodePort:

NodePort: Exposes the service on each Node’s IP at a static port (the NodePort). A ClusterIP service, to which the NodePort service will route, is automatically created. You’ll be able to contact the NodePort service, from outside the cluster, by requesting <NodeIP>:<NodePort>.

So in my case, if I want to continue using a Service, I’d change my Service manifest to:

apiVersion: v1
kind: Service
metadata:
  name: server-cluster-ip-service
spec:
  type: NodePort
  selector:
    component: server
  ports:
    - port: 5000
      targetPort: 5000
      nodePort: 31515

Making sure to manually set nodePort: <port> otherwise it is kind of random and a pain to use.

Then I’d get the minikube IP with minikube ip and connect to the Pod with 192.168.99.100:31515.

At that point, everything worked as expected.

But that means having separate sets of development (NodePort) and production (ClusterIP) manifests, which is probably totally fine. But I want my manifests to stay as close to the production version (i.e. ClusterIP).

There are a couple ways to get around this:

  1. Using something like Kustomize where you can set a base.yaml and then have overlays for each environment where it just changes the relevant info avoiding manifests that are mostly duplicative.

  2. Using kubectl port-forward. I think this is the route I am going to go. That way I can keep my one set of production manifests, but when I want to QA Postgres with pgAdmin I can do:

    kubectl port-forward services/postgres-cluster-ip-service 5432:5432

    Or for the back-end and Postman:

    kubectl port-forward services/server-cluster-ip-service 5000:5000

I’m playing with doing this through the ingress-service.yaml using nginx-ingress, but don’t have that working quite yet. Will update when I do. But for me, port-forward seems the way to go since I can just have one set of production manifests that I don’t have to alter.

1 Like