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Debugging LoadBalancer on Google Container Engine

Setting up a Kubernetes LoadBalancer for your pods on Google Container Engine is very easy. Just define a simple YAML or JSON file and do: kubectl create -f web-service.yaml.


apiVersion: v1
kind: Service
metadata:
  name: web
  labels:
    name: web
    app: web
spec:
  type: LoadBalancer
  loadBalancerIP: 
  ports:
    - port: 80
      targetPort: 3000
      protocol: TCP
  selector:
    name: web
    app: web

However I had the problem that the LoadBalancer was always refusing a connection, even when the pod was running and answering on its nodes ephemeral IP. After a lot of experimenting and searching in the wrong place, I found that the targetPort of the LoadBalancer needs to be the port of the app running INSIDE the container - in this case port 3000.

I was working under the assumption that since I had already mapped the apps port 3000 to host port 80 in the container spec, the LoadBalancer would have to target port 80.