Connection Refused with nginx and kubernetes

I found the solution. The problem was with my requests, I was using localhost at the URL, with that I took the wrong pod IP. I've just changed the request to use straight the service IP and that sort out my problem.

Kubernetes Engine nodes are provisioned as instances in Compute Engine. As such, they adhere to the same stateful firewall mechanism as other instances. Have you configured the firewall rules?

https://cloud.google.com/solutions/prep-kubernetes-engine-for-prod#firewalling

Good that you have figured out the issue. But, Did you try using the service_names instead of the Pod IPs? It is suggested method(https://kubernetes.io/docs/tasks/administer-cluster/access-cluster-services/#manually-constructing-apiserver-proxy-urls) of accessing services by their names within the Kubernetes cluster and with NodeIP or LoadBalancerIP outside the cluster.