How to access client IP of an HTTP request from Google Container Engine?

Question

I'm running a gunicorn+flask service in a docker container with Google Container Engine. I set up the cluster following the tutorial at http://kubernetes.io/docs/hellonode/

The REMOTE_ADDR environmental variable always contains an internal address in the Kubernetes cluster. What I was looking for is HTTP_X_FORWARDED_FOR but it's missing from the request headers. Is it possible to configure the service to retain the external client ip in the requests?

Answer 1

If anyone gets stuck on this there is a better approach. You can use the following annotations depending on your kubernetes version:

service.spec.externalTrafficPolicy: Local 

on 1.7

or

service.beta.kubernetes.io/external-traffic: OnlyLocal

on 1.5-1.6

before this is not supported

source: https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/

note that there are caveats: https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/#caveats-and-limitations-when-preserving-source-ips