Configure Nginx to preserve external IP

Update the gitlab deployment with `gitlab_rails['trusted_proxies']`, and add annotation to Nginx service to support preservation of external IPs to internal nodes.

This is now available because of the availability of k8s 1.5.x on GKE, where as it was not previously.

gitlab/gitlab-deployment.yml

@@ -127,6 +127,7 @@ spec:
             gitlab_rails['uploads_directory'] = '/gitlab-data/uploads'
             gitlab_ci['builds_directory'] = '/gitlab-data/builds'
             gitlab_rails['registry_path'] = '/gitlab-registry'
+            gitlab_rails['trusted_proxies'] = ["10.0.0.0/8"]
             prometheus['enable'] = true
             node_exporter['enable'] = true

load-balancer/nginx/service.yaml

@@ -3,6 +3,8 @@ kind: Service
 metadata:
   name: nginx
   namespace: nginx-ingress
+  annotations:
+    service.beta.kubernetes.io/external-traffic: "OnlyLocal"
 spec:
   type: LoadBalancer
   loadBalancerIP: @GITLAB_GKE_IP@