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Is there any way to make GKE clusters (in the same network) talk to each other using internal IP addresses?

I know GKE internal load balancers can handle traffic only from the same network and the same region. And I find this implementation very strange.

I understand pod IPs are routable but they are not static and can change anytime. Also, I know there is loadBalancerSourceRanges configuration option in external load balancers using which I can allow only the subnets I want but what if I want to keep every communication using internal and not using a public IP?

Is there any way to achieve what I am trying? Like configuring the Firewall Rules or anything else? or "Global routing mode" while creating the VPC network or anything?

Amit Yadav
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If you have 2 clusters in 2 different regions and you want them to communicate using internal IPs, your best option is to use nodePort service in the clusters to expose your pods and then configure a VM instance to act as a proxy for each cluster.

This will have the same effect as using the LoadBalancer service as an internal Load Balancer but it has the benefit that it will work across multiple regions. It also allows the same Load Balancer to handle requests for all your services.

The one thing you need to be careful of is overloading the proxy instance. Depending on the number of requests, you may need to configure multiple proxy instances for the cluster, each one only handline a handful of services.

Patrick W
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  • GCP will soon support stable version of [Global Access](https://cloud.google.com/kubernetes-engine/docs/how-to/internal-load-balancing#global_access_beta) feature which will make Internal Load balancers cross regional. – Amit Yadav Jan 27 '20 at 11:31
  • That will be amazing on so many levels, hopefully it will also apply to master endpoints – Patrick W Jan 27 '20 at 12:04
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Thanks to Global Access, adding networking.gke.io/internal-load-balancer-allow-global-access: "true" to annotation will allow you to communicate across regions.

"Global access is available in Beta on GKE clusters 1.16+ and GA on 1.17.9-gke.600+."

https://cloud.google.com/kubernetes-engine/docs/how-to/internal-load-balancing#global_access

hadican
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