So I am trying to make Google cloud's API gateway serve requests from a private IP based backend. Currently, the backend is a Kubernetes based service. However, I couldn't find it explicitly being mentioned whether its possible or not.
Has anyone else encountered such an issue given that its a pretty common use case? It seems possible only when the API gateway infrastructure has a link to the VPC network(route table) or an explicit private connection.
After looking for a while I think that the best way to do what you are asking is to use Private service connect, this allows private consumption of services across VPC networks that belong to different groups, teams, projects, or organizations and also lets you connect to service producers using endpoints with internal IP addresses in your VPC network.
Here is a guide of how to use Private Service Connect to access Google APIs.
the Google API gateways exist only for serverless product and is intended to be use only against serverless backends(s). It is possible to configure it against public IP’s that are hosted on our Google backends because they leverage the same x-google-backend configuration key-value pairs in the openapi.yaml for API Gateway, but more niche features like authorization on behalf of backend services, or limiting access to backed services hosted on non-serverless platforms like GKE are currently not supported. a possible workaround could be to set up endpoints directly with your GKE cluster you, this documentation could help you first, second, third
Best regards.
