IssueTracker

To solve this problem, create the two routes with different priorities, like this:

Route1: Destination:0.0.0.0/0<-------> Next hop: ILB(IN us-east1) <------> Priority:950

Route2: Destination:0.0.0.0/0<-------> Next Hop: ILB(IN us-west1) <------> Priority:951

As long as the forwarding rules aren't configured to be globally accessible, the next hops are regional. That is:

From the perspective of us-west1, this route is available:

Route2: Destination:0.0.0.0/0<-------> Next Hop: ILB(IN us-west1) <------> Priority:951

From the perspective of us-east1, this one is available:

Route1: Destination:0.0.0.0/0<-------> Next hop: ILB(IN us-east1) <------> Priority:950

It doesn't matter that these have different priorities in the route table because only one is "active" in each region (as long as global access isn't configured).