We are in process of setting up an infrastructure where we have several services hosted and we have separate Internal Load Balancer for each service.
If we have global Load balancer in front of internal load balancer. Can someone please help and tell me how the various services can communicate with each other. Would it be via global HTTP LB ? Is this the right approach. Would really appreciate your help.
I expect your "global load balancer" is set up with a global external IP and so reachable by external clients via the internet.
If you use an internal load balancer to further distribute the load to instances within your VPC inside the GCP project, there is no need to call the external IP to communicate with other services inside your GCP project.
You can directly execute calls against the IP address of the internal load balancer.
Note you can either let GCP allocate any free IP address within your VPC, or you can select the IP address within the address range of the selected VPC.
See also the following documentation about internal load balancers: https://cloud.google.com/compute/docs/load-balancing/internal/
You can't reuse the same Instance Group as backend for HTTP(S) Load Balancing and for an Internal Load Balancer.
What you can do is use HTTP(s) Load Balancing for both internal and external clients.
Otherwise, you can run a HTTP proxy service in the HTTP(s) Load Balancing backends, and forward the requests to the internal load balanced IP.
