Google Cloud HTTPS Loadbalance, how to force http to https

Just create a second forwarding rule on the load balancer for port 80. Both will use the same backend service.

If you want to forward users from http to https then you can't do this from the load balancer. You will have to set this up in your backend service. You can find more details here: https://stackoverflow.com/questions/38201969/redirecting-http-to-https-in-google-cloud/38202272

Create a static global IP address first

An Ephemeral IP or a static IP belong to any region doesn't work for the GCP HTTP(S) load balancer because it handles an IP to only a port. You can set a static global IP to both ports 80/443 on your load balancer.

I'm guessing a possible reason is that GCP load balancer doesn't belong to any region.