how to setup nginx not to crash if grpc server`s hostname in upstream is not found

Question

nginx version: 1.13.10

Config looks like this:

events {
multi_accept        on;
worker_connections  16384;
use                 epoll;
}
http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
            '$status $body_bytes_sent "$http_referer" '
            '"$http_user_agent"';
    server {
            listen 80 http2;

            access_log /dev/stdout main;

            location /foo.test {
                    grpc_pass grpc://foo:8088;
            }
    }
}

If the app is not started then nginx fails and stops:

We don't need them all to be up but nginx fails otherwise. How to make nginx ignore failed upstreams?

i have try this solution Setup nginx not to crash if host in upstream is not found (not grpc )

but it work for proxy_pass http proxy ,not work for grpc_pass.

does anyone have some idea ?