Hi @AJ1—by default, we shut down your application by sending it an interrupt signal (SIGINT). Python converts that signal into a KeyboardInterrupt exception, which I think is why you’re seeing it when you deploy (it’s the Machine shutting down before restarting). The same will probably happen if your Machine is automatically stopped (auto_stop_machines = true in fly.toml).
I just double-checked on our end, and it looks like your app has a shared IPv4 address. Since gRPC requires you to set up a raw TCP service (which you’ve done), you’ll need a dedicated IPv4 address to be able to access your app over IPv4. The link will show you how to allocate one; just be aware that dedicated IPv4 addresses are $2/month.
Otherwise, the stack trace does indicate that your app is starting and reaching the serve function, so I’m not sure what else might be an issue. (Is it still true that you do not see the server starting on {address} line printed in the logs?)