use without FQDN

I'd like to try starting this service with docker compose, but as I am "inside" a network there will be no DNS resolution (from outside - that means no letsencrypt or something like this)
Is there a possibility to get this running without fully qualified domain names (e.g. without having to use init.sh)?
I tried to start it but it seems nginx is not answering (starting) without having the certificates available.