Yep, you define the mapping between the domain name and the internal container port as `x-ports: app.example.com:8000/https` in the compose file. Or you can specify a custom Caddy config for the service as `x-caddy: Caddyfile` which allows to customise it however you like. See https://uncloud.run/docs/concepts/ingress/publishing-service...
>if I deploy 2 compose 'stacks', do all containers have access to all other containers, even in the other stack?
Yes, there is no network isolation between containers from different services/stacks at the moment. Here is an open discussion on stack/namespace/environment/project concepts and isolation: https://github.com/psviderski/uncloud/discussions/94.
What's your use case and how would you want this to behave?