For instance how can I use my *.domain.com SSL certs and NPM to route containers to a subdomain without exposing them? The main domain is exposed.
For instance how can I use my *.domain.com SSL certs and NPM to route containers to a subdomain without exposing them? The main domain is exposed.
OP is asking for cases where you don’t want to allow the service (or reverse proxy) to be accessible via the web.
I guess they need a CA then
https://smallstep.com/docs/step-ca/
They do not. See my other reply about DNS verification.
Your response clearly states publicly accessible DNS. A CA does not require anything public for local SSL and can work in conjunction with whatever service they want for that which is public.
Fair, I don’t know why I read OPs post as asking for let’s encrypt certs. Internal CA is indeed an option.