"Hostname is illegal" when attempting to connect nodes

Can you provide examples of the host names you’re trying to use?

Sure thing!

Example 1

Node.connect(:"core_repo@core-repo")

Example 2

Node.connect(:"core_repo@corerepo")

Could you please search the codebase for <hostname>? It might be some default value somewhere. I think I saw it once in the templates distillery generates.

I assume the hostnames are valid. They must be FQDN and I think they must resolve to an IP address

It seems as if you started your BEAM in “long name” mode, and in long name mode at least one dot is expected in the hostname to make the BEAM recognize it as “fully qualified”, localhost might be an exception of this rule, but I’m not quite sure about that.

Sorry, <hostname> is just a placeholder I used.

I’ve placed the real messages below.

** System running to use fully qualified hostnames **
** Hostname core-repo is illegal **

and

** System running to use fully qualified hostnames **
** Hostname corerepo is illegal **

> iex --name core_repo@core-repo
iex(core_repo@core-repo)1> ...

But then in another terminal

> iex --name core_repo@corerepo
Protocol 'inet_tcp': the name core_repo@corerepo seems to be in use by another Erlang node

So it seems like it’s not possible to run both since the dash - seems to be removed from core-repo and it then conflicts with corerepo …

I’m not running both core-repo and corerepo at the same time. I was alternating the use to see if I could get one to work.

Interesting. Putting a . at the end of the hostname doesn’t cause the error to pop up.

I’ll keep digging here.

To elaborate. core_repo@core_repo is not a valid name. It is not Fully Qualified Domain Name (Fully qualified domain name - Wikipedia).

You need something like core_repo@core_repo.yourdomain.com. And that FQDN must resolve to an IP address of the node you are using so that they can communicate.

That is why IP addresses works.