cc @zimbatm

/cc @fpletz and @flokli

Yeah that's why I wanted you to be involved. In my experience it's best not to use FQDN as the machine hostname but it's certainly a possibility.

What about cases where /etc/hostname itself is a fqdn?

Referring to the man-page hostname(5), it should only includes the hostname.
But we could add fqdn detection, so it does not add fqdn with duplicated domain suffix. (e.g.: foo.bar.com.bar.com)

How does this sound for you?

In that case it might be even better to disallow it entirely. Fail if the hostname is not valid.

In that case it might be even better to disallow it entirely. Fail if the hostname is not valid.

I just see there are some distros like Fedora, who add the fqdn to the /etc/hostname file.
Maybe we should keep it optional, so it does not annoy some users.

Hm, I also had a fqdn in /etc/hostname, which required me to set the services.avahi.hostName to the non-fqdn'-ed variant to get it to work.

Reading a bit on the internet, this is probably a bad idea. Can we raise a warning if networking.hostName contains a dot, and maybe still have the code here handle it gracefully?

If networking.hostName could disallow the fqdn notation it would also allow to finally get rid of the confusion. A long long time ago, it made sense to map 1 host to 1 fqdn, but these days are long gone.

feel free to cherry-pick my strict hostName change: fc7a9b82e30f819f4d08c33995002df1710bb28f

I agree with @zimbatm, but this would need some release notes, and maybe a better error message too.

feel free to cherry-pick my strict hostName change: fc7a9b8

Thx, I did cherry-pick this commit but I agree with @flokli.
Maybe it should be a warning first, until everyone adapted to the strict hostname annotation.

e.g.: networking.hostName = foo.bar.org; ->
warning: networking.hostName as fqdn is deprecated and should be separated by host and domain name. Please use following entries instead: networking.hostName=foo; networking.domain=bar.org;

@sylv-io can you add the warning and release notes?

@sylv-io can you add the warning and release notes?

Already started to work on it 👍
Do you know if there is any reference or documentation how to do it?

I assume you can just wrap networking.hostName with a warn if it contains a dot, like done in lib/types.nix for string.

Unfortunately I didn't notice this PR before I've opened #76542. I've read through the comments and added some (optional) TODOs to my PR.

@sylv-io I hope you don't mind if I close your PR in favour of #76542.

@primeos don't worry. my bad that i didn't continued to work on it 👍