nixos: Require networking.hostName to be a valid DNS label

This also means that the hostname must not contain the domain name part
anymore (i.e. must not be a FQDN).
See RFC 1035 [0], "man 5 hostname", or the kernel documentation [1].
Note: For legacy reasons we also allow underscores inside of the label
but this is not recommended and intentionally left undocumented.

[0]: https://tools.ietf.org/html/rfc1035
[1]: https://www.kernel.org/doc/html/latest/admin-guide/sysctl/kernel.html#domainname-hostname

Co-authored-by: zimbatm <zimbatm@zimbatm.com>
This commit is contained in:
Michael Weiss 2020-05-25 14:01:26 +02:00
parent 837ec31493
commit 993baa587c
No known key found for this signature in database
GPG key ID: 5BE487C4D4771D83
2 changed files with 23 additions and 3 deletions

View file

@ -431,6 +431,16 @@ systemd.services.nginx.serviceConfig.ReadWritePaths = [ "/var/www" ];
<literal>networking.hosts = lib.mkForce { "127.0.1.1" = [ config.networking.hostName ]; };</literal>.
</para>
</listitem>
<listitem>
<para>
The hostname (<literal>networking.hostName</literal>) must now be a valid
DNS label (see RFC 1035) and as such must not contain the domain part.
This means that the hostname must start with a letter, end with a letter
or digit, and have as interior characters only letters, digits, and
hyphen. The maximum length is 63 characters. Additionally it is
recommended to only use lower-case characters.
</para>
</listitem>
</itemizedlist>
</section>

View file

@ -376,10 +376,20 @@ in
networking.hostName = mkOption {
default = "nixos";
type = types.str;
# Only allow hostnames without the domain name part (i.e. no FQDNs, see
# e.g. "man 5 hostname") and require valid DNS labels (recommended
# syntax). Note: We also allow underscores for compatibility/legacy
# reasons (as undocumented feature):
type = types.strMatching
"^[[:alpha:]]([[:alnum:]_-]{0,61}[[:alnum:]])?$";
description = ''
The name of the machine. Leave it empty if you want to obtain
it from a DHCP server (if using DHCP).
The name of the machine. Leave it empty if you want to obtain it from a
DHCP server (if using DHCP). The hostname must be a valid DNS label (see
RFC 1035 section 2.3.1: "Preferred name syntax") and as such must not
contain the domain part. This means that the hostname must start with a
letter, end with a letter or digit, and have as interior characters only
letters, digits, and hyphen. The maximum length is 63 characters.
Additionally it is recommended to only use lower-case characters.
'';
};