Re: hostname-mode=default and hostname set outside NM

[Thomas HUMMEL <thomas hummel pasteur fr>]

On 4/22/20 8:18 PM, Thomas HUMMEL wrote:
> Hello,
>
> using NetworkManager-1.20.0-5.el8_1.x86_64 on CentOS 8.1 I tried to 
> figure out the hostname-mode semantics beyond what the manual says (I've 
> got another thread for this but somehow unrelated to the following 
> question).

> What's not clear to me is : what if the transient hostname is changed 
> outside NetworkManager after hostname-original gets read at NM start ?
> Let's say someone issues hostname foobar (instead of hostnamctl 
> --transient set-hostname foobar) while the DHCP connection is still up : 
> would that become the new set-out-of-NM hostname wich would be restored 
> when the connection is deactivated ?
>
> Technically NM could notice it directly issuing gethostname(3) but my 
> understanding is that it would rather rely on systemd-hostnamed/dbus for 
> that. The latter seems to have in some cases some delay to catch up with 
> transient hostanme.

On a related subjet :

I notices that

hostnamectl --static set-hostname <newhostname>

behavior was not the same according to the value of hostname-mode setting :

- if set to 'none' : there's a delay for the transient hostname to be 
automatically set to the manually set static one

- if set to 'dhcp' : the transient hostname is instantly aligned with 
the new static one.

Is this expected ?

Thanks

--
TH