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

[Thomas HUMMEL <thomas hummel pasteur fr>]

On 4/27/20 7:05 PM, Thomas HUMMEL wrote:


> hostname(1) change the transient/kernel hostname but as 
> systemd-hostnamed does not poll /proc/sys/kernel/hostname (which was 
> confirmed to my in the systemd-devel list) for a change, this out-of-NM 
> set hostname is not seen by NM, which then restores the last outside one 
> seen BY himself, which is the hostname-original read from dbus at its 
> start ?

I actually did the test changing *only* the presence or absence of 
systemd-hostnamed (brutally renaming to systemd-hostnamed.service.orig 
in /usr/lib/systemd/system for the test) :

Each time withouth changing hostname-mode (directive was not there so 
its value is default) :

a) without systemd-hostnamed : short hostname
b) with systemd-hostnamed : fqdn

[again with an external tool issuing hostname(1) between dhcp and manual 
profile]

So it seems to me that, because of hostnamed lack of polling for 
transient hostname change, NetworkManager could behave differently 
according if this service it uses as a proxy is there or not (i.e. if NM 
reads directly using gethostname(3)) : the 'last hostname set outside of 
NetworkManager could vary.

What do you think ?

Note : this could be more complicated because, as systemd.hostnamed 
deactivates itsef when idle, I wonder if a fresh instance would not 
start by setting the transient hostname to the static hostname (which is 
quite the goal of the static hostname to me). So this would give another 
result if the get-hostname() waited a little more ?

Thanks

--
Thomas HUMMEL