[Nut-upsdev] RFC: nut and systemd

[Michal Hlavinka]

On Wednesday, April 20, 2011 08:22:53 Charles Lepple wrote:
> On Apr 18, 2011, at 10:36 AM, Michal Hlavinka wrote:
> 
> > Hi,
> >
> > you've probably heard about systemd already. In Fedora 15, it's
> > used as default instead old SysV init system. While there is some
> > backward compatibility layer, everything is going to be ported from
> > /etc/init.d/<something> init scripts to systemd's service files
> > /lib/systemd/system/<something>.service
> 
> Haven't heard of it (still trying to wrap my brain around whatever  
> makes upstart and launchd better than SysV or BSD-style init scripts).  

In systemd everything starts at the same time (if not explicitely set 
to wait for something), because systemd acts like xinetd so it creates 
all sockets,... and start some service when really needed and so on. I'm 
not a systemd expert. In fact I don't miss any special functionality and 
given I restart server only once per 2-3 months (kernel security update) 
and using suspend on desktop, I don't care whether it boots 20 seconds 
or 2 minutes. In Fedora, there is a lot of people who like systemd and a 
lot of people who hate it :)

> I assume the following is the official home page?
> 
>     http://www.freedesktop.org/wiki/Software/systemd

yes

> 
> > 4)The systemd's way:
> > - 3 service files
> > - one for upsd and one for upsmon. This means SERVER configuration
> > from /etc/sysconfig/ups goes away.
> > - two services configured by user (ups.service/nut.service=upsd, nut- 
> > monitor.service=upsmon)
> > - upsdrvctl as on demand service (started before upsd, stoped after  
> > upsd)
> >
> >
> >
> > So, the question is: 3) or 4) ?
> 
> 
> Short answer: sounds like 4.
> 
> Arnaud probably has some thoughts about migrating from /etc/sysconfig/ 
> ups to something a little more generic across distributions  
> (nut.conf?), but if systemd doesn't use a shell to parse things (which  
> is understandable for performance), is there a good point during  
> package installation/configuration where shell scripts can be executed  
> to dynamically generate the systemd configuration files?

Yes, one can use %post script in rpm for this. But what do you want to 
do there? With systemd (whether it's 3) or 4)) it works the same way 
as init script. After installation there is new service pre-configured and 
off by default (Fedora packaging policy requires that daemons are not 
"on" by default after installation). There is no post-install configuration 
right now. Usualy we try to pre-configure package to work out of the box 
during rpm build process. If there is any gui/tui/cli tool for 
configuration we simply put it somewhere /usr/bin/ or /usr/share/.. or ...

> I know that RPM has a number of pre- and post-installation scripts,  
> but is there something for configuration that does not require re- 
> installation to change configuration? 

you can execute any script (%post, %pre, %postun, %preun,.......) from any 
rpm package using simple command without the need of reinstallation or 
something (I've never needed that command, but it exists).

> That way, slower shell scripts  
> only execute once when the system administrator changes the  
> configuration, and systemd would read those generated files.

Still the same question, what do you want/need that script for?