Re: systemd vnc - how to properly handle /etc/sysconfig/vncservers

2011-07-20 Thread Tim Waugh
On Wed, 2011-07-20 at 11:48 +0200, Adam Tkac wrote:
 Any idea how to handle the VNCSERVERS argument in backward-compatible
 way is welcomed, otherwise I will simply drop sysconfig support at all
 in the service file and admin will have to create /etc/systemd/system/
 service files with appropriate params.

IMHO dropping the sysconfig support and having separate systemd unit
files for each session is the best approach.

Tim.
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Re: systemd vnc - how to properly handle /etc/sysconfig/vncservers

2011-07-20 Thread Lennart Poettering
On Wed, 20.07.11 11:48, Adam Tkac (at...@redhat.com) wrote:

 Hello all,
 
 I'm trying to package systemd service file for tigervnc server and to
 find a solution how to make it backward-compatible with current format
 of the /etc/sysconfig/vncservers.
 
 Current /etc/sysconfig/vncservers has following options (example):
 
 VNCSERVERS=1:user1 2:user2
 VNCSERVERARGS[1]=-arg1 -arg2
 VNCSERVERARGS[2]=-arg3 -arg4
 
 With arguments above traditional SysV initscript starts Xvnc instances
 for displays :1 and :2 which run under appropriate user (user1 and user2
 in this example) and passes arguments to Xvnc.
 
 If I understand systemd correctly it's a bad idea to try start multiple
 instances of the Xvnc via one systemd service file - I'm fine with this,
 admin will have to create multiple service files for multiple Xvnc
 instances.
 
 However is there any way how to extract correct bits from the sysconfig
 file? I think it's easy with the VNCSERVERARGS[num] variable but I don't
 have any idea how to extract proper user from the VNCSERVERS variable.
 Does systemd support some kind of regex matching for the $name 
 variables got from sysconfig files?
 
 Any idea how to handle the VNCSERVERS argument in backward-compatible
 way is welcomed, otherwise I will simply drop sysconfig support at all
 in the service file and admin will have to create /etc/systemd/system/
 service files with appropriate params.

You have a couple two options here:

a) I think this is one of the cases where the configuration in sysconfig
is just too cumbersome and a proper configuration file would bre really
useful. (It might even be an option to just fold this into gdm, so that
clients dynamically get a new screen). This of course requires hacking
vnc and/or gnome, so is not a short-term thing.

b) If you want to keep full compatibility with the sysconfig file, place
a start-up script in /usr/lib/vnc/start-vncserver-instance or so, which parses
it. Then, use instantiated systemd services, to instantiate individual
ones. Example:

snip
[Unit]
Description=VNC for %i

[Service]
ExecStart=/usr/lib/vnc/start-vnc-instance %i
/snip

Place that in /lib/systemd/vncserver@.service or so. If a user then
wants to start a vnc server for a user, it is sufficien to run
systemctl start vncserver@1:lennart.service which would then cause
/usr/lib/vnc/start-vnc-instance 1:lennart to be started. Or, to make
this permanent: ln -s /lib/systemd/vncserver@.service
/etc/systemd/multi-user.target.wants/vncserver@1:lennart.service.

Presumably most users will just use the same vnc server configuration,
and hence a couple of ln -s would be everything needed to instantiate
vnc for the users. If there's point in passing specific arguments to the
service for a specific user, then the admin should just copy
/lib/systemd/vncserver@.service to
/etc/systemd/vncserver@1:lennart.service and edit it there. You can do
this for individual users.

Hope this clears some things up.

Lennart

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