[Mageia-dev] Migrating systemd units. Be careful and please test

Sat Apr 21 17:23:13 CEST 2012

Hello,
+
+I've been trying to review the LSB initscript headers and systemd unit
+migration.
+
+It's really great to see packagers helping out here and I'd like to
+thank everyone for their effort, but sadly there have been a couple of
+errors cropping up in the process. So to help people out I'm including
+some advice in this mail. I'll also include the same advice on the
+systemd wiki page once I get around to updating it (trying to
+consolidate the list of packages there with a Google docs spreadsheet I
+have which is more detailed and easier to work with than the wiki page -
+when done with that, this info will be on the wiki).
+
+
+Be careful when copying Fedora units
+====================================
+
+Fedora use /run for .pid files. On Fedora /var/run is just a symlink to
+/run. We don't do that yet, but we will will likely do this for mga3 as
+it solves a few problems we've had to hackily work around. In the mean
+time, we should in most cases use /var/run as the PID file path. The
+only time when using /run for the PID file is when the ExecStart command
+itself has an argument for the pidfile name passed in. If these two
+match up then all is well.
+
+Also Fedora often has different syntax in /etc/sysconfig files. During
+the migration to systemd they have likely simplified a few of them too.
+Again, do not blindly assume the files are the same format. You have to
+double check what we do in our initscript with the files and take
+appropriate action. You may have to edit the initscript too if you
+simplfy the syntax and you may also want to add default values for some
+environment variables inside the unit itself.
+
+
+Be careful of naming differences to sysvinit script
+===================================================
+
+If a native systemd unit has a different name to the sysvinit script
+(ignoring the .service suffix) make sure to include a masking symlink
+such that we know the two services are the same.
+
+e.g. in dhcp-forwarder, the sysvinit script name is dhcp-fwd, but the
+systemd service is dhcp-forwarder.service. It's essential that you
+include a symlink to dhcp-forwarder.service with the name
+dhcp-fwd.service in order for both the upgrade migration and general
+running of the system to work.
+
+
+Please test the result or do not migrate for now
+================================================
+
+Some of the problems above are quite obvious when testing. Please make
+sure to test things fully.
+
+If you are in any doubt, it's probably best to NOT migrate to a native
+unit over a sysvinit script at this stage of the cycle as it could
+introduce new problems quite easily. An exception would be if the
+initscript does not have LSB headers. In this case I'm happy for either
+a native systemd unit to be added or for the sysvinit script to simply
+have LSB headers inserted.
+
+Cheers!
+
+Col
+
+-- 
+
+Colin Guthrie
+colin(at)mageia.org
+http://colin.guthr.ie/
+
+Day Job:
+  Tribalogic Limited http://www.tribalogic.net/
+Open Source:
+  Mageia Contributor http://www.mageia.org/
+  PulseAudio Hacker http://www.pulseaudio.org/
+  Trac Hacker http://trac.edgewall.org/
+