Hi everybody,
if you maintain a package that ships a SysV initscript, this message is for you.
I've meant to write this mail in a long time. The overhaul of system-config-services for Fedora 9 revealed that some of the current SysV initscripts could be improved. System-config-services relies on the scripts to be standard-conformant[1], which means that they must have a certain structure (chkconfig, LSB headers)[2] and support certain actions (start, stop, restart, status)[3] which give appropriate exit codes[4]. Then there are scripts that technically conform to the standard, but could make system-config-services behave better with some changes.
I'll give some real life examples below, which are not to single out anybody, only as reference.
The issues I have found so far are:
- Some scripts always give a zero exit code on "status" (atd). System-config-services interprets a zero exit code as "service is running" and doesn't let the user start a service that e.g. is actually stopped. The error here may be that the return code of the status function isn't properly passed to exit.
- Some scripts give erroneous exit codes on status, e.g. openvpn gives "1" if it isn't running which is interpreted as "dead".
- Some scripts return exit codes reserved for non-status actions on "status", e.g. rpcgssd returns 6 on "status" here, probably because it isn't configured on my system. This will let such services be shown with an "unknown" status, or worse, a bogus one.
- Some scripts list a pidfile in the chkconfig/non-LSB header(*), but the daemon doesn't write it (anacron). In this case, system-config-services will wait on that file to appear, which never will happen so the service will always be listed as "stopped".
(*): The existence of a pidfile helps system-config-services tremendously because it can then just monitor the actual processes and instantly respond to status changes. The absence of a pidfile means that system-config-services can only react to intentional status changes, but won't detect a service dieing for whatever reason. If your service writes a pidfile, but your script doesn't reflect it, please add the chkconfig header "pidfile: /path/to/pidfile" and/or the LSB header "X-Fedora-Pidfile: /path/to/pidfile" (the latter one will be supported in future versions of the tool). If your service doesn't write a pidfile, well, it should ;-).
- Some scripts aren't starting long-running daemons, but execute nonrecurring actions. These often also just return a zero exit code on "status", but this doesn't reflect if they in fact have been run or not (udev-post). System-config-services can't tell one kind from the other, so while this situation isn't covered by the standard, it would be very helpful if these scripts tried to emulate a "normal" service as close as possible. I.e. if they just touched /var/lock/subsys/<name> on "start", removed it on "stop", ran "stop" then "start" on "restart" and let status return 0 or 3 depending on if that files exists. This would let the user see some reaction in the interface on their actions.
- Some scripts use backslashes for continuation in the LSB description (xinetd). In the service description of the LSB header, you can specify that lines are to be continued by having the next line start with "#<tab>" or "# " (hash + two or more spaces). Using backslashes here will let them appear in the service description which doesn't look too well.
I've already filed some bugs on that and will do so when I come across problematic initscripts, but I'd really appreciate if you could quickly check your scripts against these things because I won't find everything by myself ;-).
Thanks and feedback welcome, Nils
[1]: https://fedoraproject.org/wiki/Packaging/SysVInitScript [2]: https://fedoraproject.org/wiki/Packaging/SysVInitScript#Chkconfig_Header https://fedoraproject.org/wiki/Packaging/SysVInitScript#LSB_Header [3]: https://fedoraproject.org/wiki/Packaging/SysVInitScript#Required_Actions [4]: https://fedoraproject.org/wiki/Packaging/SysVInitScript#Exit_Codes_for_the_S... https://fedoraproject.org/wiki/Packaging/SysVInitScript#Exit_Codes_for_non-S...