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%config(noreplace) %{_sysconfdir}/tmpfiles.d/httpd.conf | %config(noreplace) %{_sysconfdir}/tmpfiles.d/httpd.conf | ||
</pre> | </pre> | ||
Files that the program places directly into <code>/var/run</code> or <code>/var/lock</code> or into subdirectories of those may be listed in the %files section as <code>%ghost</code> but this is not required as the files will be cleaned up on every reboot. | |||
== Why not create the directories with XXXXXX instead? == | == Why not create the directories with XXXXXX instead? == |
Revision as of 22:53, 15 December 2010
tmpfiles.d is a service provided by both systemd and upstart for managing temporary files and directories. In this guideline we mainly oncentrate on how it is used to populate /var/run
and /var/lock
. In Fedora 1 and above, /var/run
and /var/lock
are tmpfs filesystems. As such, they are created empty on every reboot. For files intended to be placed into those directories, this should normally not pose any problems. For directories, however, we often need to create the directories ahead of time. This is best done using the tmpfiles.d mechanism that both upstart and systemd share.
tmpfiles.d configuration
Configuring tmpfiles.d just involves dropping a file into %{_sysconfdir}/tmpfiles.d/
that tells the init system what directories need to be created.
For example, the httpd package needs a few directories to be created in /var/run
in order for apache to run. The packager needs to create a file named apache.conf
that is installed as %{_sysconfdir}/tmpfiles.d/apache.conf
. The file has the following lines:
d /var/run/httpd 0710 root apache 1s
The format of the line is as follows:
d
specifies that a directory is to be created if it doesn't exist/var/run/httpd
is the filesystem path to create0710
are the permissions to apply to the directory when it is createdroot
is the owner of the directoryapache
is the group that owns the directory1s
the last field is for age which specifies to delete some files in the directory. For installing directories in/var/run
and/var/lock
this can be set to a very low number (here, 1 second) as the files should always be cleaned up on boot
Information on other options is available on the tmpfiles.d man page should you need to do something more advanced.
Example spec file
In the spec file, the packager needs to install the tmpfiles.d conf file and also make sure the directory is included in the rpm.
# tmpfiles.d configuration for apache's /var/run directory Source1: httpd.conf Requires: initscripts [...] %install mkdir -p %{buildroot}%{_sysconfdir}/tmpfiles.d install -m 0644 %{source1} %{buildroot}%{_sysconfdir}/tmpfiles.d/ # The next two lines may not be needed if the upstream's install script creates them mkdir -p %{buildroot}%{_localstatedir}/run/ install -d -m 0710 %{buildroot}%{_localstatedir}/run/httpd/ [...] %files %defattr(0644, root, root, 0755) %dir %{_localstatedir}/run/httpd/ %config(noreplace) %{_sysconfdir}/tmpfiles.d/httpd.conf
Files that the program places directly into /var/run
or /var/lock
or into subdirectories of those may be listed in the %files section as %ghost
but this is not required as the files will be cleaned up on every reboot.
Why not create the directories with XXXXXX instead?
There are multiple ways to try creating the directories but most suffer some disadvantage that tmpfiles.d addresses:
Have the daemon create the directory when it starts up
Many times, daemons run as an unprivileged user who would not be allowed to create new directories directly into /var/run
or /var/lock
.
Have the init script create the directory when it starts up the daemon
Since the init script is run by root, before the daemon drops privileges, why not create the directories there?
- This code would need to be implemented in every init script packaged. Since both upstart and systemd support tmpfiles.d, we can cut down on the number of places we have to put code like this.
- Having to add the mkdir to the systemd unit files when tmpfiles.d is already in place introduces the need to run shell code for that init script. Systemd is no longer able to handle starting the daemon by itself which slows things down. The shell code also introduces imperative constructs into the otherwise declarative structure which is nice to avoid.
- Properly labelling the created directories is done automatically by the tmpfiles.d mechanism but would have to be manually done by the init script.