Hi all, We're now at the point where we want to flip the default init system for Jessie on Linux. A lot of systems have already switched over to systemd as their init system [0] and the package received a fair amount of testing and integration work over the last couple of months. This makes us pretty confident that not too much will break when we flip the default. To ensure we have enough time to fix any of the rarer problems people are likely to encounter, we should proceed with the switch as soon as possible.
The sysvinit package in wheezy is marked as an essential package. Simply removing the Essential flag from the sysvinit package and adding it to the systemd-sysv package is not sufficient if we want to make the switch within one release cycle. Thankfully, Steve Langasek already did the groundwork to make the switch within one release cycle possible. The contents of the sysvinit package were moved into a new sysvinit-core package and the sysvinit package was changed to simply become a meta package depending on an ORed list of alternative init systems [1]. Switching the default would be as simple as changing the order of the dependencies and adjusting the priorities of affected packages. Unfortunately this approach has some downsides. Most importantly it treats new installations the same as upgrades as it switches all systems to systemd forcefully removing the /sbin/init binary provided by sysvinit along with it. In case of an upgrade we want to provide additional safety measures though. So we are proposing the following scheme: a/ Upload a new "init" package. This is a new, essential package that will replace sysvinit as the package that ensures your system has an init system. We want to build this binary package from a package which is not tied to an actual init system, so we chose the init-system-helpers source package. Patch for init-system-helpers is available at [2]. b/ Demote sysvinit to Priority: optional and install an extra copy of the sysvinit binary into /lib/sysvinit/ so you can recover if your system fails to boot with systemd. This can be achieved by booting with init=/lib/sysvinit/init on the kernel command line. Patch for sysvinit is available at [3]. c/ Upload a new version of the init package which does the actual switch and changes the order via Pre-Depends: systemd-sysv | sysvinit-core. Diff[4] d/ Adjust the priorities of systemd and systemd-sysv. Assuming there are no major objections to this approach, we are going to start with this process next week. New installations ================= The new "init" package will ensure that systemd-sysv is installed as default init on Linux and by demoting the priority of sysvinit and sysvinit-core to optional those packages will not be installed anymore. Dist upgrades ============= On upgrades, the old, essential sysvinit package will be replaced by the new, non-essential sysvinit package which pulls in the new "init" package which in turn makes sure systemd-sysv is installed. The sysvinit package in Jessie will be kept as a transitional and recovery package which facilitates a smooth upgrade. It provides a safety net which will let you boot with sysvinit via the aforementioned kernel command line argument in case your system fails to boot with systemd. We also have a patch for grub [5] which will make this even more straightforward. The SysV compat tools provided by systemd-sysv (/sbin/reboot,runlevel,telinit,etc) are able to talk to sysvinit as PID 1, making this a seamless experience. Opting out of the switch ======================== If users want to opt out of the switch, they can install the sysvinit-core package which will satisfy the dependency of the "init" package. [0]: https://qa.debian.org/popcon.php?package=systemd [1]: https://packages.qa.debian.org/s/sysvinit/news/20131227T000039Z.html [2]: http://people.debian.org/~biebl/systemd-transition/init-system-helper-step1.diff [3]: http://people.debian.org/~biebl/systemd-transition/sysvinit.diff [4]: http://people.debian.org/~biebl/systemd-transition/init-system-helper-step2.diff [5]: http://people.debian.org/~biebl/systemd-transition/grub2.diff -- Michael Biebl and Tollef Fog Heen, on behalf of the systemd team -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/87mwc9gfsw....@xoog.err.no
