Re: upgrades must not change the installed init system [was: Re: Cinnamon environment now available in testing]

[Cameron Norman <camerontnorman@gmail.com>]

El lun, 8 de sep 2014 a las 9:07 , Matthias Urlichs <matthias@urlichs.de> escribió:

Hi, Vincent Danjean:

If I recall correctly, when Debian switched the default MTA, upgrades did not change the already installed.

You cannot have an MTA without configuring it, and nobody even tried to implement auto-migration of the old default mailer's configuration to the new one. Also, we didn't switch to a different default mailer because the new one offered a heap of features and infrastructure which the other lacked. None of this applies to systemd.

I do not think that the reasons for switching are at all relevant. These examples are unanimously pointing to defaults only being defaults for new installation.

I think most people would expect that if XFCE remained the default desktop for Jessie, then GNOME users should not be switched over without even being asked. But this is not even a good example. What we are doing here is switching **everyone**, even those who are using a custom /sbin/init in their own repo or Upstart.

Furthermore, this switching is being done far more often than just at upgrade time: everytime a user installs something that depends or recommends libpam-systemd (indirectly or directly), he or she currently have to double check that their init system is not being switched out from under them. Install CUPS? Better know that you have to install systemd-shim if you want to keep your init system...

The fact is that most "defaults" changes do not modify current user's systems (MTA, syslog, desktop environment), and they definitely do not do so without asking about it first (see /bin/dash).

Even if you do want to change it at upgrade time silently, the systemd-sysv | systemd-shim bit does way more than that, and it does so constantly and without any immediate guidance (i.e. install systemd-shim).

A couple ways to make this better would be to add a message in systemd-sysv saying that the system is being switched over (and that installing systemd-shim may prevent this, at the cost of a less complete/solid/whatever logind implementation), just switching the dependencies around, or using virtual packages for logind dependencies (since apt knows what is the best decision already).

Please consider the above prospective actions, and give feedback or results.

Thank you for your time and effort,

--

Cameron Norman