Which init system for Debian?

Posted Feb 4, 2014 23:34 UTC (Tue) by anselm (subscriber, #2796)
In reply to: Which init system for Debian? by foom
Parent article: Which init system for Debian?

And that Debian isn't afraid to do something that is different than others if it makes sense.

Debian picked Exim as the default MTA before Postfix was ready for prime time, and then never bothered to change again. After all, Exim is perfectly adequate for many applications, and it is trivial to replace it with Postfix (or indeed some other MTA such as Sendmail, qmail, or Courier, all of which are packaged for Debian) if that's desired,

It is fairly safe to say that had Postfix been usable at the time, Debian would have gone with it as the default MTA instead of Exim.

Which init system for Debian?

Posted Feb 5, 2014 1:32 UTC (Wed) by foom (subscriber, #14868) [Link] (6 responses)

Exim seems superior to postfix in most ways, despite postfix being more popular.

I know others disagree, but how is the decision *obviously* postfix, even today?

Which init system for Debian?

Posted Feb 5, 2014 22:16 UTC (Wed) by smurf (subscriber, #17840) [Link] (5 responses)

It's not. You can easily run a large email site with Exim.

Anyway, this comparison is moot. Both deliver email quite well, that's all they do and that's all they're supposed to do. Thus, this is not at all related to the systemd vs. upstart debate.

Which init system for Debian?

Posted Feb 5, 2014 22:58 UTC (Wed) by hummassa (subscriber, #307) [Link] (4 responses)

Nah, I don't think so. Exim and postfix and qmail etc. *do* have subtle differences.

And if some package needs not only a mailer, but -- for instance -- qmail, it's a matter just of packaging it depending on qmail specifically.

The same applies between systemd and upstart. The service files are automatically translatable between them (and openrc and sysvinit). If any package *needs* a specific one, it should just depend on this one. The package can even indicate its *preference* for one of them by way of
"Recommends:". No difference.

Which init system for Debian?

Posted Feb 6, 2014 1:08 UTC (Thu) by vonbrand (subscriber, #4458) [Link] (3 responses)

No, the configuration files certainly aren't translatable. Yes, upstart and systemd can run SysVinit scripts though the shell as a fallback. But native upstart (or systemd, for that matter) configurations express stuff that just can't be done in SysVinit (that is sort of the point of replacing SysVinit). In upstart dependencies are described by events, would need to untengle the whole "who triggers what" dependencies of the complete set to sort them into runlevels to get some approximation in SysVinit, and that would just go back to "cross fingers that the requisite stuff is already available" mantra. Systemd starts services mostly on demand, with some hand-configured dependencies. The dependencies could be sorted into runlevels, the "on first access" part definitively not. And the underlying models of upstart and systemd are too different for interoperation (systemd started precisely from scratch to solve fundamental problems with upstart's model).

Which init system for Debian?

Posted Feb 6, 2014 9:56 UTC (Thu) by hummassa (subscriber, #307) [Link] (2 responses)

If the most complete model is systemd's (and, in my assessment of the four init systems, yes it is), it is possible to emulate the same model (even if not perfectly) on the other init systems -- and at least the "systemd to upstart", "systemd to sysv", "systemd to openrc" are automatable or semi-automatable. Annotations could be done in comments in the systemd service files to help the "semi-" part.

Which init system for Debian?

Posted Feb 8, 2014 22:27 UTC (Sat) by smurf (subscriber, #17840) [Link] (1 responses)

Huh? If systemd can do everything the others can, then in theory the other config files can be translated to systemd, but not vice versa.

This is nontrivial even for shell scripts and would be a total mess to automate for upstart because systemd does not have (nor need) an event concept the way upstart has.

You can of course annotate a sysVinit or upstart script so that systemd can auto-translate it. But then you can write a systemd unit file from scratch just as easily, so why bother?

Which init system for Debian?

Posted Feb 8, 2014 22:52 UTC (Sat) by vonbrand (subscriber, #4458) [Link]

Both upstart and systemd can run SysVinit scripts for backward compatibility, so that point is moot.