Re: Clarifying what 'systemd' actually means

[Alessandro Vesely <vesely@tana.it>]

On Sun 02/Jul/2017 12:37:33 +0200 Christian Seiler wrote:
> On 07/02/2017 11:24 AM, Michael Fothergill wrote:
>> ​Could this be exploited to force people to use sysvinit instead of systemd ?

:-)

> This bug has nothing to do with systemd as the init system, it's in an
> optional component that's disabled by default on Debian. In principle,
> I suspect that resolved could also be used on sysvinit, if you really
> wanted to, though I haven't tried it.
> 
> Furthermore, the systemd versions of Wheezy and Jessie are too old to
> already include systemd-resolved, so they are not affected at all.

Yet, there's a man page:
https://manpages.debian.org/jessie/systemd/systemd-resolved.service.8.en.html


> In general, I think it's helpful for everyone to take a mental note
> that 'systemd' can mean two things:
> 
>  1. The init binary itself. (PID 1)
> 
>  2. A project that implements various things in userspace
>     that includes the init binary, but also an assortment
>     of other tools.
> 
> In fact, it might be very helpful to draw the following Venn diagram:
> 
> +---------------------------------------------------------------------+
> |                          systemd project                            |
> |                                                                     |
> | +----------------------------+ +----------------------------------+ |
> | |  init system               | |  other tools (some require that  | |
> | |                            | |  systemd be PID1, others don't)  | |
> | | +------------------------+ | |                                  | |
> | | | systemd binary (PID 1) | | |  these are all optional when     | |
> | | +------------------------+ | |  using systemd as init system,   | |
> | |                            | |  and there are other projects    | |
> | | +------------------------+ | |  providing similar functionality | |
> | | | generators             | | |                                  | |
> | | | (for supporing         | | | +------------------------------+ | |
> | | | /etc/fstab, etc.)      | | | | resolved                     | | |
> | | +------------------------+ | | +------------------------------+ | |
> | | [...]

I'd be curious on why tools which don't even require that systemd be PID1 go
under the systemd umbrella.  Doesn't that contribute to make systemd appear
like some kind of conspiracy?

BTW, is resolved one of them or does it require systemd?

Ale