Re: s6 as a systemd alternative

From: Istvan Szukacs <>
Date: Mon, 26 Jun 2017 17:21:24 +0200

Hi Laurent,

First and foremost, thank you for working on s6! I see your point about the
drop-in replacement. I was not familiar with the efforts of uselessd. It
seems I am not the first one trying to have a usable system without
systemd. :) If I understand your suggestion correctly you are thinking
about having s6 as the init and using s6-rc for running the services. Would
this approach keep systemd installed just to provide for services directly
depending on it?

# rpm -q --requires openssh-server | grep systemd | sort -u

I am not sure why any service would depend on these. Is there functionality
in that an ssh service actually needs?


On Mon, Jun 26, 2017 at 4:48 PM, Laurent Bercot <
> wrote:

> I have a crazy question about s6. Would it be possible to make systemd
>> compatible?
> It all depends on what you mean by "compatible".
> There will never be full drop-in compatibility, because only systemd
> can be drop-in compatible with systemd. It has been designed this way,
> its architecture is a way of ensuring vendor lock-in. The most
> successful "compatible systemd replacement" so far was uselessd, and
> its author decided to put an end to the project when they realized how
> infeasible, and pointless, the work was: when you follow the systemd
> architecture, you end up with systemd, no way around it.
> What *would be* feasible, on the other hand, is a conversion tool
> from systemd unit files to a s6 + s6-rc database. It is still a lot
> of work, especially if one wants to implement all the systemd
> idiosyncrasies, but it is doable. I can't guarantee the output of
> such a conversion tool would be 100% compatible with the observed
> behaviour under systemd (in particular, bug-compatibility would not
> be ensured ;)) but it could probably be made to be close. nosh
> already has such a converter; I haven't tested it.
> I am currently thinking of implementing a file format for
> s6 + s6-rc + s6-linux-init service definition, in order to make it
> easier for people used to OpenRC or systemd to implement services
> with s6. This format probably cannot be systemd unit files, because
> unit files follow the systemd architecture too closely; but it could
> be a first step to a systemd-to-s6 conversion tool.
> - the previous alternatives all failed to gain traction because there was
>> too much effort to change systems around to use them
> That's not an argument, especially given the following one:
> - there is already too much effort went into systemd
> If people actually did the effort to write systemd unit files, there
> is no reason why they can't do the effort to write service definitions
> under a better format in order to have a better init system. The format
> just needs to be friendlier than what the current s6 suite provides.
> Working on conversion tools is currently my priority with s6. As usual,
> the limitation is my available free time.
> --
> Laurent

*Istvan Szukacs*
+31647081521 <//+31647081521>
+36 70 229 20 59 <http://+36702292059/>
Received on Mon Jun 26 2017 - 15:21:24 UTC

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