Re: Linuxisms in s6

[Warner Losh <imp@bsdimp.com>]

On Thu, Aug 25, 2016 at 3:08 PM, Adrian Chadd <adrian@freebsd.org> wrote:
> On 25 August 2016 at 12:48, Lars Engels <lars.engels@0x20.net> wrote:
>> On Thu, Aug 25, 2016 at 08:46:10AM -0700, Adrian Chadd wrote:
>>> On 24 August 2016 at 21:53, Jonathan de Boyne Pollard
>>> <J.deBoynePollard-newsgroups@ntlworld.com> wrote:
>>> > http://adrianchadd.blogspot.co.uk/2016/08/freebsd-on-tiny-system-whats-missing.html?showComment=1471236502051#c1305086913155850955
>>> > , Adrian Chadd:
>>> >
>>> >> We're using s6 at work, and it works out mostly ok. Mostly once you get
>>> >> around the linuxisms, and the lack of sensible time code in it (its
>>> >> calculations for daemon run duration is based on system time, not wall
>>> >> clock, so if your box boots jan 1, 1970 then gets NTP, things are..
>>> >> hilarious), and some of the arcane bits to get logging working right.
>>> >>
>>> > What are these Linuxisms in s6?  s6-linux-utils and s6-linux-init have
>>> > Linuxisms, obviously.  But what Linuxisms does s6 have?
>>>
>>> We just had a bunch of fun trying to get it to build right, and the
>>> uptime stuff really threw us.
>>>
>>> It's fine though, I found that s6 may start growing an IPC mechanism
>>> so we could possibly do a launchd/jobd style service later (ie to run
>>> things upon event changes, like ifup, ifdown, ifcreate, ifdestroy,
>>> arbitrary messages, etc) so I may try incorporating it again. :)
>>>
>>
>> Can't this be done with devd?
>
> Sure, but I'm looking for something more generic than just devd. Like,
> notifications about events like "default route is up" can be done by
> sniffing the rtsock, but notifications like "ntpdate has updated the
> date, we can now do crypto services" doesn't happen there right now.

devd was never intended to be limited to just device events from the
kernel. It has grown beyond that, and could easily grow to cope with
routing events and other notifications. No need to reinvent everything
for that.

What devd doesn't do is launchd / job control. That would be a whole
new kettle of fish for it, and one for which it may be ill suited. Though
viewed in the right way, it's all just a series of notifications: This service
is up, this is down, user wants to start this other one, etc, so maybe
it wouldn't so bad...

Warner
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