[chiglug] systemd (Kirk Tolliver)

Wed Nov 11 15:31:37 UTC 2015

Hey,
Thanks for the insight into systemd. I am running some tests with runit and openrc against a Mint box.

Sent from [ProtonMail](https://protonmail.ch), encrypted email based in Switzerland.

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Subject: discuss Digest, Vol 17, Issue 8
Local Time: November 11 2015 6:00 am
UTC Time: November 11 2015 12:00 pm
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Today's Topics:

1. Re: systemd (Steve Litt)
2. Re: systemd (Derek Pressnall)
3. Re: systemd (William Giokas)

----------------------------------------------------------------------

Message: 1
Date: Tue, 10 Nov 2015 11:31:38 -0500
From: Steve Litt <slitt at troubleshooters.com>
To: chicagolug <discuss at lists.chicagolug.org>
Subject: Re: [chiglug] systemd
Message-ID: <20151110113138.4a57f6d5 at mydesk.domain.cxm>
Content-Type: text/plain; charset=US-ASCII

On Tue, 10 Nov 2015 16:00:54 +0000
Rob Dux <robwdux at gmail.com> wrote:

> I'd like to know where systemd shines i.e. what is the best
> application for systemd and my current belief is desktop.

Only to the extent that the Freedesktop project has dependencied their
stuff to the extent that it's hard to get working without systemd, and
of course Gnome doesn't work without systemd unless the distro
massively changes the Gnome code.

My Daily Driver Desktop, which I use 80% as a desktop and 20% as a
server, would gain no benefit from systemd, and instead inits with
Runit.

Offhand I can think of two use cases for systemd:

1) You need a lightning fast boot
2) You have a team of Unix-inexperienced technologists who would find
it easier to learn systemctl than to learn Unix.

> I interact
> with it in fedora and when I have to shell into servers that use it.
>
> We're adopting Docker at my employer for which I gave a talk last lug
> and there is a requirement for an init system in some applications for
> containers which I selected s6 for various reasons.

Nice! Please let me know how s6 works for you. The only stuff I've done
with s6 has been purely experimental. Have you tried s6-rc yet? I
haven't.

> As far as Docker
> hosts, Alpine Linux seems most ideal and it ships with OpenRC.

> In
> every case for our production needs, minimalism is the key.

OpenRC never struck me as minimal. It needs another PID1 (usually
sysvinit) to start up, and it can't respawn dead daemons, so to do so
you need either sysvinit on the PID1 end, or
daemontools/daemontools-encore on the other end.

SteveT

Steve Litt
November 2015 featured book: Troubleshooting Techniques
of the Successful Technologist
http://www.troubleshooters.com/techniques

------------------------------

Message: 2
Date: Tue, 10 Nov 2015 13:15:22 -0600
From: Derek Pressnall <derekp at needcaffeine.net>
Cc: discuss at lists.chicagolug.org
Subject: Re: [chiglug] systemd
Message-ID:
<CAEnESSkrE5dXhwWQnTRHHCh3mcNCjN6x4kafC5o287JtkPCM5Q at mail.gmail.com>
Content-Type: text/plain; charset=UTF-8

I really like systemd in general, but there are a few things that gets me:
1) It isn't as transparent as rc files
When there is a problem, you can't just turn on -xv in the bash
scripts to see what all is going on. And with the parallel startup
nature, it is hard to figure out which messages are related to a given
hang condition on startup. Of course, there are systemd-specific
commands that can be use to diagnose issues, but that is an additional
learning curve (traditionally, there was an easy transition from
normal Unix admin skills to Linux).

Here's a real-world example that I ran into recently: the system
(Fedora 22 I believe) hung up in the middle of shutdown, giving me no
option other than a hard power off. Apparently, I mounted a Windows
SMB file share manually, and systemd decided to cut the network off
before unmounting the share. So the shutdown hung. Now maybe I
should have added a line in /etc/fstab indicating this was a _netdev,
but I still should be able to temporarily mount a filesystem from the
command line.

2) Could systemd still do its magic if it wasn't PID 1? That is, keep
a very simple traditional init, which then launches systemd that would
then own the bulk of the other services. This would allow peace an
harmony between the old and new way of doing things. But then again,
I imagine that systemd wouldn't be as useful if there were other
processes running outside of it.

Now, something I'd like to see added (if it can be done with the
existing systemd framework): Could systemd intercept a console key
combination that brings up a (password-protected) rescue environment?
That way if there is a problem on startup or shutdown, this can be
used to at least help diagnose the issue. The environment could be a
command shell with all the busybox commands pre-linked into it (so
that it wouldn't even require a mounted root image).

On Mon, Nov 9, 2015 at 9:01 AM, sten <me at sud0.com> wrote:
> Hey,
>
> So I'm trying to put together a presentation about systemd for people who
> have decided they have some sort of problem with systemd. I'd love for it to
> be conversational styled - me and someone (or someones) who wants to talk in
> front of people in favor of sysvinit or a different alternative.
>
> I talked to a couple folks 2 meetings ago, but I may have been overly
> confrontational about it, and I really want to hear what objections still
> remain.
>
> Drop me a note on- or off-list, let's see if we can come up with something
> together.
>
> -sten
>
>
> _______________________________________________
> discuss mailing list
> discuss at lists.chicagolug.org
> https://lists.chicagolug.org/mailman/listinfo/discuss
>

------------------------------

Message: 3
Date: Tue, 10 Nov 2015 11:27:39 -0800
From: William Giokas <1007380 at gmail.com>
To: Derek Pressnall <derekp at needcaffeine.net>
Cc: discuss at lists.chicagolug.org
Subject: Re: [chiglug] systemd
Message-ID:
<CAEAHfPB7Gu8f-PYPencPirfMDHNYzDU8hO2XF+jgKrRGGixQLA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

About 1, I would disagree. An rc file can have any scripting language the
author can rely on to be on the system (zhs, bash, sh, perl, etc.), there's
no standardized options. Does init script x fork the exact same way as y?
They could be in written very differently. When systemd services are looked
at, either at the file or with systemctl show, the options are all listed.

Also, while looking at a shell script may be second nature to users like
us, to newer or less experienced users, and not importantly machines,
systemd services are vastly easier to parse. Certain things can't be
achieved through the options systemd gives you, but then at that point you
can just use an initscript in systemd, if need be.

Bill Giokas
http://kaictl.net/
On Nov 10, 2015 1:15 PM, "Derek Pressnall" <derekp at needcaffeine.net> wrote:

> I really like systemd in general, but there are a few things that gets me:
> 1) It isn't as transparent as rc files
> When there is a problem, you can't just turn on -xv in the bash
> scripts to see what all is going on. And with the parallel startup
> nature, it is hard to figure out which messages are related to a given
> hang condition on startup. Of course, there are systemd-specific
> commands that can be use to diagnose issues, but that is an additional
> learning curve (traditionally, there was an easy transition from
> normal Unix admin skills to Linux).
>
> Here's a real-world example that I ran into recently: the system
> (Fedora 22 I believe) hung up in the middle of shutdown, giving me no
> option other than a hard power off. Apparently, I mounted a Windows
> SMB file share manually, and systemd decided to cut the network off
> before unmounting the share. So the shutdown hung. Now maybe I
> should have added a line in /etc/fstab indicating this was a _netdev,
> but I still should be able to temporarily mount a filesystem from the
> command line.
>
> 2) Could systemd still do its magic if it wasn't PID 1? That is, keep
> a very simple traditional init, which then launches systemd that would
> then own the bulk of the other services. This would allow peace an
> harmony between the old and new way of doing things. But then again,
> I imagine that systemd wouldn't be as useful if there were other
> processes running outside of it.
>
> Now, something I'd like to see added (if it can be done with the
> existing systemd framework): Could systemd intercept a console key
> combination that brings up a (password-protected) rescue environment?
> That way if there is a problem on startup or shutdown, this can be
> used to at least help diagnose the issue. The environment could be a
> command shell with all the busybox commands pre-linked into it (so
> that it wouldn't even require a mounted root image).
>
> On Mon, Nov 9, 2015 at 9:01 AM, sten <me at sud0.com> wrote:
> > Hey,
> >
> > So I'm trying to put together a presentation about systemd for people who
> > have decided they have some sort of problem with systemd. I'd love for
> it to
> > be conversational styled - me and someone (or someones) who wants to
> talk in
> > front of people in favor of sysvinit or a different alternative.
> >
> > I talked to a couple folks 2 meetings ago, but I may have been overly
> > confrontational about it, and I really want to hear what objections still
> > remain.
> >
> > Drop me a note on- or off-list, let's see if we can come up with
> something
> > together.
> >
> > -sten
> >
> >
> > _______________________________________________
> > discuss mailing list
> > discuss at lists.chicagolug.org
> > https://lists.chicagolug.org/mailman/listinfo/discuss
> >
>
> _______________________________________________
> discuss mailing list
> discuss at lists.chicagolug.org
> https://lists.chicagolug.org/mailman/listinfo/discuss
>
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