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Systemd services (was Re: If Linux Is About Choice, Why Then ...)

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  Systemd services (was Re: If Linux Is About Choice, Why Then ...) Jonathan de Boyne Pollard <j.deboynepollard-newsgroups@ntlworld.com> - 2017-04-13 23:20 +0200
    Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Greg Wooledge <wooledg@eeg.ccf.org> - 2017-04-14 15:00 +0200
      Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Nicolas George <george@nsup.org> - 2017-04-14 15:40 +0200
        Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Dejan Jocic <jodejka@gmail.com> - 2017-04-14 16:10 +0200
        Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Greg Wooledge <wooledg@eeg.ccf.org> - 2017-04-14 16:20 +0200
          Re: Re: Systemd services (was Re: If Linux Is About Choice, Why Then  ...) Laurent Bigonville <bigon@debian.org> - 2017-04-17 00:30 +0200
        Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Martin Read <zen75502@zen.co.uk> - 2017-04-14 17:40 +0200
        Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Jonathan Dowland <jmtd@debian.org> - 2017-04-18 00:10 +0200
          Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Nicholas Geovanis <nickgeovanis@gmail.com> - 2017-04-21 21:40 +0200
            Fwd: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Joel Rees <joel.rees@gmail.com> - 2017-04-22 01:10 +0200
      Re: Systemd services Teemu Likonen <tlikonen@iki.fi> - 2017-04-14 18:10 +0200
      Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...) Joel Rees <joel.rees@gmail.com> - 2017-04-15 00:40 +0200

#180108 — Systemd services (was Re: If Linux Is About Choice, Why Then ...)

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Greg Wooledge:

> 
>     Suppose you want to start DJB's daemontools from a locally created systemd
> unit/service. Here's a file that will do that:
> 

... albeit poorly.  If one wants to run daemontools under systemd, svscanboot is
not the way; svscanboot is a thing of the past
http://jdebp.eu./FGA/inittab-is-history.html#svscanboot , and was a source of
problems long before systemd was invented.


Greg Wooledge:

> 
>     (The Linux kernel introduced an entirely new thing called a "cgroup" to
> make this possible. That's how ridiculous self-backgrounding is.)
> 

Control groups are not jobs
http://jdebp.eu./FGA/linux-control-groups-are-not-jobs.html ; they were
introduced to do resource limiting, and the systemd developers have actually
complained quite a lot over the years that control groups did not turn out to be
what they thought they were.


Greg Wooledge:

> 
>     $ systemctl status daemontools.service
> 
>     * daemontools.service – daemontools supervisor
>     Loaded: loaded (/etc/systemd/system/daemontools.service; enabled)
>     Active: active (running) since Wed 2017-01-11 03:28:47 EST; 2 months 21
> days ago
>     Main PID: 529 (svscanboot)
>     CGroup: /system.slice/daemontools.service
>     |- 529 /bin/sh /command/svscanboot /dev/ttyS0
>     |- 531 svscan /service
> 

... and there is svscanboot being a problem again.  Notice how the main PID is
wrong, and the log output from svscan (when there is some) does not go into the
log that systemctl shows below this.


Greg Wooledge:

> 
>     if you want to change the behavior of the Debian default getty@ service to
> make it stop clearing the screen all the damned time,
> 

The world wants you to clean your screen
http://unix.stackexchange.com/a/233855/5132 , and this is merely one of the ways
that it makes you do so.

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#180127

On Thu, Apr 13, 2017 at 10:01:25PM +0100, Jonathan de Boyne Pollard wrote:
> ... albeit poorly.  If one wants to run daemontools under systemd, svscanboot is
> not the way; svscanboot is a thing of the past
> http://jdebp.eu./FGA/inittab-is-history.html#svscanboot , and was a source of
> problems long before systemd was invented.

Cool.  I wish my Google searching had stumbled upon that, when I was
trying to figure out how to do all that stuff.

> The world wants you to clean your screen
> http://unix.stackexchange.com/a/233855/5132 , and this is merely one of the ways
> that it makes you do so.

Some day there will be actual end-user-friendly systemd documentation
somewhere, consolidating all of these pieces of wisdom together.  I hope.

My own contributions toward that effort have been riddled with failure and
confusion, for which I am sorry.  I'm honestly *trying*, but this stuff is
really opaque at times.

For instance, just this week I learned three new things:

1) To override parts of a distribution's systemd unit locally, you MUST
   use the foo.service.d/ method.  You can't just put the override bits
   into an /etc/systemd/system/foo.service file.  That would be too easy.

2) The files inside foo.service.d/ MUST end with a .conf suffix.  (Cf.
   the wheezy->jessie apache2 upgrade, and having to rename every single
   one of my virtual domain config files AND the symlinks to them.)

3) foo.service.d/ must use the CANONICAL service name of whatever it is
   that you're trying to override.  This may not be the same as the
   Debian package name.  For example, the nfs-kernel-server package
   creates a systemd unit named nfs-server.service with an ALIAS of
   nfs-kernel-server.service.  If you try to create override files in
   nfs-kernel-server.service.d/ it will not work correctly.  They have
   to be in nfs-server.service.d/ instead.

   Don't even get me started on sshd.service vs. ssh.service.  Do you
   have any idea how hard it is to notice that extra/missing "d", and
   figure out why things Simply Do Not Work?

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#180130

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Le quintidi 25 germinal, an CCXXV, Greg Wooledge a écrit :
> Some day there will be actual end-user-friendly systemd documentation
> somewhere, consolidating all of these pieces of wisdom together.  I hope.

Note: systemd is not for end-users, it is for system administrator and
distribution authors.

> 1) To override parts of a distribution's systemd unit locally, you MUST
>    use the foo.service.d/ method.  You can't just put the override bits
>    into an /etc/systemd/system/foo.service file.  That would be too easy.

foo.service.d/*.conf            is for overriding bits.
/etc/systemd/system/foo.service is for overriding the whole file.

I find that fairly natural. Otherwise, how would you override the whole
file?

> 2) The files inside foo.service.d/ MUST end with a .conf suffix.  (Cf.
>    the wheezy->jessie apache2 upgrade, and having to rename every single
>    one of my virtual domain config files AND the symlinks to them.)

After having been bitten by old *.conf~ backup files left by an editor,
I must say I find that restriction quite useful.

> 3) foo.service.d/ must use the CANONICAL service name of whatever it is
>    that you're trying to override.  This may not be the same as the
>    Debian package name.  For example, the nfs-kernel-server package
>    creates a systemd unit named nfs-server.service with an ALIAS of
>    nfs-kernel-server.service.  If you try to create override files in
>    nfs-kernel-server.service.d/ it will not work correctly.  They have
>    to be in nfs-server.service.d/ instead.
> 
>    Don't even get me started on sshd.service vs. ssh.service.  Do you
>    have any idea how hard it is to notice that extra/missing "d", and
>    figure out why things Simply Do Not Work?

On the other hand, if systemd were to read snippets of configuration
with a subtly different name, someone else (or maybe be even yourself!)
would have complained about wasted time because of a stale config
snippet that should not have been read.

I find that strict rules are usually more convenient in the long run.

Note that you can use "systemctl edit" to have an editor started on the
exact correct file.

Regards,

-- 
  Nicolas George

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#180131

On 14-04-17, Nicolas George wrote:
> Le quintidi 25 germinal, an CCXXV, Greg Wooledge a écrit :
> > Some day there will be actual end-user-friendly systemd documentation
> > somewhere, consolidating all of these pieces of wisdom together.  I hope.
> 
> Note: systemd is not for end-users, it is for system administrator and
> distribution authors.
> 
Actually, it should be for end-user too. On personal computer, that
end-user is system administrator. I also find that systemd is very well
documented. But it could be just me. Now, please carry on, enjoyed this
thread very much, learned thing, or two :)

Thank you for your time.

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#180132

On Fri, Apr 14, 2017 at 03:17:00PM +0200, Nicolas George wrote:
> Le quintidi 25 germinal, an CCXXV, Greg Wooledge a écrit :
> > Some day there will be actual end-user-friendly systemd documentation
> > somewhere, consolidating all of these pieces of wisdom together.  I hope.
> 
> Note: systemd is not for end-users, it is for system administrator and
> distribution authors.

The end users of systemd are Linux system administrators.  You and me.
The people on this mailing list.  That's us, the users.  That's why
it's called "debian-user".

If you'd prefer "Some day there will be a system administrator's guide
for systemd", that's an acceptable wording.

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#180199 — Re: Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...)

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Greg Wooledge <wooledg@eeg.ccf.org <mailto:wooledg%40eeg.ccf.org>> wrote:
> On Fri, Apr 14, 2017 at 03:17:00PM +0200, Nicolas George wrote:
> > Le quintidi 25 germinal, an CCXXV, Greg Wooledge a écrit :
> > > Some day there will be actual end-user-friendly systemd documentation
> > > somewhere, consolidating all of these pieces of wisdom together.  I hope.
> >
> > Note: systemd is not for end-users, it is for system administrator and
> > distribution authors.
>
> The end users of systemd are Linux system administrators.  You and me.
> The people on this mailing list.  That's us, the users.  That's why
> it's called "debian-user".
>
> If you'd prefer "Some day there will be a system administrator's guide
> for systemd", that's an acceptable wording.
There is already extensive documentation about how to administrate systemd:

https://www.freedesktop.org/wiki/Software/systemd/#manualsanddocumentationforusersandadministrators

"The systemd for Administrators Blog Series" worth reading.

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#180133

On 14/04/17 14:17, Nicolas George wrote:
> Le quintidi 25 germinal, an CCXXV, Greg Wooledge a écrit :
>> Some day there will be actual end-user-friendly systemd documentation
>> somewhere, consolidating all of these pieces of wisdom together.  I hope.
>
> Note: systemd is not for end-users, it is for system administrator and
> distribution authors.

systemd is absolutely for end-users, because:

* Some systemd-running systems are home desktop computers with a single 
physical user; in this case, the distinction between "administrator" and 
"user" may well only exist as a hallucination of the computer, with no 
basis in the external physical world. If the computer I'm typing this 
e-mail on breaks down, I have to fix it myself.

* systemd can, in any event, be used to manage service-like processes 
that form part of a user's login session, using unit files stored in 
that user's XDG Base Directories.

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#180231

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On Fri, Apr 14, 2017 at 03:17:00PM +0200, Nicolas George wrote:
> Note: systemd is not for end-users, it is for system administrator and
> distribution authors.

{systemctl,journalctl,etc.} --user beg to differ.


-- 
⢀⣴⠾⠻⢶⣦⠀ 
⣾⠁⢠⠒⠀⣿⡁ Jonathan Dowland
⢿⡄⠘⠷⠚⠋⠀ https://jmtd.net
⠈⠳⣄⠀⠀⠀⠀ Please do not CC me, I am subscribed to the list.

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#180374

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Like numerous linux users I have sometimes lamented coming to terms with
systemd. My belief is that it's a well-written collection of software which
is somewhat over-engineered. It fills a need, sure, though I've managed to
live and work without it for a long time (been using linux since 1994). And
who am I to question Torvalds and Co. on the subject of its suitability for
linux and the data center?

So the other day I was on a recently-built Amazon AWS EC2 instance, running
one of the AWS-branded linux AMIs, fixing things in /etc/init.d. Thinking
about how AWS might rule the world someday, since they already hold about
35-40% of the public cloud (
http://www.geekwire.com/2017/cloud-report-card-amazon-web-services-12b-juggernaut-microsoft-google-gaining/).
Then I had one of those "Duh!" moments: There must be on-the-order-of a
million of linux instances on the planet which are _not_ running systemd,
as AWS's own linux AMIs do not by default.

It seems to me that this data point has been completely ignored in the
years-long discussions about systemd's merits, flaws and suitability.

On Mon, Apr 17, 2017 at 4:34 PM, Jonathan Dowland <jmtd@debian.org> wrote:

> On Fri, Apr 14, 2017 at 03:17:00PM +0200, Nicolas George wrote:
> > Note: systemd is not for end-users, it is for system administrator and
> > distribution authors.
>
> {systemctl,journalctl,etc.} --user beg to differ.
>
>
> --
> ⢀⣴⠾⠻⢶⣦⠀
> ⣾⠁⢠⠒⠀⣿⡁ Jonathan Dowland
> ⢿⡄⠘⠷⠚⠋⠀ https://jmtd.net
> ⠈⠳⣄⠀⠀⠀⠀ Please do not CC me, I am subscribed to the list.
>

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#180381

 On Sat, Apr 22, 2017 at 4:13 AM, Nicholas Geovanis
<nickgeovanis@gmail.com> wrote:
> Like numerous linux users I have sometimes lamented coming to terms with
> systemd. My belief is that it's a well-written collection of software which
> is somewhat over-engineered. It fills a need, sure, though I've managed to
> live and work without it for a long time (been using linux since 1994). And
> who am I to question Torvalds and Co. on the subject of its suitability for
> linux and the data center?

Have Linus and Lennart come to a meeting of minds or something?

So I looked up "Torvalds systemd" and found a slashdot Q/A article with
Torvalds in which someone asked him about systemd.

Interesting.

> So the other day I was on a recently-built Amazon AWS EC2 instance, running
> one of the AWS-branded linux AMIs, fixing things in /etc/init.d. Thinking
> about how AWS might rule the world someday, since they already hold about
> 35-40% of the public cloud
> (http://www.geekwire.com/2017/cloud-report-card-amazon-web-services-12b-juggernaut-microsoft-google-gaining/).
> Then I had one of those "Duh!" moments: There must be on-the-order-of a
> million of linux instances on the planet which are _not_ running systemd, as
> AWS's own linux AMIs do not by default.
>
> It seems to me that this data point has been completely ignored in the
> years-long discussions about systemd's merits, flaws and suitability.
>
> On Mon, Apr 17, 2017 at 4:34 PM, Jonathan Dowland <jmtd@debian.org> wrote:
>>
>> On Fri, Apr 14, 2017 at 03:17:00PM +0200, Nicolas George wrote:
>> > Note: systemd is not for end-users, it is for system administrator and
>> > distribution authors.
>>
>> {systemctl,journalctl,etc.} --user beg to differ.
>>
>>
>> --
>> ⢀⣴⠾⠻⢶⣦⠀
>> ⣾⠁⢠⠒⠀⣿⡁ Jonathan Dowland
>> ⢿⡄⠘⠷⠚⠋⠀ https://jmtd.net
>> ⠈⠳⣄⠀⠀⠀⠀ Please do not CC me, I am subscribed to the list.
>
>



--
Joel Rees

I'm imagining I'm a novelist:
http://joel-rees-economics.blogspot.com/2017/01/soc500-00-00-toc.html
More of my delusions:
http://reiisi.blogspot.jp/p/novels-i-am-writing.html


-- 
Joel Rees

I'm imagining I'm a novelist:
http://joel-rees-economics.blogspot.com/2017/01/soc500-00-00-toc.html
More of my delusions:
http://reiisi.blogspot.jp/p/novels-i-am-writing.html

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#180134 — Re: Systemd services

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Greg Wooledge [2017-04-14 08:37:55-04] wrote:

> Some day there will be actual end-user-friendly systemd documentation
> somewhere, consolidating all of these pieces of wisdom together. I
> hope.

I learnd by reading systemd's really good man pages:

    $ man systemd.unit
    $ man systemd.timer
    $ man systemd.service
    ...

And Linux system's are full of real unit file "examples" which can be
read with "systemctl cat foo.service".

-- 
/// Teemu Likonen   - .-..   <https://keybase.io/tlikonen> //
// PGP: 4E10 55DC 84E9 DFF6 13D7 8557 719D 69D3 2453 9450 ///

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#180146

On Fri, Apr 14, 2017 at 9:37 PM, Greg Wooledge <wooledg@eeg.ccf.org> wrote:
> [...]
>    Don't even get me started on sshd.service vs. ssh.service.  Do you
>    have any idea how hard it is to notice that extra/missing "d", and
>    figure out why things Simply Do Not Work?

Well, that demonstrates that the concept of tagging a "d" on the end
of a name to indicate the daemon part well predates systemd, and
probably should be reconsidered in a world where short names are no
longer required.

Not sure how that relates to the rest of the issues you are trying to
work through.

-- 
Joel Rees

I'm imagining I'm a novelist:
http://joel-rees-economics.blogspot.com/2017/01/soc500-00-00-toc.html
More of my delusions:
http://reiisi.blogspot.jp/p/novels-i-am-writing.html

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