reconfiguring

reconfiguring

[Catonano]

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About

guix system reconfigue some/conf-file.scm

I read in the manual that

"The command starts system services specified in file that are not
currently running; if a service is currently running, it does not attempt
to upgrade it since this would not be possible without stopping it first."

I was wondering: what about the desktop services ?

I undertsand that my desktop session comes with a few services (in
%desktop-services or something)

Does this mean that my desktop services do NOT get updated when I
reconfigure my system ?

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Re: reconfiguring

[Ricardo Wurmus]

Catonano <catonano@gmail.com> writes:

> "The command starts system services specified in file that are not
> currently running; if a service is currently running, it does not attempt
> to upgrade it since this would not be possible without stopping it first."
>
> I was wondering: what about the desktop services ?
>
> I undertsand that my desktop session comes with a few services (in
> %desktop-services or something)
>
> Does this mean that my desktop services do NOT get updated when I
> reconfigure my system ?

That’s a misunderstanding.  All of the things in the “services” field of
your operating-system configuration are “system services”, so all of
them get updated.

-- 
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net

Re: reconfiguring

[Leo Famulari]

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On Tue, Feb 13, 2018 at 07:25:10PM +0100, Ricardo Wurmus wrote:
> 
> Catonano <catonano@gmail.com> writes:
> 
> > "The command starts system services specified in file that are not
> > currently running; if a service is currently running, it does not attempt
> > to upgrade it since this would not be possible without stopping it first."
> >
> > I was wondering: what about the desktop services ?
> >
> > I undertsand that my desktop session comes with a few services (in
> > %desktop-services or something)
> >
> > Does this mean that my desktop services do NOT get updated when I
> > reconfigure my system ?
> 
> That’s a misunderstanding.  All of the things in the “services” field of
> your operating-system configuration are “system services”, so all of
> them get updated.

But, it doesn't try to stop and restart those services in case of any
relevant changes, right? Doesn't that require a reboot?

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Re: reconfiguring

[Ricardo Wurmus]

Leo Famulari <leo@famulari.name> writes:

> But, it doesn't try to stop and restart those services in case of any
> relevant changes, right? Doesn't that require a reboot?

Correct.  The manual says:

  "The command starts system services specified in file that are not
   currently running; if a service is currently running, it does not
   attempt to upgrade it since this would not be possible without
   stopping it first."

--
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net

Re: reconfiguring

[Carlo Zancanaro]

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On Tue, Feb 13 2018, Leo Famulari wrote:
>> That’s a misunderstanding.  All of the things in the “services” 
>> field of
>> your operating-system configuration are “system services”, so 
>> all of
>> them get updated.
>
> But, it doesn't try to stop and restart those services in case 
> of any
> relevant changes, right? Doesn't that require a reboot?

The "system services" aren't services in the sense of being 
started/stopped. They are an extensible way to modify the system, 
such that one "service" can depend on another for its behaviour. 
For example, the `etc-service-type` is responsible for putting 
files in /etc, and so other services can "extend" it with files 
that they want placed in /etc. The concept of "starting" and 
"stopping" these services isn't really meaningful, because they 
just specify the state of the system. These services have an 
effect when you reconfigure.

One of the things that a "system service" can do is to register a 
Shepherd service. This is a process which will be invoked by 
Shepherd (pid 1), and can be started/stopped with the `herd` 
command. Reconfigure will not register any new Shepherd services, 
if doing so would involve starting an already-running service. So, 
for instance, you probably have a `guix-daemon` process running on 
your system. Reconfiguring your system will not upgrade (and thus 
restart) your `guix-daemon`. You need to reboot to have the new, 
updated, `guix-daemon` process. (Ideally you would only have to 
stop/start the Shepherd service manually to have the updated 
version, but at the moment doing so will just restart the old 
version.)

Hopefully that explanation is helpful. I also hope it's correct.

Carlo

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Re: reconfiguring

[Leo Famulari]

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On Wed, Feb 14, 2018 at 06:18:07AM +1100, Carlo Zancanaro wrote:
> 
> On Tue, Feb 13 2018, Leo Famulari wrote:
> > > That’s a misunderstanding.  All of the things in the “services”
> > > field of
> > > your operating-system configuration are “system services”, so all of
> > > them get updated.
> > 
> > But, it doesn't try to stop and restart those services in case of any
> > relevant changes, right? Doesn't that require a reboot?
> 
> The "system services" aren't services in the sense of being started/stopped.
> They are an extensible way to modify the system, such that one "service" can
> depend on another for its behaviour. For example, the `etc-service-type` is
> responsible for putting files in /etc, and so other services can "extend" it
> with files that they want placed in /etc. The concept of "starting" and
> "stopping" these services isn't really meaningful, because they just specify
> the state of the system. These services have an effect when you reconfigure.
> 
> One of the things that a "system service" can do is to register a Shepherd
> service. This is a process which will be invoked by Shepherd (pid 1), and
> can be started/stopped with the `herd` command. Reconfigure will not
> register any new Shepherd services, if doing so would involve starting an
> already-running service. So, for instance, you probably have a `guix-daemon`
> process running on your system. Reconfiguring your system will not upgrade
> (and thus restart) your `guix-daemon`. You need to reboot to have the new,
> updated, `guix-daemon` process. (Ideally you would only have to stop/start
> the Shepherd service manually to have the updated version, but at the moment
> doing so will just restart the old version.)
> 
> Hopefully that explanation is helpful. I also hope it's correct.

Thanks, that's a very helpful explanation!

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Re: reconfiguring

[Andreas Enge]

On Tue, Feb 13, 2018 at 02:03:58PM -0500, Leo Famulari wrote:
> But, it doesn't try to stop and restart those services in case of any
> relevant changes, right? Doesn't that require a reboot?

Yes, I understood so. I had the problem with my nginx server recently.
In that case, I needed to stop it before upgrading, and then it was
restarted automatically. However, when it was not stopped, it continued
running with the old configuration. It is not quite clear to me whether
this is a bug or a feature. I tend more towards bug... It is definitely
in contrast to what happens in Debian, for instance.

Andreas

Re: reconfiguring

[myglc2]

On 02/13/2018 at 21:32 Andreas Enge writes:

> On Tue, Feb 13, 2018 at 02:03:58PM -0500, Leo Famulari wrote:
>> But, it doesn't try to stop and restart those services in case of any
>> relevant changes, right? Doesn't that require a reboot?
>
> Yes, I understood so. I had the problem with my nginx server recently.
> In that case, I needed to stop it before upgrading, and then it was
> restarted automatically. However, when it was not stopped, it continued
> running with the old configuration. It is not quite clear to me whether
> this is a bug or a feature. I tend more towards bug... It is definitely
> in contrast to what happens in Debian, for instance.

This bug/feature bit me (also Debian user) recently ;-)

Is this by design? Or a limitation if the current implementation?

Re: reconfiguring

[Ricardo Wurmus]

myglc2@gmail.com writes:

> On 02/13/2018 at 21:32 Andreas Enge writes:
>
>> On Tue, Feb 13, 2018 at 02:03:58PM -0500, Leo Famulari wrote:
>>> But, it doesn't try to stop and restart those services in case of any
>>> relevant changes, right? Doesn't that require a reboot?
>>
>> Yes, I understood so. I had the problem with my nginx server recently.
>> In that case, I needed to stop it before upgrading, and then it was
>> restarted automatically. However, when it was not stopped, it continued
>> running with the old configuration. It is not quite clear to me whether
>> this is a bug or a feature. I tend more towards bug... It is definitely
>> in contrast to what happens in Debian, for instance.
>
> This bug/feature bit me (also Debian user) recently ;-)
>
> Is this by design? Or a limitation if the current implementation?

It’s a bug; bug 22039 to be exact.

-- 
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net

Re: reconfiguring

[Carlo Zancanaro]

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On Tue, Feb 13 2018, Ricardo Wurmus wrote:
> That’s a misunderstanding.  All of the things in the “services” 
> field of
> your operating-system configuration are “system services”, so 
> all of
> them get updated.

Should we think about changing the name for "system services"? The 
confusion with Shepherd services seems really easy to make. The 
Wikipedia article for GuixSD makes the same mistake, but I haven't 
had the chance to fix it yet. Maybe we should call them "system 
extensions", or "mixins", or something like that?

Carlo

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Re: reconfiguring

[Ricardo Wurmus]

Carlo Zancanaro <carlo@zancanaro.id.au> writes:

> On Tue, Feb 13 2018, Ricardo Wurmus wrote:
>> That’s a misunderstanding.  All of the things in the “services”
>> field of
>> your operating-system configuration are “system services”, so
>> all of
>> them get updated.
>
> Should we think about changing the name for "system services"? The
> confusion with Shepherd services seems really easy to make. The
> Wikipedia article for GuixSD makes the same mistake, but I haven't
> had the chance to fix it yet. Maybe we should call them "system
> extensions", or "mixins", or something like that?

I would very much like to find a new term for them, because usually the
second thing I say about system services is that the naming is
unfortunate and collides with what people think is a shepherd service.

I’m not fond of “mixins” (this reminds me of the “traits”-like concept
in Ruby classes), nor do I really like “system extensions”, but I do
think that avoiding the naming conflict would be worth a bike-shed
discussion :)

--
Ricardo

GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
https://elephly.net