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Re: Services and log management/monitoring
From: |
Ludovic Courtès |
Subject: |
Re: Services and log management/monitoring |
Date: |
Fri, 19 Apr 2019 14:09:34 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Hi,
rendaw <address@hidden> skribis:
> I think fundamentally what I'd most like to know is when should I use a
> Shepherd service vs a non-Shepherd service. Maybe it's as simple as: if
> you don't have any specific requirements always define a Shepherd service.
It’s hard to answer that question in the abstract. Do you have an
example in mind that we could work through?
> As a metaphor, maybe Shepherd services would be similar to the plain
> units in systemd.
Yes, I think so.
> Beyond what a service actually is though I have a few more questions:
>
> * Both
> https://www.gnu.org/software/guix/manual/en/html_node/Service-Composition.html
> and
> https://www.gnu.org/software/guix/manual/en/html_node/Shepherd-Services.html#Shepherd-Services
> appear to show a dependency graph.
The first page shows a service extension graph.
The second page shows a graph of dependencies among Shepherd services.
These are two different beasts.
> Are the dependency graphs Shepherd and non-Shepherd services
> entirely separate? Or maybe I'm completely misunderstanding
> "extension" in this context. Can an inet service depend on a non-inet
> service? Can an inet service depend on a d-bus service? * Is there a
> way to hook into service events - that is, run some code when a
> service starts or stops?
An inetd service cannot “depend” on a non-inetd service; a D-Bus service
cannot depend on a non-D-Bus service. Both D-Bus and inetd have their
own notion of what a service is, how to start it, etc., which is
separate from what the Shepherd does.
I reckon that calling everything a “service” does not help understand
all this…
HTH,
Ludo’.