[systemd-devel] Help: Questions regarding systemd service order

[Mantas Mikulėnas]

On Tue, Nov 12, 2024 at 12:13 PM Tony Rodriguez <unixpro1970 at gmail.com>
wrote:

> Hoping I can accomplish the following via a simple UNIT modification or
> service script?
>
>
> Questions:
>
> A)  How can my service always runs "last" within local-fs-pre.target?
>
> For Example:
>
> Need my service to always run last within the local-fs-pre.target, even
> if others add another services later within local-fs-pre.target. Still
> want my service to always run last within this local-fs-pre.target.
>
> Note: I will not know services others may later add within the
> local-fs-pre.target
>

Systemd deliberately doesn't have a definite concept of "last" or "first".
(More importantly, what happens if another service also wants to be "last"?)

It's specifically the purpose of targets themselves to be used as barriers.
Instead of "After=*.mount" you would have "After=local-fs.target" because
all those mounts are in local-fs.target.


>
>
> B) How can I make my service run after all .mount(s) within
> local-fs-pre.target, before local-fs.target, especially if I don't know
> all the .mount(s)?  The .mount files are located within
> /var/run/systemd/generator/*
>
> ls -l /var/run/systemd/generator/*.mount
> -rw-r--r-- 1 root root 390 Nov 12 00:59
> /var/run/systemd/generator/boot-efi.mount
> -rw-r--r-- 1 root root 449 Nov 12 00:59
> /var/run/systemd/generator/boot.mount
> -rw-r--r-- 1 root root 428 Nov 12 00:59
> /var/run/systemd/generator/home.mount
> -rw-r--r-- 1 root root 239 Nov 12 00:59 /var/run/systemd/generator/-.mount
> -rw-r--r-- 1 root root 424 Nov 12 00:59
> /var/run/systemd/generator/tmp.mount
> -rw-r--r-- 1 root root 241 Nov 12 00:59
> /var/run/systemd/generator/usr.mount
> -rw-r--r-- 1 root root 424 Nov 12 00:59
> /var/run/systemd/generator/var.mount
>
> -rw-r--r-- 1 root root 424 Nov 12 00:59
> /var/run/systemd/generator/test.mount
>
>
> Appears the UNIT section doesn't support a wildcard for .mount(s)
>
> This doesn't work
>
> #After=local-fs-pre.target *.mount
>
> The following works, but have to hard code mounts. Would like to
> dynamically populate mounts for "After=" within my service file.
>
> After=local-fs-pre.target boot.mount boot-efi.mount -.mount usr.mount
> var.mount tmp.mount home.mount
> Before=local-fs.target
>
> [Unit]
> Description=mytest.service
> DefaultDependencies=no
> Wants=local-fs-pre.target
> After=local-fs-pre.target boot.mount boot-efi.mount -.mount usr.mount
> var.mount tmp.mount home.mount test.mount
> Before=local-fs.target
>
>
How come your home.mount is in local-fs-pre? That is exactly the kind of
mount that would be in local-fs. In fact, why do you have *any* mounts in
local-fs-pre?

-- 
Mantas Mikulėnas
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