[systemd-devel] when mount is delayed - start unit which depends on it - ?

[Colin Guthrie]

Mantas Mikulėnas wrote on 18/09/2021 09:41:
> 
> On Fri, Sep 17, 2021 at 2:40 PM lejeczek <peljasz at yahoo.co.uk 
> <mailto:peljasz at yahoo.co.uk>> wrote:
> 
>     Hi guys.
> 
>     I'm trying to have unit to start...
>     well,
>     I have a luks device which waits for manual passphrase
>     input, when that happens 'systemd' mounts, without user
>     intervention(which is great), that luks device.
>     fstab:
>     /dev/mapper/luks.devs /devs   ext4
>     noatime,nobarrier,noatime,x-systemd.device-timeout=2,nofail 1 2
>     and now I'll have many units/services which depend on that
>     mount, because they need to get to paths to get their
>     configs & other bits.
> 
>     Question - how do I make such a unit to re/start when
>     'systemd' does the mount? Naturally, ideally without any
>     ways external to 'systemd'.
> 
> 
> If units need this mount, then *actually* make them depend on this mount 
> – as in, "Requires=devs.mount" and "After=devs.mount" in each service's 
> [Unit].

I agree this is correct, but I don't think it does what the user wants. 
i.e. when the mount eventually happens (e.g. after all the jobs have 
timed out and the user manually mounts it), the rest of the transaction 
continues where it left off rather than just sitting their failed/unstarted.

I think there is possibly something you could do with a udev rule, a 
custom target unit and PartOf= in the dependant services?

Or perhaps a path unit based on a file inside the mounted filesystem 
which again triggers a target (again coupled with PartOf in the 
dependant services).


HTHs


-- 

Colin Guthrie
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http://colin.guthr.ie/

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