[systemd-devel] Placing systemd unit files on a non-root partition

[magnus at minimum.se]

> On Mi, 08.11.17 11:31, magnus at minimum.se (magnus at minimum.se) wrote:
>
>> Hi!
>>
>> My team is building a embedded (Linux) platform which is to be
>> distributed
>> within our company as a binary distribution. On top of the platform,
>> other
>> teams write applications and put in branding to create products.
>>
>> To separate the applications from the platform, apps and related files
>> are
>> placed in a separate partition that gets mounted at boot by systemd.
>> When the system boots, the applications on the separate partition should
>> start, preferably by systemd.
>
> The question is what "mounted at boot" precisely means.
>
> sytemd is designed to calculate the initial transaction at boot, and
> then ideally it boots all the way through to it. If you make units
> available later, then the initial transaction isn't good enough, it
> needs to be redone. Which is something you can do, but it's not
> pretty, as you first need to tell systemd to reload its configuration,
> and then enqueue whatever else new want to enqueue.

Out of curiousity, how would one tell systemd to reload its configure and
enqueue new units? (disregarding its prettiness)

>
> A much better approach is to have everything ready at the moment as
> the host PID 1 is invoked, i.e. by placing everything on the root
> disk, or mount the auxiliary disks already in the initrd, i.e. before
> the system transitions to the host PID 1.
>
> Lennart
>
> --
> Lennart Poettering, Red Hat
>