Sysemd in the nfsroot

[Justin Cattle]

Hi Thomas,


Did you ever have any time to take a look at this, or have any thoughts
about it ?


Cheers,
Just


On Tue, 10 May 2022 at 20:45, Justin Cattle <j at ocado.com> wrote:

> Hi Thomas,
>
>
> I found a bit of time to take a look.
>
> I have forked and created a branch with a demo of how it could work.  It's
> not meant to be the finished article, but hopefully it shows how some of it
> could be achieved.
>
> Things to note:
>
>    - Relevant part of NFSROOT config needs to be something like this:
>       - systemd systemd-sysv libpam-systemd sysvinit-core-
>    - Because of potential race conditions with starting usual tty
>    services, I select unused tty for this
>       - fai on tty11
>       - fai-maint on tty12
>    - fai-maint is a systemd service which creates a tty with a root bash
>    session already logged in.  It's just an example of how that kind of thing
>    could be achieved with systemd.
>    - Although I tried to make FAI itself still support both SysV and
>    Systemd, it's hard to do that in the packaging I think, so for this I
>    dropped SysV support in the packaging.
>       - You can use the systemd-sysv compatibility layer to create
>       service units, but that doesn't give as much control over the units [ they
>       are much more basic ], so native systemd is better.
>
>
> Please also note I haven't tested this exhaustively, so far I've only used
> it with a squashfs image, not an nfs root.
>
> I'd be happy to work with you to create a PR and review it together to try
> and integrate it, but I appreciate you may not want to look at this yet.
> It seems to be that multi init system packaging could be the trickiest
> part, and you may not want to drop SysV support any time soon.
>
> Please take a look and let me know what you think:
> https://github.com/ocadotechnology/fai/tree/systemd-support
>
>
> Cheers,
> Just
>
>
> On Fri, 6 May 2022 at 20:40, Thomas Lange <lange at cs.uni-koeln.de> wrote:
>
>> Hi Justin,
>>
>> I didn't had time to work on this yet. I do not know how to call the
>> main fai script from systemd, so its output is shown on the console
>> and the input is also read from the console. It must also work that
>> the admin can interrupt the fai run via ctrl-C and get an interactive
>> shell.
>> Does anyone know how to do this?
>>
>> Currently (using sysv init) the script is started as /etc/init.d/rcS
>> and starts some other daemons on demand (for e.g. sshd is only started
>> if FAI_FLAGS includes sshd). How do we do this using systemd?
>>
>>
>> >>>>> On Fri, 6 May 2022 15:02:30 +0100, Justin Cattle <j at ocado.com>
>> said:
>>
>>     > Hi,
>>     > I'm just wondering what the current blockers to using systemd in
>> the nfsroot are.  Are there some things that simply won't work, or is it
>> more about reducing complexity by only supporting
>>     > a single init system, or something else ?
>>
>>
>> --
>> best regards Thomas
>>
>

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