[systemd-devel] Vendor default masked service

[Umut Tezduyar Lindskog]

On Thu, May 28, 2015 at 2:15 PM, Dimitri John Ledkov
<dimitri.j.ledkov at intel.com> wrote:
> On 28 May 2015 at 12:56, Umut Tezduyar Lindskog <umut at tezduyar.com> wrote:
>> On Thu, May 28, 2015 at 1:17 PM, Lennart Poettering
>> <lennart at poettering.net> wrote:
>>> On Wed, 27.05.15 13:05, Umut Tezduyar Lindskog (umut at tezduyar.com) wrote:
>>>
>>>> On Tue, May 26, 2015 at 4:14 PM, Lennart Poettering
>>>> <lennart at poettering.net> wrote:
>>>> > On Tue, 26.05.15 11:53, Umut Tezduyar Lindskog (umut at tezduyar.com) wrote:
>>>> >
>>>> >> Hi,
>>>> >>
>>>> >> I was wondering if we have a way to provide vendor default masked
>>>> >> service?
>>>> >
>>>> > Well, so far our thinking was that if the vendor wants to make a unit
>>>> > completely unavailable he should simply not ship it in the first
>>>> > place.
>>>> >
>>>> > What's the usecase for a vendor masking a unit, but installing it? Why
>>>> > not remove it in the first place entirely?
>>>>
>>>> If we ship a product without the service, we don't have a way of
>>>> installing it again once the product is deployed.
>>>>
>>>> Use case would be: We use one software for a video encoder blade with
>>>> multiple CPUs. Every CPU runs the same software. We have a special
>>>> service which should only run on the first CPU. A generator installs
>>>> the .wants link for the service on first CPU. Another service could
>>>> try to talk to the special service over dbus causing it to be dbus
>>>> activated (where special service is only allowed to be up on first
>>>> CPU). We could install the dbus activation files with generator but it
>>>> gets messy to offload this logic to a generator. Also, special service
>>>> can be activated by using systemd's dbus interface.
>>>
>>> My recommendation would be to ship the dbus service file always, but
>>> make it direct to SystemdService=dbus-com.axis.foobar.waldi.service,
>>> and then manage dbus-com.axis.foobar.waldi.service as a symlink alias
>>> to the real bus service. All you do in your generator now is create
>>> the symlink or not create it...
>>>
>>> Wouldn't that work?
>>
>> For dbus activation it would work but other services can still
>> activate the service through systemd.
>
> it will attempt to dbus activate non-existing service file.... since
> there wouldn't be a symlink with a name
> dbus-com.axis.foobar.waldi.service pointing to anything real, and thus
> effectively masked, no?!
Nope. They can call StartUnit (org.freedesktop.systemd1,
/org/freedesktop/systemd1) or "systemctl start".
Umut
>
> --
> Regards,
>
> Dimitri.
> Pura Vida!
>
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