[systemd-devel] systemd-218 - Requisite implies TriggeredByRestartOf

[Lennart Poettering]

On Thu, 14.05.15 21:23, Evert (evert.gentoo at planet.nl) wrote:

> Hi,
> 
> According to the systemd documentation, Requisite disallows starting a
> unit unless the specified unit has been started. This seems to work
> fine, however, if the specified unit has been restarted, this unit will
> be started too!
> This is not what should happen and it doesn't happen with a stop and
> start of the specified unit, so clearly, restart behaves different than
> stop followed by start.

Hmm, I figure this is a bug in systemd.

Whenever you have a unit A declare a Requisite= on a unit B then this
will actually create two dependencies: the actual Requisite= one plus
one in the opposite direction, of type RequiredBy=. Dependencies of
type "RequiredBy=" are mostly internal to systemd, you cannot
configure them directly (though you can query them using "systemctl
show"). They are used to track down what to stop when we get
"systemctl stop" by the user. Now, as a special shortcut we currently map
"Requisite=" and "Required=" to a reverse dependency of
"RequiredBy=", which is problematichere, since we'll hence make no
distinction between the two when processing "systemctl stop".

I figure we need to split up the reverse dep here, and introduce a
seperate RequisiteBy= dependency so that we can avoid this problem...

Lennart

-- 
Lennart Poettering, Red Hat