systemd: use "After" with "Requisite"
The "Requisite" directive is intended to require that the virtio port device exists before starting the vdagent socket unit. If the device does not exist, the socket should fail to start. However, without using "After", the socket will still start even when the device is not present. The man page for systemd.unit (v239+) says the following about 'Requisite=': "Similar to Requires=. However, if the units listed here are not started already, they will not be started and the starting of this unit will fail immediately. Requisite= does not imply an ordering dependency, even if both units are started in the same transaction. Hence this setting should usually be combined with After=, to ensure this unit is not started before the other unit." See also https://github.com/systemd/systemd/issues/4756 for further details (particularly the following comment: https://github.com/systemd/systemd/issues/4756#issuecomment-267005324) Signed-off-by: Jonathon Jongsma <firstname.lastname@example.org> Acked-by: Lukáš Hrázký <email@example.com>