Currently there is no way for a service to become aware that
dhcp-all-interfaces is finished configuring all the interfaces at
boot time. This causes problems for applications like the
ironic-python-agent which scans the interfaces when it first starts as
part of the inspection stage and can race against dhcp-all-interfaces
bringing up the interfaces, leading to inconsistent results.
This patch ensures that the dhcp-all-interfaces script runs before any
network interface is configured and brought up by the rest of the
system, and also ensures that the ironic-agent element also waits for
the network to be online before starting. This is done by using the
network targets provided by systemd.
Change-Id: Id9583b7f54361aa603a6229da598ad6a0f0f7938
eb99fe7144