That way that this is performed is by first adding a depends_on entry
for the target service if it appears in a network mode. Then when we
generate the docker container for this service, we use the containerId
of the target container and replace the network_mode with
`container:<id>`.
When comparing state, we check that the containerId still points to the
contianerId of the target container, and in this way we ensure that
when a network mode target container changes, we change the dependent
container too.
Change-type: minor
Closes: #851
Signed-off-by: Cameron Diver <cameron@balena.io>