It is possible there are many things like this to fix. I made too much
complexity on searching services in deployment while the map key is
enough to get the righ deployment for a compose service.
Need to check the "same-pod" possibilities later.
If "depends_on" is set, we need to ensure that the target service has
got declared ports. It's necessary, at this time, to ensure the target
is started (with an initContainer)
As soon as Kubernetes proposes a better check, we will be able to fix
this requirement.