Local setup (skaffold): Incorrect DNS assumptions

[AurelienGasser]

The default "local" installation of the susbtra stack (skaffold run) assume that custom /etc/hosts entries present on the host are used during DNS resolution from inside running pods.

That appears to be the case in some setups:

• Docker-for-mac
• minikube with virtualbox driver

However, it appears not to be the case in other setups:

• some AWS setups (Worker pod cannot resolve substra-backend.node-1.com substra#150)
• minikube with docker driver (docker: /etc/hosts entries from host machine are ignored kubernetes/minikube#7802)

So, effectively, the default local installation of the substra stack only works in some environments.