Reliable stack deployment

In some cases the renderer and registrar run into a race condition when one is creating the shared instance. Sometimes, service that does not set up the instance starts with a half configured settings.py leading to strange bugs.

Using a service dependency does not work, as e.g the renderer will not always be present.

Ideas for a solution:

• using a per-container instance:
  • pros:
    • reliable instance creation/configuration
    • database as synchronization out of the box
  • cons:
    • duplication of files (especially static seems to be > 4GB; but actually unnecessary)
    • spinup times increased (how much?)
• sticking to shared instance, with better synchronization