This module will take care of applying the target state for the device and reporting its current state.
The state itself is handled by two other modules, ApplicationManager and DeviceConfig. The former will take care of running applications (including the dependent ones
via its Proxyvisor), and the latter will take care of device configuration like config.txt and supervisor configuration variables.
The way state is applied differs radically from the previous approach: the old application.coffee had a big `update` function that took all of the steps from fetching the target state
to running the containers. DeviceState, instead, does an iterative process through `triggerApplyTarget` of inferring the next steps to perform towards the target state, by looking at the current state and asking the ApplicationManager and DeviceConfig for
the next steps. It then applies the next steps and every time a step is completed, it schedules another round of inferring and applying the next steps.
Special care is taken to ensure `applyTarget` is not called simultaneously more than once.
This commit also adds a "device" module to handle reboot and shutdown, and moves gosuper calls to a separate module.
The module also uses a "network" module to manage network-related parts of the device's current state: IP addresses and the connectivity check.
The module implements a "normaliseLegacy" function that allows a migration from the models from older versions of the supervisor to the multicontainer models,
so that in case of a supervisor update we can have minimal downtime and bandwidth consumption when updating to the multicontainer supervisor - this migration allows
us to avoid cleaning up images, and also allows migrating the contents of the old /data for the app.
Changelog-Entry: Infer the current state of the device when applying the target state
Change-Type: patch
Signed-off-by: Pablo Carranza Velez <pablo@resin.io>
