In our system, each site deployment contains multiple gateways managed with Balena. Each gateway (Raspberry Pi 3) provides an RS485 link to multiple child nodes (Raspberry Pi Zeros).
The child nodes do not have Internet connectivity or an IP link to the gateways, they are only connected through an industrial RS485 protocol. Over this protocol, we are able to transfer files or send commands to be executed - though these are received by our application running inside docker, rather than by ResinOS.
Balena has been very useful to develop the software on the child nodes. However, without IP connectivity we now have no way to manage application upgrades or configuration changes.
Is there a mechanism to manage our child nodes using Balena, perhaps by passing a container image over our RS485 link?
We found this document which speaks about a similar setup, but is quite old and does not mention ARM based systems: https://github.com/balena-io/balena-supervisor/blob/master/docs/dependent-apps.md