Answering here some points from you other thread Missing Data & Logs - #4 by m31d4ri0n
I cannot really disagree with your ambition as I too run all my sites as RO installs and they all report back to a common emoncms server. Although I do have to say the likelyhood of an SD card failure with the emonSD image is quite unlikely, there have been no reports of such for quite a while, the SDcard tech has improved and the emonSD is prodominantly RO and emoncms is “low-write” but it isn’t impossible.
IMO the best OEM images were the “OEM rock solid gateway” images, they were totally RO and only had a stripped down OS plus the OEM gateway software, which was emonHub’s predecessor. This was a forwarding only solution but as the name suggested it was rock solid.
The emonSD image is quite a lot of software to unravel and the way it is specifically set up is for a local emoncms, if you what to go this route I would recommend starting with a bare OS image, make it RO, add emonhub (original not the emonPi variant) and to that you could add a bespoke utility to interface with the LCD and button on the emonPi. That is all you NEED but you can add to it as you wish.
The build guide for the emonSD is here
https://github.com/openenergymonitor/emonpi/blob/master/docs/SD-card-build.md
and the changlog here
as you can see there’s a lot to unravel. If all you are concerned about is the SDcard then you could as suggested in my first post, just have a remote emoncms and not use emoncms on the emonPi, that is the simplest route and I guess it is the “officially supported” route, but I would be more than happy to help develop a “rock-solid” type forwarding-only (read-only) alternative if built from scratch rather than stripping away from the existing image. personally I would also want to steer clear of splitting the emoncms install across servers as you suggest in this thread, mainly as it would force a one device to one (split) emoncms instance and it’s unlikely to be robust enough for my needs.