Firmware update message is sent (if needed) when device joins channel.

[jlmcgehee21]

References: https://github.com/nerves-hub/nerves_hub/blob/master/docs/client-server.md

Next, the server compares the running version of the firmware to the target version for that device on NervesHub. If those versions are different, then the channel queues a firmware update message to be sent as soon as the channel finishes the join process.

Depends On: #78

[jlmcgehee21]

We will need to look up devices by the serial added to socket.assigns in order to check the target version. I'm guessing this should map somehow to :identifier, is there a method for this that is specified somewhere?

Still browsing the codebase to see what I can find as well.

[fhunleth]

If I understand correctly, I think that serial needs to be mapped directly to :identifier for the time being. This code was written before we wanted to deal with the issue of IDs being reused across tenants. The current plan is to assign UUIDs to devices in addition to manufacturing-assigned serial numbers. Code would work with UUIDs. Humans would see the serial numbers (for the most part). Both numbers would be embedded in the certs. Since we're hand generating certs at the moment, I think that it's ok to skip worrying about UUIDs until cert generation is available.

@mobileoverlord You agree? I know that you're getting close on cert generation, but it's still probably end next week-ish before you have something ready.

[jlmcgehee21]

☝️ gets us part of the way there, but I think this issue should stay open until we can send an actual firmware image.