Deploying fleets of micropython devices but with subtlety different configurations

[proffalken]

Hey all,

I'm building a solution using esp32 devices and micropython that utilises LoRaWAN.

As part of it, each device needs to be given a distinct name and LoRaWAN configuration (DevEUI, AppSKey etc).

What's the best way to do this in micropython?

I'm currently flashing the code using Ampy, but I'm wondering if there's a better solution than manually updating the config.py file, copying the code over, and restarting the device?

[peterhinch]

Unless you can derive things from machine.unique_id() or the MAC address I think you're stuck with a config.py. There is also non-volatile storage but I'm not sure how you'd use it in this application...

[proffalken]

ok, thanks, I'll take a look

[cwalther]

Maybe have the device itself connect to a server on the first boot to retrieve its personal config.py (identified by sending along the MAC address or unique ID with the request)? You could put that code in the initial config.py that is then replaced by the real one.

[proffalken]

Thanks, but in this case that's not possible.

The reason I'm using LoRaWAN and not WiFi is because I can't get a WiFi signal to travel 5 miles, but I can do that with LoRaWAN!

It's looking like it's a manual change to the config for each device at the moment.

If I were writing this in C++ with platformio.org then I'd be exporting the variables into the environment for each individual board (easy to do based on a "for" loop) - I guess I could rewrite parts of the config file based on the environment using Jinja2 or similar, but that feels reasonably heavy for this...

[cwalther]

I meant while it’s on your desk, before it’s deployed 5 miles into the wild.

[proffalken]

I meant while it’s on your desk, before it’s deployed 5 miles into the wild.

Ah, yes, a very good idea!

So basically a requests.get() in boot.py to pull down the config.py file if it doesn't already exist.

That would work...

Thanks!

[cwalther]

If you put it in config.py instead of boot.py, it’s out of the way (replaced by the real config.py) when the device is deployed and doesn’t take up any space and can’t cause any bugs anymore in the field.

[proffalken]

Awesome.

Even better, I've just realised that I can probably reuse some of the code (or at least the logic behind it) from something I wrote about 10 years ago to provision physical servers via Puppet and TFTP!

Thanks for the advice!

[jimmo]

I'm currently flashing the code using Ampy,

@proffalken Not your actual question, but have you seen mpremote ? It's a lot more sophisticated than ampy and has a few really useful features for development (e.g. mount ). https://docs.micropython.org/en/latest/reference/mpremote.html

[proffalken]

@jimmo it's definitely part of the original question - ampy is... fine... but I'm sure there are better ways of doing this.

I'll checkout mpremote later on today, thanks!