How snapcraft nodejs plugin handle the Node.js environment when you create an app snap for different OS? - plugins

Question

I'm try to understand how the nodejs plugin i'm using to create snap node.js app handle the Node.js environment ? Example in this application :
parts:
webserver:
source: .
plugin: nodejs
nodejs-version: "12.13.1"
nodejs-package-manager: "yarn"
nodejs-yarn-version: "v1.21.1"
I'm defining to use Node.js v12.13.1 and Yarn v1.21.1 lunching the snapcraft commands:
snapcraft clean
snapcraft --debug
snap install my-snap-file.snap --dangerous
Now i'm able to run the command/service on my machine (amd64 Ubuntu 16.04 LTS) with Node.js v12.2.0 installed but i cant find the node.js env not in multipass instance not in another machine with installed Ubuntu Core 18, i mean i can't run command as node --version and so on and even the snap app doesn't work neither command neither service.
Other problem i've discovered digging in the Ubuntu Core 18 env installed on RaspBerry Pi3 is : When i've installed my snap with nodejs app in the folder /snap//bin i cannot run the ./node exec ! i get the error :
./node: 1: ./node: Syntax error: "(" unexpected
My questions are :
Why i get the ./node error ?
my-snap-file.snap bundle the Node.js v12.3.1 inside the mysnap ?
how i can test the node.js is working with the right version in multipass and other machine where i've installed only the snap bundling node.js ?
THks

Answer 1

Thanks to forum.snapcraft.io i've solved the issue ... i'm posting here to help people to solve these kind of issues too. This error is due to the snap that is NOT build on the actual target architecture you want to run it on. Make sure you build eg. armhf (raspberry pi3) actually on an armhf architecture device.
architectures:
- build-on: amd64
run-on: [amd64, armhf]
here you tell snapcraft that building on amd64 produces binary snaps that can run on amd64 and armhf … which is indeed not true (since building on amd64 will pull in only amd64 binaries). i’d drop that statement completely and make sure to build the armhf version on an armhf device (or on build.snapcraft.io). (Credits Ogra)
Read the Link about architectures in snapcraft.yaml
https://forum.snapcraft.io/t/architectures/4972