[Snap] Implement Network Settings

[benfrancis]

As a user I want to be able to configure my network settings when using the snap package so that I can connect my gateway to a network.

Currently clicking on Network Settings in the web interface when using the snap package on Ubuntu displays a message which says "Network settings are not supported for this platform." This is because network settings are not implemented for Ubuntu, or Ubuntu Core.

This will require implementing network settings using NetworkManager in linux-ubuntu.ts and/or creating a linux-ubuntu-core.ts in /src/platforms.

See https://github.com/krellian/kiosk/blob/master/services/models/network.js for inspiration.

This will likely also require the snap to be permitted to use an additional interface.

[benfrancis]

@ogra1 The way I have been planning to implement this is to request the network-manager interface and configure networking by communicating with NetworkManager over D-Bus from Node.js. I previously did something similar for Krellian Kiosk, but it's quite low level and fiddly to implement and I found the documentation of the NetworkManager D-Bus API quite difficult to understand.

I note that there appear to be multiple interfaces for modifying network settings so before I make a start on this, is there a simpler approach I should be considering?

The WebThings Gateway user manual should give you an idea of the kinds of settings which need to be modified from Node.js.

There are other settings that will need implementing later including configuring mDNS, and a Wi-Fi hotspot during first time setup.

[benfrancis]

Potential approaches to implementing networking on Ubuntu Core:

• network-setup-control interface
  • "allows read/write access to Netplan configuration files" - probably not enough for what we need. We need to be able to list network interfaces and scan for Wi-Fi networks etc.
• network-control interface
  • "enables the configuration of networking and network namespaces via ip netns, providing a wide, privileged access to networking" - I don't know a lot about this
• network-manager interface
  • "enables access to NetworkManager, providing privileged access to configure and observe networking." - Does this just mean via DBus, or also the nmcli command line interface?
  • dbus npm module to provide raw access to dbus, I've used this before but it's tricky to use and the npm module hasn't been updated for 5 years
    • E.g. https://github.com/krellian/kiosk/blob/master/services/models/network.js
  • network-manager npm module to control NetworkManager
    • Appears to call nmcli on the back end https://github.com/MahdadGhasemian/node-network-manager/blob/main/index.js

[benfrancis]

• network-manager interface "enables access to NetworkManager, providing privileged access to configure and observe networking." - Does this just mean via DBus, or also the nmcli command line interface?
  • dbus npm module to provide raw access to dbus

FYI I've made a start using this approach in #3168 so we'll see how it goes.