Ethernet and WiFi configuration for failover

[ss89]

Component name

ethernet

Link to component documentation on our website

https://esphome.io/components/ethernet.html

Describe the enhancement

I would like the ethernet and wifi component to be able to co-exist and/or to be able to fail-over to the other.

Use cases

My use-case is a small observability project that may notify me via a network connection - which might also be down, so the firmware would need to failover to the other network (switching going from rj45 to wifi or vice versa).
Bonus point: I would like to be able to detect which network is currently active and i would like to be able to specifically have only one of two active at the same time.

Anything else?

In the simples possible configuration, I would imagine to configure such fallback like:

wifi:
  id: wifi
  failover_to: ethernet

ethernet:
  id: ethernet
  failover_to: wifi

In a more clean configuration, I would imagine to configure the whole networking more like:

wifi:
  failover_to: wired_main
  networks:
    - id: wifi_main
      ssid: foo
      password: bar
ethernet:
  failover_to: wifi_main
  networks:
    - id: wired_main
      vlan: 0
      ...

[github-actions[bot]]

🏷️ I've automatically added the component: ethernet label to help categorize this feature request.

[ss89]

this should also get the component wifi assigned

[jesserockz]

If someone wants to implement this, I would actually put the failover config in the top level network configuration.

network:
  priority:
    - ethernet
    - wifi

wifi:
  ...

ethernet:
  ...