The easy approach is just to use Sonoff native software and and eWeLink Smart Home skill on echo and you are away, instructions in link here. However this means having another dependency on external web service (eWelink) another account, and an extra app on your phone etc.

Webhook relay


1. Download cli client for pi (arm)
2. rename to relay
3. place in pi directory
4. chmod +wx relayn
5. ./relay --help
6. on wed bsite register and get token
7. ./relay login -k token-key-here -s token-secret-here
to set tunnel:
1.at cmd prompt: ./relay connect https://localhost:1880
you can then reach the server at http:/xxxx.webrelay.io...

The sd on one of my pi 3 was corrupted, was working before (24/7), I guess that must be too much rw for the sd. Good opportunity to reinstall from scratch the pi os, as so many changes since I last updated. Note the lastest version (V2.5, Nov18) , means you have to install node red manually (more later).

IFTTT webhooks


Create ifttt webhooks applet:
1. Choose service: webhooks
2.Choose trigger: Receive a web request
3.Enter event name: e.g button1
4.Create trigger (then that)
5.Choose Action service: e.g google sheets, add row to sheet
6.Create Action