Support Surface Pro onboard buttons in Debian 9

config.ini

; Example configuration file for inputexec

[DEFAULT]
; ---traceback : Include full stack trace on exception
#traceback =

## Source
[source]
; --source-file : The source to read from (e.g /dev/input/event0)
file = /dev/input/by-id/usb-MICROSOFT_SAM_0.1.0000-if01-event-mouse
; --source-mode : Get shared/exclusive hold of the input device (evdev only)
; Options: exclusive, shared
mode = shared

## Formatting
[format]
; --format-pattern : Formatting pattern
pattern = {kind}.{symbol}
; --format-endline : End of line substring
endline = \n

## Action
[action]
; --action-mode : Action to perform on events
; Options: print, run_async, run_sync
mode = run_async
; --action-jobs : Number of jobs to run
jobs = 3
; --action-commands : Read input/command mappings from the ACTION_COMMANDS file, section [commands]
commands = surface-pro.ini

## Filtering events
[filter]
; --filter-kinds : Comma-separated list of event kinds to keep
kinds = keypress,keyhold

## Logging
[logging]
; --logging-target : Logging target
; Options: file, null, stderr, syslog
target = stderr
; --logging-file : For 'file' target, write logs to FILE
file = 
; --logging-level : Logging level
; Options: debug, error, info, warning
level = warning

install steps

sudo apt install pip
pip install inputexec
#copy surface-vol.py to /usr/local/bin
#copy surface-pro.ini to ~/
#copy config.ini to ~/
#copy surface-vol.desktop to ~/.config/autostart/
inputexec --config config.ini
#add it to startup
echo '%sudo ALL=NOPASSWD: /usr/local/bin/surface-vol.py' >> /etc/sudoers

surface-pro.ini

[commands]
keypress.KEY_LEFTMETA = sudo surface-vol.py KEY_LEFTMETA
keypress.KEY_VOLUMEDOWN = sudo surface-vol.py KEY_VOLUMEDOWN
keypress.KEY_VOLUMEUP = sudo surface-vol.py KEY_VOLUMEUP
keyhold.KEY_VOLUMEDOWN = sudo surface-vol.py KEY_VOLUMEDOWN
keyhold.KEY_VOLUMEUP = sudo surface-vol.py KEY_VOLUMEUP

surface-vol.desktop

[Desktop Entry]
Name=surface-vol
GenericName=A descriptive name
Comment=Some description about your script
Exec=/usr/local/bin/inputexec --config ~/inputexec.ini
Terminal=false
Type=Application
X-GNOME-Autostart-enabled=true

surface-vol.py

#!/usr/bin/env python
import sys
from time import sleep
from evdev import UInput, ecodes as e
ui = UInput()
key = e.ecodes[sys.argv[1]]

# accepts only KEY_* events by default
ui.write(e.EV_KEY, key, 1)  # KEY down
sleep(0.05)
ui.write(e.EV_KEY, key, 0)  # KEY up
ui.syn()

ui.close()