Permission problem Sense Hat node

Which node are you reporting an issue on?

node-red-node-pi-sense-hat

What are the steps to reproduce?

• Install node-red-node-pi-sense-hat
• Use the Sense Hat node (out) in a flow
• Connect the node to inject with [4-6,*,purple]
• Deploy the flow

What happens?

• The Sense Hat node is [disconnected]
• Log shows:
  pam_unix(sudo:auth): conversation failed
pam_unix(sudo:auth): auth could not identify password for [nodered]
• The Sense Hat LED array is blank

Seems like the node is trying to sudo a certain command and cannot without the user passwd. Since I can't find what the node is trying to access using sudo I can't specify that very command in /etc/sudoers as a NOPASSWD. The current workaround basically gives all access to all and any command to the dedicated user I created named nodered.

What do you expect to happen?

• The Sense Hat node is [connected]
• The Sense Hat LED array shows 3 vertical purple lines

Please tell us about your environment:

• Node-RED version: 3.0
• node.js version: 18
• npm version: 9.5
• Platform/OS: Raspberry Pi OS 64 bit latest
• Browser: Chrome

(Sub-optimal) first workaround

I put this line in /etc/sudoers: nodered ALL=(ALL) NOPASSWD: ALL

Better (current) workaround (March 12)

sudo is not needed when calling the sensehat Python script.

sensehat Python script (Line 18)

Replaced by (no $SUDO):

$python_cmd -u $BASEDIR/sensehat.py $@

My Python installation is pretty much run-of-the-mill (as the configuration of the SenseHat module) and does not require sudo when running the script linked above.

Thanks for your help.

Start with hardware/sensehat/sensehat, especially the linked line 18, and trace how the Sense Hat node launches sensehat.py. Reproduce the node-red-node-pi-sense-hat flow on Raspberry Pi OS and check the sudo authentication logs. Done means the node connects and displays the expected three vertical purple lines without requiring broad sudoers access.