Nagios Docker Stack Plugin works locally but not remote

I have a plugin to check the services running on docker.
I’ve gone through all of the suggestions from the dozens of posts I have seen here, but I’m still not able to get this to work.
The commands all run individually and the script runs as well, locally.
I added the nrpe user to the wheel and docker groups and set the wheel group in visudo to run anything without a password.

I modified /etc/passwd temporarily to allow the nrpe user to login with a shell. The script runs with or without sudo.

This part passes successfully:

/bin/docker > /dev/null 2>&1
if [ $? -eq 1 ]; then
   echo "UNKNOWN - Missing docker binary"
   exit 3
fi

This part fails. The command exists with a ‘1’ and I can’t get any output from the docker command. I’ve tried several things, including writing it to a file, but every time the file is blank.

/bin/docker stack ls | grep $STACK
if [ $? -eq 1 ]; then
  echo "UNKNOWN - $STACK does not exist.  $(/usr/bin/sudo /bin/docker stack ls) \n  $(whoami)"
exit 3
fi

This is the output I’m getting:

UNKNOWN - ValidService does not exist.   \n  nrpe. 

Any idea what permission I’m missing or is it something else?

Answer

Attribution
Source : Link , Question Author : D.Fitz , Answer Author : D.Fitz