display clock offset from ntp using chrony

clock-offset-from-ntp.py

#!/usr/bin/env python

import sys
import shlex
import subprocess

def run_cmd():
    """chronyc tracking
Reference ID    : 50484330 (PHC0)
Stratum         : 1
Ref time (UTC)  : Wed Mar 06 12:17:24 2024
System time     : 0.000000137 seconds fast of NTP time
Last offset     : -0.000000099 seconds
RMS offset      : 0.000004309 seconds
Frequency       : 1.295 ppm fast
Residual freq   : +0.000 ppm
Skew            : 0.137 ppm
Root delay      : 0.000000001 seconds
Root dispersion : 0.000023911 seconds
Update interval : 8.0 seconds
Leap status     : Normal


-c makes the output more processable like:

chronyc -c tracking
50484330,PHC0,1,1709727533.139866748,0.000004315,-0.000003372,0.000002759,1.274,-0.005,0.161,0.000000001,0.000029493,8.0,Normal
0        1    2 3                    4


"""
    c = "chronyc -c tracking"
    cmd = shlex.split(c)
    output, error = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()
    return (output, error)

def main():
    """
    Use **chronyc tracking command** on linux show clock offset from it's ntp source.

    """
    #maximum_divergence_tolerated = float(0.1)
    #maximum_divergence_tolerated = float(0.000001)
    maximum_divergence_tolerated = float(0.00001)
    clock_state = run_cmd()
    clock_data = clock_state[0].decode().split(',')
    #clock_data = clock_state[0].split(',')
    clock_offset_from_ntp = float(clock_data[4])

    if abs(clock_offset_from_ntp) >= maximum_divergence_tolerated:
       print('oh no, clock is off by {co:06.12f} max_divergence_tolerated is {mt:06.12f}'.format(co=clock_offset_from_ntp, mt=maximum_divergence_tolerated))
    else:
       print('good clock is {co:06.12f} which is within the tolerance of {mt:06.12f}'.format(co=clock_offset_from_ntp, cd=clock_data[4], mt=maximum_divergence_tolerated))


if __name__ == "__main__":
    main()