Quick and dirty OpenWebRX Nagios Plugin

openwebrx-nagios.py

#!/usr/bin/env python3

import time
import websocket
import re
import requests
import math
import statistics
import threading
import sys
import argparse

from datetime import datetime

class OpenWebRXStats:
  re_message_smeter = re.compile(b"MSG s=([0-9\.\-\e]+)")
  re_message_setup = re.compile(b"MSG center_freq=([0-9]+) bandwidth=([0-9]+) fft_size=([0-9]+) fft_fps=([0-9]+).* setup")

  samples = []
  freq = 0
  ws = None

  def __init__(self, freq, host, timeout=10):
    self.freq = freq
    self.host = host
    self.timeout = timeout

  def start(self):
    id, offset = self.getId("http://%s/" % self.host)
    if (id is not None):
      websocket.enableTrace(False)
      self.ws = websocket.WebSocketApp("ws://%s/ws/%s" % (self.host, id),
                                    on_message = self.on_message,
                                    on_open = self.on_open,
                                    on_error = self.on_error)
      
      t = threading.Timer(self.timeout, self.endStats)
      t.start()

      self.ws.run_forever()

  def endStats(self):
    self.ws.close()

  def getId(self, url):
    headers = {'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36'}
    r = requests.get(url, timeout=5, headers=headers)
    if r.status_code == 200:
      re_client = re.compile("var client_id=\"([a-z0-9]+)\";")
      re_offset = re.compile("var starting_offset_frequency = ([0-9]+);")

      client_id = None
      offset_freq = None

      for line in r.text.split("\n"):
        m_client = re_client.search(line)
        m_offset = re_offset.search(line)
        if (m_client):
          client_id = m_client.group(1)
        elif (m_offset):
          offset_freq = m_offset.group(1)

        if (client_id and offset_freq):
          return client_id, int(offset_freq)

      return None, None

  def on_message(self, ws, message):
    match_smeter = self.re_message_smeter.match(message)
    match_setup = self.re_message_setup.match(message)
    
    if (match_setup):
      ws.send("SET low_cut=-4000 high_cut=4000 offset_freq=%s" % (self.freq - int(match_setup.group(1))))
    elif (match_smeter):
      self.samples.append(10 * math.log10(float(match_smeter.group(1))))

  def on_error(self, ws, error):
    print("error: %s" % error)

  def on_open(self, ws):
    ws.send("SERVER DE CLIENT openwebrx.js")
    ws.send("SET output_rate=11025 action=start")  


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-s', '--server', default="127.0.0.1:8073")
    parser.add_argument('-f', '--freq', default="1638000", type=int)
    parser.add_argument('-t', '--timeout', default="5", type=int)
    parser.add_argument('-w', '--warning', default="-30", type=int)
    parser.add_argument('-c', '--critical', default="-45", type=int)
    args = parser.parse_args()

owrx = OpenWebRXStats(args.freq, args.server, args.timeout)
owrx.start()

if (len(owrx.samples) == 0):
  print("No samples received")
  sys.exit(1)
else:
  mean = statistics.mean(owrx.samples)
  if (mean < args.critical):
    print("Carrier Critical: %d KHz average over %d samples %.2f dB" % (owrx.freq / 1000, len(owrx.samples), mean))
    exit(2)
  if (mean < args.warning):
    print("Carrier Low: %d KHz average over %d samples %.2f dB" % (owrx.freq / 1000, len(owrx.samples), mean))
    exit(1)
  else:
    print("OK: %d KHz average over %d samples %.2f dB" % (owrx.freq / 1000, len(owrx.samples), mean))
    exit(0)