#!/usr/bin/python3 -u # The -u option above turns off block buffering of python output. This # assures that each error message gets individually printed to the log file. # # Module: arednsigAgent.py # # Description: This module acts as an agent between the aredn node # and aredn mest services. The agent periodically sends an http # request to the aredn node, processes the response from # the node, and performs a number of operations: # - conversion of data items # - update a round robin (rrdtool) database with the node data # - periodically generate graphic charts for display in html documents # - write the processed node status to a JSON file for use by html # documents # # Copyright 2020 Jeff Owrey # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see http://www.gnu.org/license. # # Revision History # * v20 released 11 Jan 2020 by J L Owrey; first release # * v21 released 13 Feb 2020 by J L Owrey; fixed bug occuring when node # powers on and signal data memory is empty. Data points with N/A data # are discarded. # * v22 released 31 Mar 2020 by J L Owrey; upgraded for compatibility with # Aredn firmware version 3.20.3.0. This agent now downloads the node's # status page and parsed the signal data from the html. # * v23 released 11 Jun 2021 by J L Owrey; remove unused code. # * v24 released 14 Jun 2021 by J L Owrey; minor revisions # #2345678901234567890123456789012345678901234567890123456789012345678901234567890 import os import sys import signal import subprocess import multiprocessing import time import json from urllib.request import urlopen ### ENVIRONMENT ### _USER = os.environ['USER'] _SERVER_MODE = "primary" ### DEFAULT AREDN NODE URL ### # set url of the aredn node _DEFAULT_AREDN_NODE_URL = "{your AREDN mesh node url" ### FILE AND FOLDER LOCATIONS ### # folder for containing dynamic data objects _DOCROOT_PATH = "/home/%s/public_html/arednsig/" % _USER # folder for charts and output data file _CHARTS_DIRECTORY = _DOCROOT_PATH + "dynamic/" # location of data output file _OUTPUT_DATA_FILE = _DOCROOT_PATH + "dynamic/arednsigData.js" # database that stores node data _RRD_FILE = "/home/%s/database/arednsigData.rrd" % _USER ### GLOBAL CONSTANTS ### # max number of failed data requests allowed _MAX_FAILED_DATA_REQUESTS = 2 # AREDN node data request interval in seconds _DEFAULT_DATA_REQUEST_INTERVAL = 60 # number seconds to wait for a response to HTTP request _HTTP_REQUEST_TIMEOUT = 5 # chart update interval in seconds _CHART_UPDATE_INTERVAL = 600 # standard chart width in pixels _CHART_WIDTH = 600 # standard chart height in pixels _CHART_HEIGHT = 150 # Set this to True only if this server is intended to relay raw ### GLOBAL VARIABLES ### # turn on or off of verbose debugging information verboseMode = False debugMode = False # The following two items are used for detecting system faults # and aredn node online or offline status. # count of failed attempts to get data from aredn node failedUpdateCount = 0 # detected status of aredn node device nodeOnline = True # ip address of aredn node arednNodeUrl = _DEFAULT_AREDN_NODE_URL # frequency of data requests to aredn node dataRequestInterval = _DEFAULT_DATA_REQUEST_INTERVAL # chart update interval chartUpdateInterval = _CHART_UPDATE_INTERVAL ### PRIVATE METHODS ### def getTimeStamp(): """ Set the error message time stamp to the local system time. Parameters: none Returns: string containing the time stamp """ return time.strftime( "%m/%d/%Y %T", time.localtime() ) ##end def def getEpochSeconds(sTime): """Convert the time stamp supplied in the supplied string to seconds since 1/1/1970 00:00:00. Parameters: sTime - the time stamp to be converted must be formatted as %m/%d/%Y %H:%M:%S Returns: epoch seconds """ try: t_sTime = time.strptime(sTime, '%m/%d/%Y %H:%M:%S') except Exception as exError: print('%s getEpochSeconds: %s' % (getTimeStamp(), exError)) return None tSeconds = int(time.mktime(t_sTime)) return tSeconds ##end def def setStatusToOffline(): """Set the detected status of the aredn node to "offline" and inform downstream clients by removing input and output data files. Parameters: none Returns: nothing """ global nodeOnline # Inform downstream clients by removing output data file. if os.path.exists(_OUTPUT_DATA_FILE): os.remove(_OUTPUT_DATA_FILE) # If the aredn node was previously online, then send # a message that we are now offline. if nodeOnline: print('%s aredn node offline' % getTimeStamp()) nodeOnline = False ##end def def terminateAgentProcess(signal, frame): """Send a message to log when the agent process gets killed by the operating system. Inform downstream clients by removing input and output data files. Parameters: signal, frame - dummy parameters Returns: nothing """ # Inform downstream clients by removing output data file. if os.path.exists(_OUTPUT_DATA_FILE): os.remove(_OUTPUT_DATA_FILE) print('%s terminating arednsig agent process' % getTimeStamp()) sys.exit(0) ##end def ### PUBLIC METHODS ### def getNodeData(dData): """Send http request to aredn node. The response from the node contains the node signal data as unformatted ascii text. Parameters: none Returns: True if successful, or False if not successful """ try: currentTime = time.time() response = urlopen(arednNodeUrl, timeout=_HTTP_REQUEST_TIMEOUT) if verboseMode: requestTime = time.time() - currentTime print("http request: %.4f seconds" % requestTime) content = response.read().decode('utf-8') content = content.replace('\n', '') content = content.replace('\r', '') if content == "": raise Exception("empty response") except Exception as exError: # If no response is received from the device, then assume that # the device is down or unavailable over the network. In # that case return None to the calling function. print("%s getNodeData: %s" % (getTimeStamp(), exError)) return False ##end try if debugMode: print(content) dData['content'] = content return True ##end def def parseDataString(dData): """Parse the node signal data JSON string from the aredn node into its component parts. Parameters: sData - the string containing the data to be parsed dData - a dictionary object to contain the parsed data items Returns: True if successful, False otherwise """ sData = dData.pop('content') try: strBeginSearch = 'Signal/Noise/Ratio' \ '' strEndSearch = 'dB' iBeginIndex = sData.find(strBeginSearch) + len(strBeginSearch) iEndIndex = sData.find(strEndSearch, iBeginIndex) #print("search params: %d, %d" % (iBeginIndex, iEndIndex)) if iBeginIndex == -1 or iEndIndex == -1: raise Exception("signal data not found in status page") snr = sData[iBeginIndex:iEndIndex] snr = snr.replace(' ','') lsnr = snr.split('/') dData['time'] = getEpochSeconds(getTimeStamp()) dData['signal'] = lsnr[0] dData['noise'] = lsnr[1] dData['snr'] = lsnr[2] except Exception as exError: print("%s parse failed: %s" % (getTimeStamp(), exError)) return False return True ##end def def writeOutputFile(dData): """Write node data items to the output data file, formatted as a Javascript file. This file may then be accessed and used by by downstream clients, for instance, in HTML documents. Parameters: sData - a string object containing the data to be written to the output data file Returns: True if successful, False otherwise """ # Write file for use by html clients. The following two # data items are sent to the client file. # * The last database update date and time # * The data request interval lastUpdate = time.strftime( "%m.%d.%Y %T", time.localtime(dData['time']) ) # Format data into a JSON string. jsData = json.loads("{}") try: jsData.update({"date": lastUpdate}) jsData.update({"chartUpdateInterval": chartUpdateInterval}) jsData.update({"dataRequestInterval": dataRequestInterval}) jsData.update({"serverMode": _SERVER_MODE}) sData = "[%s]" % json.dumps(jsData) except Exception as exError: print("%s writeOutputFile: %s" % (getTimeStamp(), exError)) return False if debugMode: print(sData) try: fc = open(_OUTPUT_DATA_FILE, "w") fc.write(sData) fc.close() except Exception as exError: print("%s write output file failed: %s" % (getTimeStamp(), exError)) return False return True ## end def def updateDatabase(dData): """ Update the rrdtool database by executing an rrdtool system command. Format the command using the data extracted from the aredn node response. Parameters: dData - dictionary object containing data items to be written to the rr database file Returns: True if successful, False otherwise """ # Format the rrdtool update command. strFmt = "rrdtool update %s %s:%s:%s:%s:%s:%s:%s:%s" strCmd = strFmt % (_RRD_FILE, dData['time'], dData['signal'], \ dData['noise'], dData['snr'], '0', \ '0', '0', '0') if debugMode: print("%s" % strCmd) # DEBUG # Run the command as a subprocess. try: subprocess.check_output(strCmd, shell=True, \ stderr=subprocess.STDOUT) except subprocess.CalledProcessError as exError: print("%s: rrdtool update failed: %s" % \ (getTimeStamp(), exError.output)) return False if verboseMode and not debugMode: print("database updated") return True ##end def def setNodeStatus(updateSuccess): """Detect if aredn node is offline or not available on the network. After a set number of attempts to get data from the node set a flag that the node is offline. Parameters: updateSuccess - a boolean that is True if data request successful, False otherwise Returns: nothing """ global failedUpdateCount, nodeOnline if updateSuccess: failedUpdateCount = 0 # Set status and send a message to the log if the node was # previously offline and is now online. if not nodeOnline: print('%s aredn node online' % getTimeStamp()) nodeOnline = True else: # The last attempt failed, so update the failed attempts # count. failedUpdateCount += 1 if failedUpdateCount > _MAX_FAILED_DATA_REQUESTS: # Max number of failed data requests, so set # node status to offline. setStatusToOffline() ##end def def createGraph(fileName, dataItem, gLabel, gTitle, gStart, lower, upper, addTrend, autoScale): """Uses rrdtool to create a graph of specified node data item. Parameters: fileName - name of file containing the graph dataItem - data item to be graphed gLabel - string containing a graph label for the data item gTitle - string containing a title for the graph gStart - beginning time of the graphed data lower - lower bound for graph ordinate #NOT USED upper - upper bound for graph ordinate #NOT USED addTrend - 0, show only graph data 1, show only a trend line 2, show a trend line and the graph data autoScale - if True, then use vertical axis auto scaling (lower and upper parameters are ignored), otherwise use lower and upper parameters to set vertical axis scale Returns: True if successful, False otherwise """ gPath = _CHARTS_DIRECTORY + fileName + ".png" trendWindow = { 'end-1day': 7200, 'end-4weeks': 172800, 'end-12months': 604800 } # Format the rrdtool graph command. # Set chart start time, height, and width. strCmd = "rrdtool graph %s -a PNG -s %s -e now -w %s -h %s " \ % (gPath, gStart, _CHART_WIDTH, _CHART_HEIGHT) # Set the range and scaling of the chart y-axis. if lower < upper: strCmd += "-l %s -u %s -r " % (lower, upper) elif autoScale: strCmd += "-A " strCmd += "-Y " # Set the chart ordinate label and chart title. strCmd += "-v %s -t %s " % (gLabel, gTitle) # Show the data, or a moving average trend line over # the data, or both. strCmd += "DEF:dSeries=%s:%s:LAST " % (_RRD_FILE, dataItem) if addTrend == 0: strCmd += "LINE1:dSeries#0400ff " elif addTrend == 1: strCmd += "CDEF:smoothed=dSeries,%s,TREND LINE2:smoothed#006600 " \ % trendWindow[gStart] elif addTrend == 2: strCmd += "LINE1:dSeries#0400ff " strCmd += "CDEF:smoothed=dSeries,%s,TREND LINE2:smoothed#006600 " \ % trendWindow[gStart] if debugMode: print("%s" % strCmd) # DEBUG # Run the formatted rrdtool command as a subprocess. try: result = subprocess.check_output(strCmd, \ stderr=subprocess.STDOUT, \ shell=True) except subprocess.CalledProcessError as exError: print("rrdtool graph failed: %s" % (exError.output)) return False if verboseMode: print("rrdtool graph: %s\n" % result.decode('utf-8'), end='') return True ##end def def generateGraphs(): """Generate graphs for display in html documents. Parameters: none Returns: nothing """ autoScale = False # The following will force creation of charts # of only signal strength and S/N charts. Note that the following # data items appear constant and do not show variation with time: # noise level, rx mcs, rx rate, tx mcs, tx rate. Therefore, until # these parameters are demonstrated to vary in time, there is no point # in creating the charts for these data items. createAllCharts = False # 24 hour stock charts createGraph('24hr_signal', 'S', 'dBm', 'RSSI\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale) createGraph('24hr_snr', 'SNR', 'dB', 'SNR\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale) # 4 week stock charts createGraph('4wk_signal', 'S', 'dBm', 'RSSI\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale) createGraph('4wk_snr', 'SNR', 'dB', 'SNR\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale) # 12 month stock charts createGraph('12m_signal', 'S', 'dBm', 'RSSI\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale) createGraph('12m_snr', 'SNR', 'dB', 'SNR\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale) if verboseMode: #print() # print a blank line to improve readability when in debug mode pass ##end def def getCLarguments(): """Get command line arguments. There are four possible arguments -d turns on debug mode -v turns on verbose debug mode -t sets the aredn node query interval -u sets the url of the aredn nodeing device Returns: nothing """ global verboseMode, debugMode, dataRequestInterval, \ arednNodeUrl index = 1 while index < len(sys.argv): if sys.argv[index] == '-v': verboseMode = True elif sys.argv[index] == '-d': verboseMode = True debugMode = True elif sys.argv[index] == '-p': try: dataRequestInterval = abs(int(sys.argv[index + 1])) except: print("invalid polling period") exit(-1) index += 1 elif sys.argv[index] == '-u': arednNodeUrl = sys.argv[index + 1] if arednNodeUrl.find('http://') < 0: arednNodeUrl = 'http://' + arednNodeUrl index += 1 else: cmd_name = sys.argv[0].split('/') print("Usage: %s [-d] [-v] [-p seconds] [-u url]" % cmd_name[-1]) exit(-1) index += 1 ##end def def main(): """Handles timing of events and acts as executive routine managing all other functions. Parameters: none Returns: nothing """ global dataRequestInterval signal.signal(signal.SIGTERM, terminateAgentProcess) signal.signal(signal.SIGINT, terminateAgentProcess) print('%s starting up arednsig agent process' % \ (getTimeStamp())) # last time output JSON file updated lastDataRequestTime = -1 # last time charts generated lastChartUpdateTime = - 1 # last time the rrdtool database updated lastDatabaseUpdateTime = -1 ## Get command line arguments. getCLarguments() ## Exit with error if rrdtool database does not exist. if not os.path.exists(_RRD_FILE): print('rrdtool database does not exist\n' \ 'use createArednsigRrd script to ' \ 'create rrdtool database\n') exit(1) ## main loop while True: currentTime = time.time() # get current time in seconds # Every web update interval request data from the aredn # node and process the received data. if currentTime - lastDataRequestTime > dataRequestInterval: lastDataRequestTime = currentTime dData = {} # Get the data string from the device. result = getNodeData(dData) # If successful parse the data. if result: result = parseDataString(dData) # If parse successful, write data output data file. if result: writeOutputFile(dData) # If write output file successful, update the database. if result: result = updateDatabase(dData) # Set the node status to online or offline depending on the # success or failure of the above operations. setNodeStatus(result) # At the chart generation interval, generate charts. if currentTime - lastChartUpdateTime > chartUpdateInterval: lastChartUpdateTime = currentTime p = multiprocessing.Process(target=generateGraphs, args=()) p.start() # Relinquish processing back to the operating system until # the next update interval. elapsedTime = time.time() - currentTime if verboseMode: if result: print("update successful: %s sec" % elapsedTime) else: print("update failed: %s sec" % elapsedTime) remainingTime = dataRequestInterval - elapsedTime if remainingTime > 0.0: time.sleep(remainingTime) ## end while return ## end def if __name__ == '__main__': main()