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-#!/usr/bin/python -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.

-#

-#2345678901234567890123456789012345678901234567890123456789012345678901234567890

-

-import os

-import urllib2

-import sys

-import signal

-import subprocess

-import multiprocessing

-import time

-import json

-

-_USER = os.environ['USER']

-_HOSTNAME = os.uname()[1]

-

-   ### DEFAULT AREDN NODE URL ###

-

-# set url of the aredn node

-

-_DEFAULT_AREDN_NODE_URL = "http://localnode:8080/cgi-bin/signal.json"

-

-    ### 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/arednsigOutputData.js"

-# dummy output data file

-_DUMMY_OUTPUT_FILE = _DOCROOT_PATH + "dynamic/nodeOnline.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 = 0

-# interval in minutes between data requests to the aredn node

-_DEFAULT_DATA_REQUEST_INTERVAL = 60

-# number seconds to wait for a response to HTTP request

-_HTTP_REQUEST_TIMEOUT = 10

-# 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

-# node data to a mirror server.

-_RELAY_SERVER = False

-

-   ### GLOBAL VARIABLES ###

-

-# turn on or off of verbose debugging information

-debugOption = False

-verboseDebug = 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

-# last node request time

-lastDataPointTime = -1

-

-  ###  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 getLastDataPointTime():

-    """

-    Get the timestamp of the most recent update to the round robin

-    database.

-    Parameters: none

-    Returns: string epoch time stamp of the last rrd update

-    """

-    strCmd = "rrdtool lastupdate %s" % \

-             (_RRD_FILE)

-

-    # Run the command as a subprocess.

-    try:

-        result = subprocess.check_output(strCmd, shell=True,  \

-                             stderr=subprocess.STDOUT)

-    except subprocess.CalledProcessError, exError:

-        print "%s: rrdtool update failed: %s" % \

-                    (getTimeStamp(), exError.output)

-        return None

-

-    # Return just the epoch time stamp of the last rrd update

-    return int((result.split('\n')[-2]).split(':')[0])

-##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 os.path.exists(_DUMMY_OUTPUT_FILE):

-       os.remove(_DUMMY_OUTPUT_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)

-    if os.path.exists(_DUMMY_OUTPUT_FILE):

-       os.remove(_DUMMY_OUTPUT_FILE)

-    print '%s terminating arednsig agent process' % \

-              (getTimeStamp())

-    sys.exit(0)

-##end def

-

-  ###  PUBLIC METHODS  ###

-

-def getArednNodeData():

-    """Send http request to aredn node.  The response from the

-       node contains the node signal data as unformatted ascii text.

-       Parameters: none

-       Returns: a string containing the node signal data if successful,

-                or None if not successful

-    """

-    try:

-        conn = urllib2.urlopen(arednNodeUrl, timeout=_HTTP_REQUEST_TIMEOUT)

-

-        # Format received data into a single string.

-        content = ""

-        for line in conn:

-            content += line.strip()

-        del conn

-

-    except Exception, 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 http error: %s" % (getTimeStamp(), exError)

-        return None

-

-    if verboseDebug:

-        print "http request successful: %d bytes" % len(content)

-

-    return content

-##end def

-

-def parseNodeData(sData, ldData):

-    """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

-    """

-    iTrail = int(dataRequestInterval)

-

-    try:

-        ldTmp = json.loads(sData[1:-1])

-        ldTmp = ldTmp[-iTrail:]

-        if len(ldTmp) != iTrail:

-            #raise Exception("truncated list")

-            pass

-    except Exception, exError:

-        print "%s parse failed: %s" % (getTimeStamp(), exError)

-        return False

-    

-    del ldData[:]

-    for item in ldTmp:

-        ldData.append(item)

-

-    if verboseDebug:

-        print "parse successful: %d data points" % len(ldData)

-    return True

-##end def

-

-def convertData(ldData):

-    """Convert individual node signal data items as necessary.

-       Parameters:

-           dData - a dictionary object containing the node signal data

-       Returns: True if successful, False otherwise

-    """

-    # parse example string

-    # {u'tx_mcs': u'15', u'rx_mcs': u'15', u'm': 47,

-    #  u'label': u'01/10/2020 22:17:01', u'rx_rate': u'130',

-    #  u'y': [-48, -95], u'x': 1578694621000, u'tx_rate': u'130'}

-    #

-    index = 0

-    while index < len(ldData):

-        item = ldData[index]

-        try:

-            item['time'] = int(item.pop('x')) / 1000

-            item['signal'] = int(item['y'][0])

-            item['noise'] = int(item['y'][1])

-            item['snr'] = int(item.pop('m'))

-            item['rx_mcs'] = int(item.pop('rx_mcs'))

-            item['tx_mcs'] = int(item.pop('tx_mcs'))

-            item['rx_rate'] = int(item.pop('rx_rate'))

-            item['tx_rate'] = int(item.pop('tx_rate'))

-            item.pop('y')

-            item.pop('label')

-        except Exception, exError:

-            print "%s convert data item failed: %s" % (getTimeStamp(), exError)

-            print "discarding %s" % item

-            #return False

-            ldData.pop(index)

-        else:

-            index += 1

-    ##end for

-

-    if len(ldData) > 0:

-        if verboseDebug:

-            print "convert data successful"

-        return True

-    else:

-        print "convert data failed"

-        return False

-##end def

-

-def updateDatabase(ldData):

-    """

-    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

-    """

-    updateCount = 0

-    lastDataPointTime = getLastDataPointTime()

-

-    if verboseDebug:

-         print "updating database..."

-

-    for item in ldData:

-

-        if item['time'] <= lastDataPointTime:

-            if verboseDebug:

-                print "%s invalid timestamp: discarding data" % \

-                      (getTimeStamp())

-            continue

-

-        # Format the rrdtool update command.

-        strFmt = "rrdtool update %s %s:%s:%s:%s:%s:%s:%s:%s"

-        strCmd = strFmt % (_RRD_FILE, item['time'], item['signal'], \

-                 item['noise'], item['snr'], item['rx_mcs'], \

-                 item['tx_mcs'], item['rx_rate'], item['tx_rate'])

-

-        if verboseDebug:

-            print "%s" % strCmd # DEBUG

-

-        # Run the command as a subprocess.

-        try:

-            subprocess.check_output(strCmd, shell=True,  \

-                                 stderr=subprocess.STDOUT)

-        except subprocess.CalledProcessError, exError:

-            print "%s: rrdtool update failed: %s" % \

-                        (getTimeStamp(), exError.output)

-            return False

-        updateCount += 1

-    ##end for

-

-    if debugOption:

-        print '%s added %d data points to database' % \

-              (getTimeStamp(), updateCount)

-    return True

-##end def

-

-def writeOutputDataFile(sData, ldData):

-    """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(ldData[-1]['time']) )

-    sDate = "[{\"date\":\"%s\",\"period\":\"%s\"}]" % \

-           (lastUpdate, dataRequestInterval)

-    try:

-        fc = open(_DUMMY_OUTPUT_FILE, "w")

-        fc.write(sDate)

-        fc.close()

-    except Exception, exError:

-        print "%s write node file failed: %s" % (getTimeStamp(), exError)

-        return False

-

-    if _RELAY_SERVER:

-        # Write the entire node data response to the output data file.

-        try:

-            fc = open(_OUTPUT_DATA_FILE, "w")

-            fc.write(sData)

-            fc.close()

-        except Exception, exError:

-            print "%s write output file failed: %s" % \

-                  (getTimeStamp(), exError)

-            return False

-        if verboseDebug:

-            print "write output data file: %d bytes" % len(sData)

-

-    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 LINE3:smoothed#ff0000 " \

-                  % trendWindow[gStart]

-    elif addTrend == 2:

-        strCmd += "LINE1:dSeries#0400ff "

-        strCmd += "CDEF:smoothed=dSeries,%s,TREND LINE3:smoothed#ff0000 " \

-                  % trendWindow[gStart]

-     

-    if verboseDebug:

-        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, exError:

-        print "rrdtool graph failed: %s" % (exError.output)

-        return False

-

-    if debugOption:

-        print "rrdtool graph: %s\n" % result,

-    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)

-

-    if createAllCharts:

-        createGraph('24hr_noise', 'N', 'dBm', 

-                    'Noise\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2,

-                    autoScale)

-        createGraph('24hr_rx_rate', 'RX_RATE', 'Mbps',

-                    'Rx\ Rate\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2,

-                    autoScale)

-        createGraph('24hr_tx_rate', 'TX_RATE', 'Mbps',

-                    'Tx\ Rate\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2,

-                    autoScale)

-        createGraph('24hr_rx_mcs', 'RX_MCS', 'Index',

-                    'Rx\ MCS\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2,

-                     autoScale)

-        createGraph('24hr_tx_mcs', 'TX_MCS', 'Index',

-                    'Tx\ MCS\ -\ 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)

-

-    if createAllCharts:

-        createGraph('4wk_noise', 'N', 'dBm', 

-                    'Noise\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2,

-                    autoScale)

-        createGraph('4wk_rx_rate', 'RX_RATE', 'Mbps',

-                    'Rx\ Rate\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2,

-                    autoScale)

-        createGraph('4wk_tx_rate', 'TX_RATE', 'Mbps',

-                    'Tx\ Rate\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2,

-                    autoScale)

-        createGraph('4wk_rx_mcs', 'RX_MCS', 'Index',

-                    'Rx\ MCS\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2,

-                    autoScale)

-        createGraph('4wk_tx_mcs', 'TX_MCS', 'Index',

-                    'Tx\ MCS\ -\ 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 createAllCharts:

-        createGraph('12m_noise', 'N', 'dBm', 

-                    'Noise\ -\ Past\ Year', 'end-12months', 0, 0, 2,

-                    autoScale)

-        createGraph('12m_rx_rate', 'RX_RATE', 'Mbps',

-                    'Rx\ Rate\ -\ Past\ Year', 'end-12months', 0, 0, 2,

-                    autoScale)

-        createGraph('12m_tx_rate', 'TX_RATE', 'Mbps',

-                    'Tx\ Rate\ -\ Past\ Year', 'end-12months', 0, 0, 2,

-                    autoScale)

-        createGraph('12m_rx_mcs', 'RX_MCS', 'Index',

-                    'Rx\ MCS\ -\ Past\ Year', 'end-12months', 0, 0, 2,

-                    autoScale)

-        createGraph('12m_tx_mcs', 'TX_MCS', 'Index',

-                    'Tx\ MCS\ -\ Past\ Year', 'end-12months', 0, 0, 2,

-                    autoScale)

-    if debugOption:

-        #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 debugOption, verboseDebug, dataRequestInterval, \

-           arednNodeUrl

-

-    index = 1

-    while index < len(sys.argv):

-        if sys.argv[index] == '-d':

-            debugOption = True

-        elif sys.argv[index] == '-v':

-            debugOption = True

-            verboseDebug = 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]

-            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)

-

-    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()

-

-    requestIntervalSeconds = dataRequestInterval * 60 # convert to seconds

-    chartUpdateInterval = dataRequestInterval # get charts interval

-

-    ## 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 > requestIntervalSeconds:

-            lastDataRequestTime = currentTime

-            ldData = []

-            result = True

-

-            # Get the data string from the device.

-            sData = getArednNodeData()

-            # If the first http request fails, try one more time.

-            if sData == None:

-                time.sleep(5)

-                sData = getArednNodeData()

-                if sData == None:

-                    result = False

-

-            # If successful parse the data.

-            if result:

-                result = parseNodeData(sData, ldData)

-           

-            # If parsing successful, convert the data.

-            if result:

-                result = convertData(ldData)

-

-            # If conversion successful, write data to data files.

-            if result:

-                result = updateDatabase(ldData)

-

-            if result:

-                writeOutputDataFile(sData, ldData)

-

-            # 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 debugOption:

-            if result:

-                print "%s update successful:" % getTimeStamp(),

-            else:

-                print "%s update failed:" % getTimeStamp(),

-            print "%6f seconds processing time\n" % elapsedTime 

-        remainingTime = requestIntervalSeconds - elapsedTime

-        if remainingTime > 0.0:

-            time.sleep(remainingTime)

-    ## end while

-    return

-## end def

-

-if __name__ == '__main__':

-    try:

-        main()

-    except KeyboardInterrupt:

-        print '\n',

-        terminateAgentProcess('KeyboardInterrupt','Module')

new file mode 100755

@@ -0,0 +1,701 @@

+#!/usr/bin/python -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.

+#

+#2345678901234567890123456789012345678901234567890123456789012345678901234567890

+

+import os

+import urllib2

+import sys

+import signal

+import subprocess

+import multiprocessing

+import time

+import json

+

+_USER = os.environ['USER']

+_HOSTNAME = os.uname()[1]

+

+   ### DEFAULT AREDN NODE URL ###

+

+# set url of the aredn node

+

+_DEFAULT_AREDN_NODE_URL = "http://localnode:8080/cgi-bin/signal.json"

+

+    ### 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/arednsigOutputData.js"

+# dummy output data file

+_DUMMY_OUTPUT_FILE = _DOCROOT_PATH + "dynamic/nodeOnline.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 = 0

+# interval in minutes between data requests to the aredn node

+_DEFAULT_DATA_REQUEST_INTERVAL = 60

+# number seconds to wait for a response to HTTP request

+_HTTP_REQUEST_TIMEOUT = 10

+# 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

+# node data to a mirror server.

+_RELAY_SERVER = False

+

+   ### GLOBAL VARIABLES ###

+

+# turn on or off of verbose debugging information

+debugOption = False

+verboseDebug = 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

+# last node request time

+lastDataPointTime = -1

+

+  ###  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 getLastDataPointTime():

+    """

+    Get the timestamp of the most recent update to the round robin

+    database.

+    Parameters: none

+    Returns: string epoch time stamp of the last rrd update

+    """

+    strCmd = "rrdtool lastupdate %s" % \

+             (_RRD_FILE)

+

+    # Run the command as a subprocess.

+    try:

+        result = subprocess.check_output(strCmd, shell=True,  \

+                             stderr=subprocess.STDOUT)

+    except subprocess.CalledProcessError, exError:

+        print "%s: rrdtool update failed: %s" % \

+                    (getTimeStamp(), exError.output)

+        return None

+

+    # Return just the epoch time stamp of the last rrd update

+    return int((result.split('\n')[-2]).split(':')[0])

+##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 os.path.exists(_DUMMY_OUTPUT_FILE):

+       os.remove(_DUMMY_OUTPUT_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)

+    if os.path.exists(_DUMMY_OUTPUT_FILE):

+       os.remove(_DUMMY_OUTPUT_FILE)