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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
_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/status"
### 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 ###
# interval in minutes between data requests to the aredn node
_DEFAULT_DATA_REQUEST_INTERVAL = 1
# chart update interval in minutes
_CHART_UPDATE_INTERVAL = 10
# number seconds to wait for a response to HTTP request
_HTTP_REQUEST_TIMEOUT = 10
# max number of failed data requests allowed
_MAX_FAILED_DATA_REQUESTS = 0
# 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
# chart update interval
chartUpdateInterval = _CHART_UPDATE_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 getEpochSeconds(sTime):
"""Convert the time stamp supplied in the weather data 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, 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 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, dData):
"""Parse the node status page html 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
"""
try:
# Set search boundaries for signal data
strBeginSearch = '<nobr>Signal/Noise/Ratio</nobr></th>' \
'<td valign=middle><nobr><big><b>'
strEndSearch = 'dB'
iBeginIndex = sData.find(strBeginSearch) + len(strBeginSearch)
iEndIndex = sData.find(strEndSearch, iBeginIndex)
# Exception if signal data not found
if iBeginIndex == -1 or iEndIndex == -1:
raise Exception("signal data not found in status page")
# Extract signal data from html
snr = sData[iBeginIndex:iEndIndex]
snr = snr.replace(' ','')
lsnr = snr.split('/')
# Store time and signal data in dictionary object
dData['time'] = getEpochSeconds(getTimeStamp())
dData['signal'] = lsnr[0]
dData['noise'] = lsnr[1]
dData['snr'] = lsnr[2]
except Exception, exError:
print "%s parse failed: %s" % (getTimeStamp(), exError)
return False
if verboseDebug:
print "parse successful"
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 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
return True
##end def
def writeOutputDataFile(sData, 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']) )
sDate = "[{\"date\":\"%s\",\"period\":\"%s\"}]" % \
(lastUpdate, chartUpdateInterval)
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)
# 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 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
## Get command line arguments.
getCLarguments()
requestIntervalSeconds = dataRequestInterval * 60 # convert to seconds
chartUpdateIntervalSeconds = chartUpdateInterval * 60 # 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
dData = {}
result = True
# Get the data string from the device.
sData = getArednNodeData()
# If the first http request fails, try one more time.
if sData == None:
result = False
# If successful parse the data.
if result:
result = parseNodeData(sData, dData)
# If parse successful, write data to data files.
if result:
result = updateDatabase(dData)
if result:
writeOutputDataFile(sData, 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 > chartUpdateIntervalSeconds:
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')
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