retmt: RETrieve Machine Temperature

Author Wim Nelis
Compatibility Xymon 4.2
Requirements Perl
Download None
Last Update 2017-10-18

This client-side script retrieves the CPU and GPU temperatures of a Raspberry Pi 3 and reports them to the xymon server. A rather generic way of reporting the values is used, in which the minimum, the maximum and the average temperature are reported. The graph shows the range of the temperatures (a 100% confidence interval) and the average of the temperatures. (This method is usable for an arbitrary number of temperature sensors. It is used to report the temperatures of a switch with 29 temperature sensors.)

At the client side the script and the invocation of the script need to be installed. On the server side an extension of the RRD definitions, an extension of the graph definitions and a configuration of this test in xymon server are needed.

Client side

The script, written in Perl, is installed in (copied to) file ~xymon/client/ext/retmt.pl, typically /usr/lib/xymon/client/ext/retmt.pl.

retmt.pl

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#!/usr/bin/perl -w
#
# RETrieve_Machine_Temperature, retmt:
#  Retrieve the temperatures measured within the RPI3 machine and report
#  them to Xymon.
#
# Written by W.J.M. Nelis, wim.nelis@ziggo.nl, 2017.10
#
use strict ;
use Time::Piece ;			# Format time

#
# Installation constants.
# -----------------------
#
my $XyDisp= $ENV{XYMSRV} ;		# Name of monitor server
my $XySend= $ENV{XYMON} ;		# Monitor interface program
my $FmtDate= "%Y.%m.%d %H:%M:%S" ;	# Default date format
   $FmtDate= $ENV{XYMONDATEFORMAT} if exists $ENV{XYMONDATEFORMAT} ;
my $HostName= `hostname` ;		# 'Source' of this test
chomp $HostName ;
my $TestName= 'env' ;			# Test name
my $ThresholdYellow= 50 ;		# Warning threshold [C]
my $ThresholdRed   = 60 ;		# Error threshold [C]

my @ColourOf= ( 'red', 'yellow', 'clear', 'green' ) ;

my $CpuFil= '/sys/class/thermal/thermal_zone0/temp' ;
my $GpuCmd= '/usr/bin/vcgencmd measure_temp' ;

#
# Global variables.
# -----------------
#
my $Now= localtime ;			# Timestamp of tests
   $Now= $Now->strftime( $FmtDate ) ;
my $Colour=  3 ;			# Test status
my $Result= '' ;			# Message to sent to Xymon
my %Temp ;				# Temperature readings

my %ErrMsg ;				# Error messages
   $ErrMsg{$_}= []		foreach ( @ColourOf ) ;

#
# Issue a message the the logfile. As this script is run periodically by Xymon,
# StdOut will be redirected to the logfile.
#
sub LogMessage {
  my $Msg= shift ;
  my @Time= (localtime())[0..5] ;
  $Time[4]++ ;  $Time[5]+= 1900 ;
  chomp $Msg ;
  printf "%4d%02d%02d %02d%02d%02d %s\n", reverse(@Time), $Msg ;
}  # of LogMessage

sub max($$) { return $_[0] > $_[1] ? $_[0] : $_[1] ; }
sub min($$) { return $_[0] < $_[1] ? $_[0] : $_[1] ; }

#
# Function InformXymon sends the message, in global variable $Result, to
# the Xymon server. Any error messages in %ErrMsg are prepended to the message
# and the status (colour) of the message is adapted accordingly.
#
sub InformXymon() {
  my $ErrMsg= '' ;
  my $Clr ;				# Colour of one sub-test

  for ( my $i= 0 ; $i < @ColourOf ; $i++ ) {
    $Clr= $ColourOf[$i] ;
    next			unless @{$ErrMsg{$Clr}} ;
    $Colour= min( $Colour, $i ) ;
    $ErrMsg.= "&$Clr $_\n"	foreach ( @{$ErrMsg{$Clr}} ) ;
  }  # of foreach
  $ErrMsg.= "\n"		if $ErrMsg ;

  $Colour= $ColourOf[$Colour] ;
  $Result= "\"status $HostName.$TestName $Colour $Now\n" .
	   "<b>Temperature sensor readings</b>\n\n" .
           "$ErrMsg$Result\"\n" ;
  `$XySend $XyDisp $Result` ;           # Inform Xymon

  $Result= '' ;                         # Reset message parameters
  $Colour=  3 ;
  $ErrMsg{$_}= []		foreach ( @ColourOf ) ;
}  # of InformXymon

#
# Function ReadSensors retrieves the temperatures and their thresholds. The
# results are stored in hash %Temp. In case of an error, the result area
# will be empty.
#
sub ReadSensors() {
  my @Lines ;				# Content of one 'file'

  %Temp= () ;				# Clear result area
  unless ( defined open(FH,'<',$CpuFil) ) {
    push @{$ErrMsg{clear}}, "Cannot read CPU temperature from $CpuFil:\n" .
			    "  $!" ;
  } else {
    @Lines= <FH> ;			# Read entire file
    unless ( @Lines == 1  and  $Lines[0] =~ m/^(\d+)/ ) {
      push @{$ErrMsg{clear}}, "Cannot read CPU temperature from $CpuFil\n:" .
			      "  Unexpected input" ;
    } else {
      $Temp{CPU}{label}= 'CPU' ;
      $Temp{CPU}{input}= sprintf( '%.1f', $1/1000 ) ;
      $Temp{CPU}{max}  = $ThresholdYellow ;
      $Temp{CPU}{crit} = $ThresholdRed ;
    }  # of else
  }  # of else

  @Lines= `$GpuCmd` ;			# Retrieve information
  if ( @Lines == 0 ) {
    push @{$ErrMsg{clear}}, "Cannot read GPU temperature from $GpuCmd:\n" .
			    "  no data returned" ;
  } else {
    chomp $Lines[0] ;
    unless ( $Lines[0] =~ m/^temp=([\d\.]+).+C$/ ) {
      push @{$ErrMsg{clear}}, "Cannot read GPU temperature from $GpuCmd:\n" .
			      "  unexpected input : $Lines[0]" ;
    } else {
      $Temp{GPU}{label}= 'GPU' ;
      $Temp{GPU}{input}= $1 ;
      $Temp{GPU}{max}  = $ThresholdYellow ;
      $Temp{GPU}{crit} = $ThresholdRed ;
    }  # of else
  }  # of else
}  # of ReadSensors

#
# Function BuildMessage formats the collected data into a nice table, performs
# the threshold checks and leaves the results in the status indicator. The
# statistics are added in the DEVMON format to be moved into an RRD.
#
sub BuildMessage() {
  my ($TempMin,$TempAvg,$TempMax)= (100,0,-100) ;	# Temperature statistics
  my $T ;				# Ref to data of one sensor
  my $Clr ;				# Status (colour) of one reading

  if ( scalar(keys %Temp) == 0 ) {
    $Result= "No data received\n" ;
    return ;
  }  # of if

 #
 # Build a table showing the various sensors, their readings and their
 # thresholds.
 #
  $Result = "<table border=1 cellpadding=5>\n" ;
  $Result.= " <tr> <th>Sensor</th> <th>Temp [C]</th> <th>Threshold [C]</th> </tr>\n" ;
  foreach ( sort keys %Temp ) {
    $T= $Temp{$_} ;			# Ref to sensor data
    $Result.= " <tr> " ;
    $Result.= "<td>$$T{label}</td> " ;	# Name of sensor

    $TempMin= min( $TempMin, $$T{input} ) ;
    $TempMax= max( $TempMax, $$T{input} ) ;
    $TempAvg+= $$T{input} ;

    $Clr= 'green' ;			# Assume temperature in range
    if      ( $$T{input} < 10 ) {	# Temperature is too low
      $Clr= 'yellow' ;
      push @{$ErrMsg{$Clr}}, "Temperature of $$T{label} is low" ;
    } elsif ( $$T{input} >= $$T{crit} ) {
      $Clr= 'red' ;
      push @{$ErrMsg{$Clr}}, "Temperature of $$T{label} is too high" ;
    } elsif ( $$T{input} >= $$T{max}  ) {
      $Clr= 'yellow' ;
      push @{$ErrMsg{$Clr}}, "Temperature of $$T{label} is high" ;
    }  # of elsif

    $Result.= "<td align='right'>$$T{input} &$Clr</td> " ;
    $Result.= "<td align='right'>$$T{max}</td> " ;
    $Result.= "</tr>\n" ;
  }  # of foreach
  $Result.= "</table>\n" ;
  $TempAvg/= scalar( keys %Temp ) ;	# Average temperature
  $TempAvg = sprintf( '%5.1f', $TempAvg ) ;

 #
 # Append the statistics, using the DEVMON format.
 #
  $Result.= "<!-- linecount=1 -->\n" ;
  $Result.= "<!--DEVMON RRD: env 0 0\n" ;
  $Result.= "DS:Temperature:GAUGE:600:-100:100 DS:MinTemp:GAUGE:600:-100:100 DS:MaxTemp:GAUGE:600:-100:100\n" ;
  $Result.= "temp $TempAvg:$TempMin:$TempMax\n" ;
  $Result.= "-->" ;
}  # of BuildMessage


#
# ----- MAIN PROGRAM -----
#
ReadSensors ;
BuildMessage ;
InformXymon ;

Script retmt.pl is invoked once every 5 minutes. This is configured by copying the snippet below to file ~xymon/client/etc/clientlaunch.d/retmt.cfg and restarting the xymon client.

#
# Test retmt retrieves the temperatures of this machine.
#
[retmt]
	ENVFILE $XYMONCLIENTHOME/etc/xymonclient.cfg
	CMD $XYMONCLIENTHOME/ext/retmt.pl
	LOGFILE $XYMONCLIENTLOGS/retmt.log
	INTERVAL 5m

Server side

Before any data is captured in an RRD, the definition of the RRD needed for this monitor needs to be installed. Add the snippet below to file ~xymon/server/etc/rrddefinitions.cfg, somewhere before the default setup.

# Definition for the measurement of the environmental temperature(s).
# Besides the average the minimum and the maximum are measured, and
# thus the MIN and MAX consolidation functions are needed too.
[env]
	RRA:AVERAGE:0.5:1:576
	RRA:AVERAGE:0.5:6:576
	RRA:AVERAGE:0.5:24:576
	RRA:AVERAGE:0.5:288:576
	RRA:MIN:0.5:1:576
	RRA:MIN:0.5:6:576
	RRA:MIN:0.5:24:576
	RRA:MIN:0.5:288:576
	RRA:MAX:0.5:1:576
	RRA:MAX:0.5:6:576
	RRA:MAX:0.5:24:576
	RRA:MAX:0.5:288:576

Next the graph definition shown below is saved in file ~xymon/server/etc/graphs.d/graphs.retmt.cfg.

#
# Graph definitions for test 'env'.
#
[env]
	TITLE , temperature  
	YAXIS Temperature [C]
	-l 0
	DEF:temp=env.temp.rrd:Temperature:AVERAGE
	DEF:tmin=env.temp.rrd:MinTemp:MIN
	DEF:tmax=env.temp.rrd:MaxTemp:MAX
	CDEF:trng=tmax,tmin,-
	LINE1:tmin#ffa07a
	AREA:trng#ffa07a::STACK
	LINE1:temp#EE0000:Average
	GPRINT:tmin:MIN:Min \: %5.1lf C
	GPRINT:tmax:MAX:Max \: %5.1lf C
	GPRINT:temp:AVERAGE:Avg \: %5.1lf C
	GPRINT:temp:LAST:Cur \: %5.1lf C\n

The definition file xymonserver.cfg is extended by copying the snippet below to file ~xymon/server/etc/xymonserver.d/env.cfg. It specifies that the status message for test named 'env' uses the DEVMON format to pass measurements.

TEST2RRD+=",env=devmon"
GRAPHS+=",env"
  • 2017-10-18
    • Initial release
  • monitors/retmt.txt
  • Last modified: 2017/10/18 11:01
  • by wnelis