Yum

#!/usr/bin/perl -w
#
# This script determines the number of outstanding updates (patches) for this
# RHEL host. The count is reported to the Xymon monitoring server. This script
# requires that:
#  A- the yum-security plug-in is installed, and
#  B- that sudo is configured to have this script run `yum`.
#
# Written by W.J.M. Nelis, wim.nelis@nlr.nl
#
use strict ;
use Time::Piece ;                       # Format time

#
# Installation constants.
#
my $XyDisp= exists $ENV{XYMSRV} ? $ENV{XYMSRV} : $ENV{XYMONSERVERHOSTNAME} ;
my $XySend= $ENV{XYMON} ;               # Monitor interface program
my $XyLife= '+13h' ;                    # Status lifetime, default 30m
my $FmtDate= "%Y.%m.%d %H:%M:%S" ;      # Default date format
   $FmtDate= $ENV{XYMONDATEFORMAT} if exists $ENV{XYMONDATEFORMAT} ;
my $TestName= 'update' ;                # Test name

my @ColourOf= ( 'red', 'yellow', 'clear', 'green' ) ;
#
# Define the names and the status colours for the various classes of updates.
# The names are chosen such that the order sorted on name matches an increased
# urge to install.
#
my %Class= (
     'anonymous'        => [ 'Anonymous',   2 ],        # Catch undefined classes
     'bugfix'           => [ 'Bugfix',      3 ],
     'enhancement'      => [ 'Enhancement', 3 ],
     'Low/Sec.'         => [ 'Low',         3 ],
     'Moderate/Sec.'    => [ 'Moderate',    1 ],
     'Important/Sec.'   => [ 'Serious',     1 ],
     'Critical/Sec.'    => [ 'Vulnerable',  0 ],
     'security'         => [ 'Vulnerable',  0 ],
   ) ;
  $Class{$Class{$_}[0]}= $Class{$_}     foreach ( keys %Class ) ;

#
# Variable $YumCmd defines the shell command to retrieve the list of outstanding
# patches. The return codes of this command are:
#    0 - no updates
#    1 - error
#  100 - updates available
# Variable $YumClass defines the shell command to retrieve a list of updates,
# including the classification of each of the updates. This list contains
# duplicates of updates which are NOT listed by check-update!
#
my $YumCmd  = 'sudo yum check-update  2>&1' ;   # Retrieve list of patches
my $YumClass= 'sudo yum list-security 2>&1' ;   # Retrieve list of classifications

#
# Global variable allocation.
#
my $Now= localtime ;                    # Timestamp of tests
   $Now= $Now->strftime( $FmtDate ) ;
my $Colour= 3 ;                         # Test status
my $SubColour ;                         # Status of one update class
my $HostName = `hostname` ;             # Host under test
   chomp $HostName ;
my $Result ;                            # Status message for xymon
my $Count ;                             # Number of updates
my %Update= () ;                        # List of updates
my $Update ;                            # Full name of an update
my %ClassLst= () ;                      # List of updates per class
my %ClassCnt= () ;                      # Updates per class
my $Class ;                             # Classification of an update
my @Lines ;                             # Output of $YumCmd
my $Lines ;                             # Concatenated output
my (@PrvLine,@Fields) ;                 # Field on a line image

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

#
# Function InformXymon sends the message, in global variable $Result, to the
# xymon server.
#
sub InformXymon() {
  $Result= "\"status$XyLife $HostName.$TestName $ColourOf[$Colour] $Now\n" .
           "$Result\"\n" ;
  `$XySend $XyDisp $Result` ;           # Inform Xymon

  $Result= '' ;                         # Reset message parameters
  $Colour=  3 ;
}  # of InformXymon

##
## M A I N   P R O G R A M
## -----------------------
##

@Lines = `$YumCmd` ;                    # Retrieve list of updates
$Lines = join( '', @Lines ) ;           # Single string for error checks
$Result= undef ;                        # Preset message for Xymon

#
# Check the output of the command for some error conditions.
#
if ( @Lines == 0 ) {
  $Colour= 2 ;                  # Measurement failed
  $Result= 'No update status received' ;
} elsif ( $Lines[0] !~ m/^Loaded plugins/ ) {
  $Colour= 2 ;                  # Measurement failed
  $Result= "Unexpected update status received:\n" ;
  foreach ( @Lines ) {
    chomp ;
    $Result.= "  $_\n" ;
  }  # of foreach
} elsif ( $Lines =~ m/run this command as root/ ) {
  $Colour= 2 ;
  $Result= 'No update status received, insufficient privileges' ;
} elsif ( $Lines=~ m/There was an error communicating with RHN/ ) {
  $Colour= 2 ;
  $Result= 'Communication with RHN failed' ;
} else {

  $ClassCnt{$Class{$_}[0]}= 0   foreach ( keys %Class ) ;
  $Count= 0 ;
#
# Check the output for the number of outstanding updates.
#
  unless ( defined $Result ) {
    foreach ( @Lines ) {
      chomp ;
      last                      if m/^Obsoleting Packages/ ;
      @Fields= split ;

 # Handle an incomplete line. If the name or the version number are long
 # strings, the fields may be presented on two lines in stead of one.
      if ( @Fields < 3 ) {
        if ( @PrvLine ) {
          unshift @Fields, @PrvLine ;
        } else {
          @PrvLine= @Fields ;
          next ;
        }  # of else
      }  # of if
      @PrvLine= () ;

      next                      unless @Fields == 3 ;
      next                      unless $Fields[1] =~ m/^\d/ ;
      $Count++ ;
      $Update= $Fields[0] ;             # Short name of update
      $Update= "$1-$Fields[1].$2"       if $Update =~ m/^(.+)\.(.+?)$/ ;
#     print STDERR "$Update\n" ;        # Log...
      $Update{$Update}= 'Anonymous' ;   # Set classification
    }  # of foreach

#
# Go retrieve the classification of each update and count the number of
# available updates in each class.
#
    @Lines= `$YumClass` ;
    foreach ( @Lines ) {
      chomp ;
      @Fields= split ;
      next                      unless @Fields == 3 ;
      next                      unless exists $Update{$Fields[2]} ;

      $Class= $Fields[1] ;              # Classification
      unless ( exists $Class{$Class} ) {
        print "$Now Unknown class '$Class'\n" ;
      }  # of unless
      $Class= exists $Class{$Class} ? $Class{$Class}[0] : 'Anonymous' ;
      $Update{$Fields[2]}= $Class ;     # Save classification
      push @{$ClassLst{$Class}}, "$Fields[0]  $Fields[2]"       unless $Class eq 'Anonymous' ;
    }  # of foreach
    $ClassCnt{$Update{$_}}++    foreach ( keys %Update ) ;
#
# The list of updates in class "Anonymous" must be build seperately.
#
    if ( $ClassCnt{Anonymous} ) {
      foreach ( sort keys %Update ) {
        next                    unless $Update{$_} eq 'Anonymous' ;
        push @{$ClassLst{Anonymous}}, "RHNA-0000:0000  $_" ;
      }  # of foreach
    }  # of if

#
# Build a table showing the results.
#
    $Result = "<table>\n" ;
    $Result.= " <tr><th align='left'>Category</th><th>Count</th><th>Status</th></tr>\n" ;
    foreach $Class ( sort keys %ClassCnt ) {
      $SubColour= $ClassCnt{$Class} == 0 ? 3 : $Class{$Class}[1] ;
      $Colour   = min( $Colour, $SubColour ) ;
      $SubColour= $ColourOf[$SubColour] ;
      $ClassLst{$Class}= [ 'None' ]     unless exists $ClassLst{$Class} ;
      $Result.= " <tr><td><span title='" ;
      $Result.= join( "\n", @{$ClassLst{$Class}} ) ;
      $Result.= "'>$Class</span></td>" .
                "<td align='right'>$ClassCnt{$Class}</td>" .
                "<td>   &$SubColour</tr>\n" ;
    }  # of foreach

    $Result.= " <tr><td>&nbsp;</td><td>-----</td><td>&nbsp;</td></tr>\n" ;
    $Result.= " <tr><td>Total</td><td align='right'>$Count</td><td>   &$ColourOf[$Colour]</td></tr>\n" ;
    $Result.= "</table>\n" ;
  }  # of unless
}  # of else

$Result= "<b>Yum update status</b>\n" .
         "\n\n" . $Result . "\n" ;
InformXymon ;