NAME

logparser.pl

SYNOPSIS

logparser.pl [-f configFile] [-p processes] [-s storeFile] [-o propertiesFile] [-l log4perlFile]

Parses a log file

logparser.pl -h

Shows the help man page

logparser.pl -v

shows the version

DESCRIPTION

The logparser script is supposed to be used from cron and to parse log files every five minutes starting from the last position read. It should take in account files that are rotated.

The main configuration comes from the configuration file (see the -f switch in the OPTIONS section).

The main parsing of any log file should be accomplished by creating an inherited class from the class LogparserDriver which has methods for specifying the regular expression, the evalBegin, evalIterate and evalEnd method.

By default the process is the following:

SETTING UP THE LOGPARSER

# Create a subclass of the LogparserDriver.

You need to implement at least define the variable pattern (the regular expression), and the methods evalBegin, evalIterate (invoked for each line of the file) and evalEnd.

For an exact description of the methods please see LogparserDriver

# Create a configuration file for logparser.

See the -f option. But mainly you need to specify the log file to parse and the subclass of LogparserDriver to use.

# (Optional) Set up the log configuration in log4perl.conf

The default logging entry for logparser uses the tag "logparser" and the LogparserDriver uses "logparser.LogparserDriver" tag. That is any subclass of LogparserDriver (including LogparserDriver itself) uses as the logging tag: "logparser.classname". For more information about logging please see Log::Log4perl

# Set up the logparser to run from cron

This can usually be achieved by creating a cron entry like this (please check the syntax for your exact *nix system):

$ crontab -e

*/5 * * * * [ -x /usr/bin/logparser ] && /usr/bin/logparser

Please be aware that the logfile should be possible to read as the user you are running cron from.

PROCESS OF LOGPARSER

The logparser works as follows

• Firstly it gets all the options.

  More precedence have the command line options, then the options specified in the configuration file and finally the options defined by default.

• Get the saved configuration

  All the configuration specified in the LogparserDriver class in the savespace method are restored from the storeFile including also the seek position of each logfile parsed.

• Create lock file

  In this step a lock file is created (see lockFile option). The file is created with an exclusive lock with the PID (Process Identifier) in it.

  If the file exists then it is checked if a process with the recorded process id exists, if not the file is deleted and the process continued. Otherwise the process stops assuming that during the next cron invocation the process will be restored.

• Process each log

  For each log specified in the configuration file the class specified in the configuration file is invoked with methods:

  • evalBegin before the line parsing begins

  • evalIterate for each line of the log. Starting in the position of the last line parsed.

  • evalEnd after the parsing ends

• Output the properties method

  Everything saved during evalBegin, evalIterate or evalEnd in the properties method of LogparserDriver will be output into the propertiesFile file of the configuration file (or command line).

• The savespace is saved

  The savespace variable of the sub class LogparserDriver and the position of the logfile will be saved.

• The lockFile is removed

OPTIONS

All the command line options override the options in the configuration file.

COMMAND LINE OPTIONS

-f configuration file

Indicates the configuration file. There is no corresponding configuration file option. The default value is "/etc/logparser/logparser.conf".

-p number of processes

Indicates how many concurrent processes should be run in parallel. The corresponding configuration file option is "processes".

The default value is 1.

This option is not implemented yet

-s storeFile

Indicates in which file the %properties hash should be stored. This has will be stored in a Java properties file in pairs of key=value pairs

For more information please see the LogparserDriver page.

-l log4perlFile

Indicates the configuration file for the Log4Perl configuration file. The corresponding configuration file option is "log4perlFile". The default value is "/etc/logparser/log4perl.conf"

-h

Shows this help page

-v

Shows the version of the script.

CONFIG FILE OPTIONS

The configuration tag used is "logparser::Default"

log4perl

This option specifies the log4perl settings for logs. See the Log::Log4perl documentation.

log

Specifies all the logs that should be parsed. Each "<KEY>" indicates a different log. The different entries that can be used are:

* log.<KEY>.name: name identifies the log entry. By default the name defaults to "<KEY>". Be aware that the name is used to identify the log position. That is if you change the name (or the key if you don't define the name) then the log will be parsed from the beginning

* log.<KEY>.file: This is the file that should be parsed. This file should always be defined.

* log.<KEY>.driver: This is the class that should be invoked to parse the file specified above. Please be aware that the class should be a subclass of LogparserDriver class

EXAMPLE

We will provide here a detailed example on how to parse a particular file:

Assume that we want to get the number of email messages sent and include the size of these email messages.

An example input line of the log file /var/log/maillog could be:

Sep  4 11:50:03 localhost sendmail[4091]: k849o3DZ004091: from=root, size=236, class=0, nrcpts=1, msgid=<200609040950.k849o3DZ004091@localhost.localdomain>, relay=root@localhost

The output of the incremental parsing that we want to record should be registered in a file /var/lib/logparser/logparser.properties with the values:

mailMessages=23
sizeOfMailMessages=52354

The steps that we will follow are:

• Create a subclass of the LogparserDriver

  We need to define the following regular expression to match the log file:

  from=\S+,\s+size=(\d+),

  We create a the file /usr/lib/LogparserDriver/MailLog.pm

  with the following content:

  package LogparserDriver::ProxyLog;
  
  use warnings;
  use Log::Log4perl;
  use LogparserDriver;
  
  @LogparserDriver::ProxyLog::ISA = ('LogparserDriver');
  
  # Class constructor
  sub new {
   my $class = shift;
   my $self  = $class->SUPER::new();
   bless ($self, $class);
   $self->pattern('from=\S+,\s+size=(\d+),');
   return $self;
  }
  
  # Everything in savespace will be preserved
  # across different invocations of logparser
  sub evalBegin {
   my $self = shift;
   $self->{savespace}{mailMessages} = 0 if (!defined($self->{savespace}{mailMessages}));
   $self->{savespace}{sizeOfMailMessages} = 0 if (!defined($self->{savespace}{sizeOfMailMessages}));
  }
  
  sub evalIterate {
   my $self = shift;
   my ($line) = @_;
   my $pattern = $self->{pattern};
   if ($line =~ /$pattern/) {
     my ($size) = ($1);
     $self->{savespace}{mailMessages} ++;
     $self->{savespace}{sizeOfMailMessages} += $size;
  }
  }
  
  # Everything saved in the properties hash will be output
  # in /var/lib/logparser/logparser.properties
  # (depending on the log file)
  sub evalEnd {
   my $self = shift;
   $self->{properties} = 
     [ 'mailMessages' => $self->{savespace}{mailMessages},
       'sizeOfMailMessages' => $self->{savespace}{sizeOfMailMessages}
     ];
  }

• Create a configuration file for logparser.

  We will the following configuration file in /etc/logparser/logparser.conf:

  # storeFile
  # Indicates which file should be used to save %savespace hash
  # By default it is /var/lib/logparser/logparser.store
  storeFile=/var/lib/logparser/logparser.store
  
  # propertiesFile
  # Indicates which file should store the properties
  # generated by the driver
  # By default it is /var/lib/logparser/logparser.properties
  propertiesFile=/var/lib/logparser/logparser.properties
  
  # log to be monitored.
  # For each log you can add several patterns, each one 
  # The work space variable that you must use is $workspace{'name1'}
  # Everything that you save in $savespace{'name1'} will be maintained
  # across sessions.
  log.maillog.name: maillog
  log.maillog.file: /var/log/maillog
  log.maillog.driver: LogparserDriver

• Set up the logparser to run from cron

  */5 * * * * [ -x /usr/bin/logparser ] && /usr/bin/logparser

REQUIREMENTS and LIMITATIONS

INSTALLATION

Required Perl packages

The perl packages installed for this script are:

• Storable

• Config-Find-0.15

• File-Temp-0.14

• File-HomeDir-0.05

• File-Which-0.05

• Config-Properties-Simple-0.09

• Proc::ProcessTable

• Log::Dispatch::FileRotate

BUGS

• When following situation ocurrs some entry lines might not be parsed

  1) When the size of the log file during parse n is greater than the size of the log during parse n+1 and the log has been rotated in the mean time.

• When the machine reboots and the lock file is not stored in a tempfs it might happen that another process has started with the pid stored in the lock file. The workaround is to store the lock file in /tmp

TODO

- Allow for non line oriented parsing ($/)

- Save the configuration in the store hash and use only the parsing of options when specified in the command line.

SEE ALSO

strftime(3) man page for specifying the directory/log which should be parsed.

Log::Log4perl For the logging configuration

LogparserDriver For the default driver for parsing logs

AUTHOR

Nito Martinez <Nito at Qindel dot ES>

5/5/2005

COPYRIGHT & LICENSE

Copyright 2007 by Qindel Formacion y Servicios SL, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm SNMP::LogParser

perl -MCPAN -e shell
install SNMP::LogParser