logparser.pl
logparser.pl [-f configFile] [-p processes] [-s storeFile] [-o propertiesFile] [-l log4perlFile] [-k lockFile] [-I path/to/lib1 -I path/to/lib2]
Parses a log file
logparser.pl -h
Shows the help man page
logparser.pl -v
shows the version
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:
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
See the -f option. But mainly you need to specify the log file to parse and the subclass of LogparserDriver to use.
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
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.
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
All the command line options override the options in the configuration file.
Indicates the configuration file. There is no corresponding configuration file option. The default value is "/etc/logparser/logparser.conf".
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
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.
Indicates the configuration file for the Log4Perl configuration file. The corresponding configuration file option is "log4perlFile". The default value is "/etc/logparser/log4perl.conf"
Indicates the lock file. The corresponding configuration file option is "lockFile". The default value is "/tmp/.logparser.lockfile"
Indicates the properties file. The corresponding configuration file option is "propertiesFile". The default value is "/var/lib/logparser/logparser.properties"
Use this to include alternative paths to find Logparser Drivers to avoid setting shell variables when running logparser
Shows this help page
Shows the version of the script.
The configuration tag used is "logparser::Default"
This option specifies the log4perl settings for logs. See the Log::Log4perl documentation.
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
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 SNMP::LogparserDriver::ProxyLog; use warnings; use Log::Log4perl; use parent 'SNMP::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
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
parent
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
Nito Martinez <Nito at Qindel dot ES>
5/5/2005
Copyright 2007-2011 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.
To install SNMP::LogParser, copy and paste the appropriate command in to your terminal.
cpanm
cpanm SNMP::LogParser
CPAN shell
perl -MCPAN -e shell install SNMP::LogParser
For more information on module installation, please visit the detailed CPAN module installation guide.