Log Module

There is a global log interface for OTOBO that provides the possibility to create own log back ends.

Writing an own logging back end is as easy as reimplementing the Kernel::System::Log::Log() method.

Log Module Code Example

In this small example, we’ll write a little file logging back end which works similar to Kernel::System::Log::File, but prepends a string to each logging entry.

# --
# Copyright (C) 2019-2021 Rother OSS GmbH, https://otobo.de/
# --
# This software comes with ABSOLUTELY NO WARRANTY. For details, see
# the enclosed file COPYING for license information (GPL). If you
# did not receive this file, see https://www.gnu.org/licenses/gpl-3.0.txt.
# --

package Kernel::System::Log::CustomFile;

use strict;
use warnings;

umask "002";

sub new {
    my ( $Type, %Param ) = @_;

    # allocate new hash for object
    my $Self = {};
    bless( $Self, $Type );

    # get needed objects
    for (qw(ConfigObject EncodeObject)) {
        if ( $Param{$_} ) {
            $Self->{$_} = $Param{$_};
        else {
            die "Got no $_!";

    # get logfile location
    $Self->{LogFile} = '/var/log/CustomFile.log';

    # set custom prefix
    $Self->{CustomPrefix} = 'CustomFileExample';

    # Fixed bug# 2265 - For IIS we need to create a own error log file.
    # Bind stderr to log file, because IIS do print stderr to web page.
    if ( $ENV{SERVER_SOFTWARE} && $ENV{SERVER_SOFTWARE} =~ /^microsoft\-iis/i ) {
        if ( !open STDERR, '>>', $Self->{LogFile} . '.error' ) {
            print STDERR "ERROR: Can't write $Self->{LogFile}.error: $!";

    return $Self;

sub Log {
    my ( $Self, %Param ) = @_;

    my $FH;

    # open logfile
    if ( !open $FH, '>>', $Self->{LogFile} ) {

        # print error screen
        print STDERR "\n";
        print STDERR " >> Can't write $Self->{LogFile}: $! <<\n";
        print STDERR "\n";

    # write log file
    print $FH '[' . localtime() . ']';
    if ( lc $Param{Priority} eq 'debug' ) {
        print $FH "[Debug][$Param{Module}][$Param{Line}] $Self->{CustomPrefix} $Param{Message}\n";
    elsif ( lc $Param{Priority} eq 'info' ) {
        print $FH "[Info][$Param{Module}]  $Self->{CustomPrefix} $Param{Message}\n";
    elsif ( lc $Param{Priority} eq 'notice' ) {
        print $FH "[Notice][$Param{Module}] $Self->{CustomPrefix} $Param{Message}\n";
    elsif ( lc $Param{Priority} eq 'error' ) {
        print $FH "[Error][$Param{Module}][$Param{Line}] $Self->{CustomPrefix} $Param{Message}\n";
    else {

        # print error messages to STDERR
        print STDERR
            "[Error][$Param{Module}] $Self->{CustomPrefix} Priority: '$Param{Priority}' not defined! Message: $Param{Message}\n";

        # and of course to logfile
        print $FH
            "[Error][$Param{Module}] $Self->{CustomPrefix} Priority: '$Param{Priority}' not defined! Message: $Param{Message}\n";

    # close file handle
    close $FH;
    return 1;


Log Module Configuration Example

To activate our custom logging module, the administrator can either set the existing configuration item LogModule manually to Kernel::System::Log::CustomFile. To realize this automatically, you can provide an XML configuration file which overrides the default setting.

<ConfigItem Name="LogModule" Required="1" Valid="1">
    <Description Translatable="1">Set Kernel::System::Log::CustomFile as default logging backend.</Description>
        <Option Location="Kernel/System/Log/*.pm" SelectedID="Kernel::System::Log::CustomFile"></Option>

Log Module Use Case Example

Useful logging back ends could be logging to a web service or to encrypted files.


Kernel::System::Log has other methods than Log() which cannot be reimplemented, for example code for working with shared memory segments and log data caching.