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Parse-Syslog-Line-6.2
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NAME

Parse::Syslog::Line - Simple syslog line parser

VERSION

version 6.2

SYNOPSIS

I wanted a very simple log parser for network based syslog input. Nothing existed that simply took a line and returned a hash ref all parsed out.

use Parse::Syslog::Line qw(parse_syslog_line);

$Parse::Syslog::Line::AutoDetectJSON = 1;
$Parse::Syslog::Line::AutoDetectKeyValues = 1;

my $href = parse_syslog_line( $msg );
#
# $href = {
#       preamble        => '13',
#       priority        => 'notice',
#       priority_int    => 5,
#       facility        => 'user',
#       facility_int    => 8,
#       date            => 'YYYY-MM-DD',
#       time            => 'HH::MM:SS',
#       epoch           => 1361095933,
#       datetime_local  => ISO 8601 datetime, in local timezone (potentially buggy)
#       datetime_str    => ISO 8601 datetime, in message timezone
#       datetime_utc    => ISO 8601 datetime, in UTC
#       datetime_raw    => 'Feb 17 11:12:13'
#       host_raw        => 'hostname',  # Hostname as it appeared in the message
#       host            => 'hostname',  # Hostname without domain
#       domain          => 'blah.com',  # if provided
#       program_raw     => 'sshd(blah)[pid]',
#       program_name    => 'sshd',
#       program_sub     => 'pam_unix',
#       program_pid     => 20345,
#       content         => 'the rest of the message'
#       message         => 'program[pid]: the rest of the message',
#       message_raw     => 'The message as it was passed',
#       ntp             => 'ok',        # Only set for Cisco messages
#       version         => 1,
#       SDATA           => { ... },     # RFC Structured data, decoded JSON, or K/V Pairs in the message
# };
...

EXPORT

Exported by default: parse_syslog_line( $one_line_of_syslog_message );

Optional Exports: :preamble preamble_priority preamble_facility

:constants
     %LOG_FACILITY
     %LOG_PRIORITY

:with_timezones
     set_syslog_timezone
     get_syslog_timezone
     use_utc_syslog

VARIABLES

ExtractProgram

If this variable is set to 1 (the default), parse_syslog_line() will try it's best to extract a "program" field from the input. This is the most expensive set of regex in the module, so if you don't need that pre-parsed, you can speed the module up significantly by setting this variable.

Vendors who do proprietary non-sense with their syslog formats are to blame for this setting.

Usage:

$Parse::Syslog::Line::ExtractProgram = 0;

DateParsing

If this variable is set to 0 raw date will not be parsed further into components (datetime_str date time epoch). Default is 1 (parsing enabled).

Usage:

$Parse::Syslog::Line::DateParsing = 0;

TimeMomentFormatString

This defaults to "%FT%T%f%z". See "EXAMPLE FORMAT STRINGS" in Time::Moment for syntax and usage.

EpochCreate

If this variable is set to 1, the default, the number of seconds from UNIX epoch will be returned in the $m->{epoch} field. Setting this to false will only delete the epoch before returning the hash reference.

FmtDate

You can pass your own formatter/parser here. Given a raw datetime string it should output a list containing date, time, epoch, datetime_str, in your wanted format.

use Parse::Syslog::Line;

local $Parse::Syslog::Line::FmtDate = sub {
    my ($raw_datestr) = @_;
    my @elements = (
        #date
        #time
        #epoch
        #datetime_str
    );
    return @elements;
};

NOTE: No further date processing will be done, you're on your own here.

AutoDetectJSON

Default is false. If true, we'll autodetect the presence of JSON in the syslog message and use JSON::MaybeXS to decode it. The detection/decoding is simple. If a '{' is detected, everything until the end of the message is assumed to be JSON. The decoded JSON will be added to the SDATA field.

$Parse::Syslog::Line::AutoDetectJSON = 1;

AutoDetectKeyValues

Default is false. If true, we'll autodetect the presence of Splunk style key/value pairds in the message stream. That format is k1=v1, k2=v2. Resulting K/V pairs will be added to the SDATA field.

$Parse::Syslog::Line::AutoDetectKeyValues = 1;

RFC5424StructuredData

Default is true. When enabled, this will extract the RFC standard structured data from the message content. That content will be stripped from the message content field.

Some examples:

# Input
[foo x=1] some words [bar x=2]

# To (YAML for brevity)
---
SDATA:
  bar:
    x: 2
  foo:
    x: 1
content: some words

# Input
[x=1] some words

# To (YAML for brevity)
---
SDATA:
  x: 1
content: some words

To disable:

$Parse::Syslog::Line::RFC5424StructuredData = 0;

RFC5424StructuredDataStrict

Require the format:

[namespace@id property="value"][namespace@id property="value"]

Defaults to 0, set to 1 to only parse the RFC5424 formatted structured data.

PruneRaw

This variable defaults to 0, set to 1 to delete all keys in the return hash ending in "_raw"

Usage:

$Parse::Syslog::Line::PruneRaw = 1;

PruneEmpty

This variable defaults to 0, set to 1 to delete all keys in the return hash which are undefined.

Usage:

$Parse::Syslog::Line::PruneEmpty = 1;

PruneFields

This should be an array of fields you'd like to be removed from the hash reference.

Usage:

@Parse::Syslog::Line::PruneFields = qw(facility_int priority_int);

FUNCTIONS

parse_syslog_line

Returns a hash reference of syslog message parsed data.

NOTE: Date/time parsing is hard. This module has been optimized to balance common sense and processing speed. Care is taken to ensure that any data input into the system isn't lost, but with the varieties of vendor and admin crafted date formats, we don't always get it right. Feel free to override date processing using by setting the $FmtDate variable or completely disable it with $DateParsing set to 0.

Dates and Version 6+

As of version 6.0 and later, the date parsing is handled by Time::Moment. Ideally, I would use Date for performance reasons, but it requires some heavy XS toolkits to build which don't work on my MacBookPro out of the box. This made the decision to use Time::Moment kinda automatic. If you are seriously concerned with performance, enough to figure out how to package and run Date successfully, you can use the $FmtDate parameter to inject your own date processing logic.

Time::Moment's API and known limitations informed updates to the API and output of dates in this module. It is drastic enough a shift to warrant a major version bump.

"The Effect of Daylight Saving Time" in Time::Moment explains that to properly convert times during DST transitions, things get messy. This caused issues in testing and warrants words of caution here, ALWAYS use datetime_utc or epoch fields for datetime portability.

The changes to the API and fields returned are as follows:

Fields Returned

set_syslog_timezone($timezone_name)

Sets a timezone $timezone_name for parsed messages. This timezone will be used to calculate offset from UTC if a timezone designation is not present in the message being parsed. This timezone will also serve as the source timezone for the datetime_local field.

get_syslog_timezone()

Returns the name of the timezone currently set by set_syslog_timezone.

use_utc_syslog()

A convenient function which sets the syslog timezone to UTC.

parse_syslog_lines

Returns a list of hashes of the lines interpretted.

When passed one or more line of text, attempts to parse that text as syslog data. This function varies from parse_syslog_line in that it handles multi-line messages. The caveat to this, is after the last iteration of the loop, you to call the function by itself to get the last message.

use strict;
use warnings;
use DDP;
use Parse::Syslog::Line qw(parse_syslog_lines);

while(<>) {
    foreach my $log ( parse_syslog_lines($_) ) {
        p($log);
    }
}
p($_) for parse_syslog_lines();

This function holds a parsing buffer which it flushes any time it encounters a line in the stream that starts with non-whitespace. Any lines beginning with whitespace will be assumed to be a continuation of the previous line.

It is not exported by default.

psl_enable_sdata

Call this to turn on all the Structured Data Parsing Options

preamble_priority

Takes the Integer portion of the syslog messsage and returns a hash reference as such:

$prioRef = {
    'preamble'  => 13
    'as_text'   => 'notice',
    'as_int'    => 5,
};

preamble_facility

Takes the Integer portion of the syslog messsage and returns a hash reference as such:

$facRef = {
    'preamble'  => 13
    'as_text'   => 'user',
    'as_int'    => 8,
};

ENVIRONMENT VARIABLES

There are environment variables that affect how we operate. They are not options as they are not intended to be used by our users. Use at your own risk.

PARSE_SYSLOG_LINE_DEBUG

Outputs debugging information about the parser, not really intended for end-users.

PARSE_SYSLOG_LINE_QUIET

Disables warnings in the parse_syslog_line() function

TEST_ACTIVE / TEST2_ACTIVE

Disables warnings in the parse_syslog_line() function

DEVELOPMENT

This module is developed with Dist::Zilla. To build from the repository, use Dist::Zilla:

dzil authordeps --missing |cpanm
dzil listdeps --missing |cpanm
dzil build
dzil test

AUTHOR

Brad Lhotsky brad@divisionbyzero.net

COPYRIGHT AND LICENSE

This software is Copyright (c) 2017 by Brad Lhotsky.

This is free software, licensed under:

The (three-clause) BSD License

CONTRIBUTORS

SUPPORT

Websites

The following websites have more information about this module, and may be of help to you. As always, in addition to those websites please use your favorite search engine to discover more resources.

Bugs / Feature Requests

This module uses the GitHub Issue Tracker: https://github.com/reyjrar/Parse-Syslog-Line/issues

Source Code

This module's source code is available by visiting: https://github.com/reyjrar/Parse-Syslog-Line