Configuring Parser

Parsers are an important component of Fluent Bit, with them you can take any unstructured log entry and give them a structure that makes easier it processing and further filtering.

The parser engine is fully configurable and can process log entries based in two types of format:

• JSON Maps

• Regular Expressions (named capture)

By default, Fluent Bit provides a set of pre-configured parsers that can be used for different use cases such as logs from:

• Apache

• Nginx

• Docker

• Syslog rfc5424

• Syslog rfc3164

Parsers are defined in one or multiple configuration files that are loaded at start time, either from the command line or through the main Fluent Bit configuration file.

Note: If you are using Regular Expressions note that Fluent Bit uses Ruby based regular expressions and we encourage to use Rubular web site as an online editor to test them.

Configuration Parameters

Multiple parsers can be defined and each section has it own properties. The following table describes the available options for each parser definition:

Key	Description
Name	Set an unique name for the parser in question.
Format	Specify the format of the parser, the available options here are: json, regex, ltsv or logfmt.
Regex	If format is regex, this option must be set specifying the Ruby Regular Expression that will be used to parse and compose the structured message.
Time_Key	If the log entry provides a field with a timestamp, this option specifies the name of that field.
Time_Format	Specify the format of the time field so it can be recognized and analyzed properly. Fluent Bit uses strptime(3) to parse time. See the strptime documentation for available modifiers. The %L field descriptor is supported for fractional seconds.
Time_Offset	Specify a fixed UTC time offset (e.g. -0600, +0200, etc.) for local dates.
Time_Keep	By default when a time key is recognized and parsed, the parser will drop the original time field. Enabling this option will make the parser to keep the original time field and its value in the log entry.
Time_System_Timezone	If there is no timezone (%z) specified in the given Time_Format, enabling this option will make the parser detect and use the system's configured timezone. The configured timezone is detected from the TZ environment variable.
Types	Specify the data type of parsed field. The syntax is types <field_name_1>:<type_name_1> <field_name_2>:<type_name_2> .... The supported types are string(default), integer, bool, float, hex. The option is supported by ltsv, logfmt and regex.
Decode_Field	Decode a field value, the only decoder available is json. The syntax is: Decode_Field json <field_name>.
Skip_Empty_Values	Specify a boolean which determines if the parser should skip empty values. The default is true.
Time_Strict	The default value (true) tells the parser to be strict with the expected time format. With this option set to false, the parser will be permissive with the format of the time. This is useful when the format expects time fraction but the time to be parsed doesn't include it.

Parsers Configuration File

All parsers must be defined in a parsers.conf file, not in the Fluent Bit global configuration file. The parsers file expose all parsers available that can be used by the Input plugins that are aware of this feature. A parsers file can have multiple entries like this:

[PARSER]
    Name        docker
    Format      json
    Time_Key    time
    Time_Format %Y-%m-%dT%H:%M:%S.%L
    Time_Keep   On

[PARSER]
    Name        syslog-rfc5424
    Format      regex
    Regex       ^\<(?<pri>[0-9]{1,5})\>1 (?<time>[^ ]+) (?<host>[^ ]+) (?<ident>[^ ]+) (?<pid>[-0-9]+) (?<msgid>[^ ]+) (?<extradata>(\[(.*)\]|-)) (?<message>.+)$
    Time_Key    time
    Time_Format %Y-%m-%dT%H:%M:%S.%L
    Time_Keep   On
    Types pid:integer

For more information about the parsers available, please refer to the default parsers file distributed with Fluent Bit source code:

https://github.com/fluent/fluent-bit/blob/master/conf/parsers.conf

Time Resolution and Fractional Seconds

Time resolution and its format supported are handled by using the strftime(3) libc system function.

In addition, we extended our time resolution to support fractional seconds like 2017-05-17T15:44:31**.187512963**Z. Since Fluent Bit v0.12 we have full support for nanoseconds resolution, the %L format option for Time_Format is provided as a way to indicate that content must be interpreted as fractional seconds.

Note: The option %L is only valid when used after seconds (%S) or seconds since the Epoch (%s), e.g: %S.%L or %s.%L

Supported Timezone Abbreviations

The current supported time zone labels of 3-4 letter abbreviated strings:

UTC/GMT and Zulu

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
GMT	+00:00	0	0	Greenwich Mean Time
UTC	+00:00	0	0	Coordinated Universal Time
Z	+00:00	0	0	Zulu Time (UTC)
UT	+00:00	0	0	Universal Time

North American Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
EST	-05:00	-18000	0	Eastern Standard Time
EDT	-04:00	-14400	1	Eastern Daylight Time
CST	-06:00	-21600	0	Central Standard Time (North America)
CDT	-05:00	-18000	1	Central Daylight Time (North America)
MST	-07:00	-25200	0	Mountain Standard Time
MDT	-06:00	-21600	1	Mountain Daylight Time
PST	-08:00	-28800	0	Pacific Standard Time
PDT	-07:00	-25200	1	Pacific Daylight Time
AKST	-09:00	-32400	0	Alaska Standard Time
AKDT	-08:00	-28800	1	Alaska Daylight Time
HST	-10:00	-36000	0	Hawaii Standard Time
HADT	-09:00	-32400	1	Hawaii-Aleutian Daylight Time (rarely used for Hawaii)
AST	-04:00	-14400	0	Atlantic Standard Time (e.g., Canada, Caribbean)
ADT	-03:00	-10800	1	Atlantic Daylight Time
NST	-03:30	-12600	0	Newfoundland Standard Time
NDT	-02:30	-9000	1	Newfoundland Daylight Time

European Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
WET	+00:00	0	0	Western European Time
WEST	+01:00	3600	1	Western European Summer Time
CET	+01:00	3600	0	Central European Time
CEST	+02:00	7200	1	Central European Summer Time
EET	+02:00	7200	0	Eastern European Time
EEST	+03:00	10800	1	Eastern European Summer Time
MSK	+03:00	10800	0	Moscow Standard Time

South American Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
ART	-03:00	-10800	0	Argentina Time
BRT	-03:00	-10800	0	Brazil Time (main population areas, can vary by region/DST)
BRST	-02:00	-7200	1	Brazil Summer Time (historical, not currently observed by all)
CLT	-04:00	-14400	0	Chile Standard Time
CLST	-03:00	-10800	1	Chile Summer Time

Australasian / Oceanian Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
AEST	+10:00	36000	0	Australian Eastern Standard Time
AEDT	+11:00	39600	1	Australian Eastern Daylight Time
ACST	+09:30	34200	0	Australian Central Standard Time
ACDT	+10:30	37800	1	Australian Central Daylight Time
AWST	+08:00	28800	0	Australian Western Standard Time
NZST	+12:00	43200	0	New Zealand Standard Time
NZDT	+13:00	46800	1	New Zealand Daylight Time

Asian Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
JST	+09:00	32400	0	Japan Standard Time
KST	+09:00	32400	0	Korea Standard Time
SGT	+08:00	28800	0	Singapore Time
IST	+05:30	19800	0	India Standard Time
GST	+04:00	14400	0	Gulf Standard Time (e.g., UAE, Oman)
ICT	+07:00	25200	0	Indochina Time (Thailand, Vietnam, Laos, Cambodia)
WIB	+07:00	25200	0	Western Indonesian Time
WITA	+08:00	28800	0	Central Indonesian Time
WIT	+09:00	32400	0	Eastern Indonesian Time
MYT	+08:00	28800	0	Malaysia Time
BDT	+06:00	21600	0	Bangladesh Standard Time
NPT	+05:45	20700	0	Nepal Time

African Timezones

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
WAT	+01:00	3600	0	West Africa Time
CAT	+02:00	7200	0	Central Africa Time
EAT	+03:00	10800	0	East Africa Time
SAST	+02:00	7200	0	South Africa Standard Time

Military Timezones

These are single-letter UTC offset designators. 'J' (Juliett) represents local time and is not included. 'Z' (Zulu) is UTC and listed above.

Abbreviation	UTC Offset (HH:MM)	Offset (Seconds)	Is DST	Description
A	+01:00	3600	0	Alpha Time Zone
B	+02:00	7200	0	Bravo Time Zone
C	+03:00	10800	0	Charlie Time Zone
D	+04:00	14400	0	Delta Time Zone
E	+05:00	18000	0	Echo Time Zone
F	+06:00	21600	0	Foxtrot Time Zone
G	+07:00	25200	0	Golf Time Zone
H	+08:00	28800	0	Hotel Time Zone
I	+09:00	32400	0	India Time Zone (Military, not India Standard Time)
K	+10:00	36000	0	Kilo Time Zone
L	+11:00	39600	0	Lima Time Zone
M	+12:00	43200	0	Mike Time Zone
N	-01:00	-3600	0	November Time Zone
O	-02:00	-7200	0	Oscar Time Zone
P	-03:00	-10800	0	Papa Time Zone
Q	-04:00	-14400	0	Quebec Time Zone
R	-05:00	-18000	0	Romeo Time Zone
S	-06:00	-21600	0	Sierra Time Zone
T	-07:00	-25200	0	Tango Time Zone
U	-08:00	-28800	0	Uniform Time Zone
V	-09:00	-32400	0	Victor Time Zone
W	-10:00	-36000	0	Whiskey Time Zone
X	-11:00	-43200	0	X-ray Time Zone
Y	-12:00	-46800	0	Yankee Time Zone