The filter_stdout filter plugin prints events to stdout (or logs if launched with daemon mode). This filter plugin is useful for debugging purposes.

Example Configurations

filter_stdout is included in Fluentd's core. No installation required.

<filter pattern>
  @type stdout
</filter>

A sample output is as follows:

2015-05-02 12:12:17 +0900 tag: {"field1":"value1","field2":"value2"}

where the first part shows the output time, the second part shows the tag, and the third part shows the record. The first part shows the **output** time, not the time attribute of message event structure as `out_stdout` does.

Parameters

type (required)

The value must be stdout.

format

The format of the output. The default is stdout.

output_type

This is the option of stdout format. Configure the format of record (third part). Any formatter plugins can be specified. The default is json.

out_file

Output time, tag and json record separated by a delimiter:

time[delimiter]tag[delimiter]record\n

Example:

2014-06-08T23:59:40[TAB]file.server.logs[TAB]{"field1":"value1","field2":"value2"}\n

out_file format has several options to customize the format.

delimiter SPACE   # Optional, SPACE or COMMA. "\t"(TAB) is used by default
output_tag false  # Optional, defaults to true. Output the tag field if true.
output_time true  # Optional, defaults to true. Output the time field if true.

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

json

Output a json record without the time or tag field:

{"field1":"value1","field2":"value2"}\n

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

hash

Output a record as ruby hash without the time or tag field:

{"field1"=>"value1","field2"=>"value2"}\n

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

ltsv

Output the record as LTSV:

field1[label_delimiter]value1[delimiter]field2[label_delimiter]value2\n

ltsv format supports delimiter and label_delimiter options.

format ltsv
delimiter SPACE   # Optional. "\t"(TAB) is used by default
label_delimiter = # Optional. ":" is used by default

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

single_value

Output the value of a single field instead of the whole record. Often used in conjunction with in_tail's format none.

value1\n

single_value format supports the add_newline and message_key options.

add_newline false # Optional, defaults to true. If there is a trailing "\n" already, set it "false"
message_key my_field # Optional, defaults to "message". The value of this field is outputted.

csv

Output the record as CSV/TSV:

"value1"[delimiter]"value2"[delimiter]"value3"\n

csv format supports the delimiter and force_quotes options.

format csv
fields field1,field2,field3
delimiter \t   # Optional. "," is used by default.
force_quotes false # Optional. true is used by default. If false, value won't be framed by quotes.

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

stdout

This format is aimed to be used by stdout plugins.

Output time, tag and formatted record as follows:

time tag: formatted_record\n

Example:

2015-05-02 12:12:17 +0900 tag: {"field1":"value1","field2":"value2"}\n

stdout format has a following option to customize the format of the record part.

output_type format # Optional, defaults to "json". The format of
`formatted_record`. Any formatter plugins can be specified.

For this format, the following common parameters are also supported.

• include_time_key (Boolean, Optional, defaults to false) If

  true, the time field (as specified by the time_key parameter) is

  kept in the record.

• time_key (String, Optional, defaults to "time") The field name

  for the time key.

• time_format (String. Optional) By default, the output format is

  iso8601 (e.g. "2008-02-01T21:41:49"). One can specify their own

  format with this parameter.

• include_tag_key (Boolean. Optional, defaults to false) If

  true, the tag field (as specified by the tag_key parameter) is

  kept in the record.

• tag_key (String, Optional, defaults to "tag") The field name

  for the tag key.

• localtime (Boolean. Optional, defaults to true) If true, use

  local time. Otherwise, UTC is used. This parameter is overwritten by

  the utc parameter.

• timezone (String. Optional) By setting this parameter, one can parse the time value in the specified timezone. The following formats are accepted:

  1. [+-]HH:MM (e.g. "+09:00")

  2. [+-]HHMM (e.g. "+0900")

  3. [+-]HH (e.g. "+09")

  4. Region/Zone (e.g. "Asia/Tokyo")

  5. Region/Zone/Zone (e.g. "America/Argentina/Buenos_Aires")

  The timezone set in this parameter takes precedence over localtime, e.g., if localtime is set to true but timezone is set to +0000, UTC would be used.

log_level option

The log_level option allows the user to set different levels of logging for each plugin. The supported log levels are: fatal, error, warn, info, debug, and trace.

Please see the logging article for further details.

Learn More

• ​Filter Plugin Overview​

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is a open source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.