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Data Collection

MongoDB Output Plugin

The out_mongo Buffered Output plugin writes records into MongoDB, the emerging document-oriented database system.

NOTE: If you're using ReplicaSet, please see the out_mongo_replset article instead.

NOTE: This document doesn't describe all parameters. If you want to know full features, check the Further Reading section.

Why Fluentd with MongoDB?

Fluentd enables your apps to insert records to MongoDB asynchronously with batch-insertion, unlike direct insertion of records from your apps. This has the following advantages:

  1. less impact on application performance
  2. higher MongoDB insertion throughput while maintaining JSON record structure

Install

out_mongo is included in td-agent by default. Fluentd gem users will need to install the fluent-plugin-mongo gem using the following command.

$ fluent-gem install fluent-plugin-mongo

Example Configuration

# Single MongoDB
<match mongo.**>
  type mongo
  host fluentd
  port 27017
  database fluentd
  collection test

  # for capped collection
  capped
  capped_size 1024m

  # authentication
  user michael
  password jordan

  # key name of timestamp
  time_key time

  # flush
  flush_interval 10s
</match>

Please see the Store Apache Logs into MongoDB article for real-world use cases.

NOTE: Please see the Config File article for the basic structure and syntax of the configuration file.

Parameters

type (required)

The value must be mongo.

host (required)

The MongoDB hostname.

port (required)

The MongoDB port.

database (required)

The database name.

collection (required, if not tag_mapped)

The collection name.

capped

This option enables capped collection. This is always recommended because MongoDB is not suited to storing large amounts of historical data.

capped_size

Sets the capped collection size.

user

The username to use for authentication.

password

The password to use for authentication.

time_key

The key name of timestamp. (default is "time")

tag_mapped

This option will allow out_mongo to use Fluentd's tag to determine the destination collection. For example, if you generate records with tags 'mongo.foo', the records will be inserted into the foo collection within the fluentd database.

<match mongo.*>
  type mongo
  host fluentd
  port 27017
  database fluentd

  # Set 'tag_mapped' if you want to use tag mapped mode.
  tag_mapped

  # If the tag is "mongo.foo", then the prefix "mongo." is removed.
  # The inserted collection name is "foo".
  remove_tag_prefix mongo.

  # This configuration is used if the tag is not found. The default is 'untagged'.
  collection misc
</match>

This option is useful for flexible log collection.

INCLUDE: _buffer_parameters

INCLUDE: _log_level_params

Further Reading