mongo

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

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

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 not 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

For more details, see Plugin Management.

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
<inject>
# key name of timestamp
time_key time
</inject>
<buffer>
# flush
flush_interval 10s
</buffer>
</match>

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

Please see the Config File article for the basic structure and syntax of the configuration file. For <buffer> section, please check Buffer section cofiguration.

Parameters

type

The value must be mongo.

host

type

default

version

string

'localhost'

1.0.0

The MongoDB hostname.

port (required)

type

default

version

integer

27017

1.0.0

The MongoDB port.

database

type

default

version

string

required parameter

1.0.0

The database name.

collection (required, if not tag_mapped)

type

default

version

string

'untagged' or required parameter if not tag_mapped

1.0.0

The collection name.

capped

type

default

version

string

optional

1.0.0

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

capped_size

type

default

version

size

optional

1.0.0

Sets the capped collection size.

user

type

default

version

string

nil

1.0.0

The username to use for authentication.

password

type

default

version

string

nil

1.0.0

The password to use for authentication.

time_key

type

default

version

string

time

1.0.0

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

tag_mapped

type

default

version

bool

false

1.0.0

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.

Common Output / Buffer parameters

For common output / buffer parameters, please check the following articles.

Further Reading

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.