mongo
The out_mongo
Buffered 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:
less impact on application performance
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.
Example Configuration
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.
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.
This option is useful for flexible log collection.
Buffered Output Parameters
For advanced usage, you can tune Fluentd's internal buffering mechanism with these parameters.
buffer_type
The buffer type is memory
by default (buf_memory) for the ease of testing, however file
(buf_file) buffer type is always recommended for the production deployments. If you use file
buffer type, buffer_path
parameter is required.
buffer_queue_limit, buffer_chunk_limit
The length of the chunk queue and the size of each chunk, respectively. Please see the Buffer Plugin Overview article for the basic buffer structure. The default values are 64 and 8m, respectively. The suffixes "k" (KB), "m" (MB), and "g" (GB) can be used for buffer_chunk_limit.
flush_interval
The interval between data flushes. The default is 60s. The suffixes "s" (seconds), "m" (minutes), and "h" (hours) can be used.
flush_at_shutdown
If set to true, Fluentd waits for the buffer to flush at shutdown. By default, it is set to true for Memory Buffer and false for File Buffer.
retry_wait, max_retry_wait
The initial and maximum intervals between write retries. The default values are 1.0 seconds and unset (no limit). The interval doubles (with +/-12.5% randomness) every retry until max_retry_wait
is reached.
Since td-agent will retry 17 times before giving up by default (see the retry_limit
parameter for details), the sleep interval can be up to approximately 131072 seconds (roughly 36 hours) in the default configurations.
retry_limit, disable_retry_limit
The limit on the number of retries before buffered data is discarded, and an option to disable that limit (if true, the value of retry_limit
is ignored and there is no limit). The default values are 17 and false (not disabled). If the limit is reached, buffered data is discarded and the retry interval is reset to its initial value (retry_wait
).
num_threads
The number of threads to flush the buffer. This option can be used to parallelize writes into the output(s) designated by the output plugin. Increasing the number of threads improves the flush throughput to hide write / network latency. The default is 1.
slow_flush_log_threshold
The threshold for checking chunk flush performance. The default value is 20.0
seconds. Note that parameter type is float
, not time
.
If chunk flush takes longer time than this threshold, fluentd logs warning message like below:
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.
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.
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