<1> *<source>* directives determine the input sources. The source submits events to the Fluentd routing engine. An event consists of three entities: *tag*, *time* and *record*.
<2> The *tail Input plugin* allows Fluentd to read events from the tail of text files. Its behavior is similar to the tail -F command. xref:doc-dummy_service.adoc#tailmongo[see image: type tai]
<3> The *path(s) to read*. Multiple paths can be specified, separated by comma ','. '*' format can be included to add/remove the watch file dynamically. At the interval of refresh_interval, Fluentd refreshes the list of watch files.
<4> *pos_file* handles multiple positions in one file so no need to have multiple pos_file parameters per source. Don't share *pos_file* between *tail* configurations. It causes unexpected behavior e.g. corrupt pos_file content.
<5> The *tag* of the event.
<6> Enables the additional inotify-based watcher. *Either of enable_watch_timer or enable_stat_watcher must be true*
<7> Enables the additional watch timer. *Either of enable_watch_timer or enable_stat_watcher must be true*
<8> The *none parser plugin* parses the line as-is with the single field. This format is to defer the parsing/structuring of the data.
<9> *<match>* directives determine the output destinations. The match directive looks for events with matching tags and processes them. The most common use of the match directive is to *output events to other systems*.
<10> Chooses how to pass the events to <store> plugins. *deep* copied events to each store plugin. This mode is useful when you modify the nested field after out_copy, e.g. Docker Swarm/Kubernetes related fields.
<11> Specifies the *storage destinations*. The format is the same as the <match> directive. This section is required at least once.
<12> The *mongo Output plugin* writes records into , the document-oriented database system.
<13> The https://docs.mongodb.com/manual/reference/connection-string/#std-label-connections-standard-connection-string-format[MongoDB connection string^] for URI.
<14> This option enables the *capped collection*. This is always recommended. https://docs.mongodb.com/manual/core/capped-collections/[Capped collections^] are fixed-size collections that support high-throughput operations that insert and retrieve documents based on insertion order. Capped collections work in a way similar to circular buffers: once a collection fills its allocated space, it makes room for new documents by overwriting the oldest documents in the collection.
