Kafka output plugin allows to ingest your records into an Apache Kafka service. This plugin use the official librdkafka C library (built-in dependency)
Configuration Parameters
Key
Description
default
Setting rdkafka.log.connection.close to false and rdkafka.request.required.acks to 1 are examples of recommended settings of librdfkafka properties.
Getting Started
In order to insert records into Apache Kafka, you can run the plugin from the command line or through the configuration file:
Command Line
The kafka plugin can read parameters through the -p argument (property), e.g:
Configuration File
In your main configuration file append the following Input & Output sections:
Avro Support
Fluent-bit comes with support for avro encoding for the out_kafka plugin. Avro support is optional and must be activated at build-time by using a build def with cmake: -DFLB_AVRO_ENCODER=On such as in the following example which activates:
out_kafka with avro encoding
fluent-bit's prometheus
metrics via an embedded http endpoint
debugging support
Kafka Configuration File with Avro Encoding
This is example fluent-bit config tails kubernetes logs, decorates the log lines with kubernetes metadata via the kubernetes filter, and then sends the fully decorated log lines to a kafka broker encoded with a specific avro schema.
Kafka Configuration File with Raw format
This example Fluent Bit configuration file creates example records with the payloadkey and msgkey keys. The msgkey value is used as the Kafka message key, and the payloadkey value as the payload.
builds the test suites
format
Specify data format, options available: json, msgpack, raw.
json
message_key
Optional key to store the message
message_key_field
If set, the value of Message_Key_Field in the record will indicate the message key. If not set nor found in the record, Message_Key will be used (if set).
timestamp_key
Set the key to store the record timestamp
@timestamp
timestamp_format
Specify timestamp format, should be 'double', 'iso8601' (seconds precision) or 'iso8601_ns' (fractional seconds precision)
double
brokers
Single or multiple list of Kafka Brokers, e.g: 192.168.1.3:9092, 192.168.1.4:9092.
topics
Single entry or list of topics separated by comma (,) that Fluent Bit will use to send messages to Kafka. If only one topic is set, that one will be used for all records. Instead if multiple topics exists, the one set in the record by Topic_Key will be used.
fluent-bit
topic_key
If multiple Topics exists, the value of Topic_Key in the record will indicate the topic to use. E.g: if Topic_Key is router and the record is {"key1": 123, "router": "route_2"}, Fluent Bit will use topic route_2. Note that if the value of Topic_Key is not present in Topics, then by default the first topic in the Topics list will indicate the topic to be used.
dynamic_topic
adds unknown topics (found in Topic_Key) to Topics. So in Topics only a default topic needs to be configured
Off
queue_full_retries
Fluent Bit queues data into rdkafka library, if for some reason the underlying library cannot flush the records the queue might fills up blocking new addition of records. The queue_full_retries option set the number of local retries to enqueue the data. The default value is 10 times, the interval between each retry is 1 second. Setting the queue_full_retries value to 0 set's an unlimited number of retries.
[INPUT]
Name tail
Tag kube.*
Alias some-alias
Path /logdir/*.log
DB /dbdir/some.db
Skip_Long_Lines On
Refresh_Interval 10
Parser some-parser
[FILTER]
Name kubernetes
Match kube.*
Kube_URL https://some_kube_api:443
Kube_CA_File /certs/ca.crt
Kube_Token_File /tokens/token
Kube_Tag_Prefix kube.var.log.containers.
Merge_Log On
Merge_Log_Key log_processed
[OUTPUT]
Name kafka
Match *
Brokers 192.168.1.3:9092
Topics test
Schema_str {"name":"avro_logging","type":"record","fields":[{"name":"timestamp","type":"string"},{"name":"stream","type":"string"},{"name":"log","type":"string"},{"name":"kubernetes","type":{"name":"krec","type":"record","fields":[{"name":"pod_name","type":"string"},{"name":"namespace_name","type":"string"},{"name":"pod_id","type":"string"},{"name":"labels","type":{"type":"map","values":"string"}},{"name":"annotations","type":{"type":"map","values":"string"}},{"name":"host","type":"string"},{"name":"container_name","type":"string"},{"name":"docker_id","type":"string"},{"name":"container_hash","type":"string"},{"name":"container_image","type":"string"}]}},{"name":"cluster_name","type":"string"},{"name":"fabric","type":"string"}]}
Schema_id some_schema_id
rdkafka.client.id some_client_id
rdkafka.debug All
rdkafka.enable.ssl.certificate.verification true
rdkafka.ssl.certificate.location /certs/some.cert
rdkafka.ssl.key.location /certs/some.key
rdkafka.ssl.ca.location /certs/some-bundle.crt
rdkafka.security.protocol ssl
rdkafka.request.required.acks 1
rdkafka.log.connection.close false
Format avro
rdkafka.log_level 7
rdkafka.metadata.broker.list 192.168.1.3:9092
[INPUT]
Name example
Tag example.data
Dummy {"payloadkey":"Data to send to kafka", "msgkey": "Key to use in the message"}
[OUTPUT]
Name kafka
Match *
Brokers 192.168.1.3:9092
Topics test
Format raw
Raw_Log_Key payloadkey
Message_Key_Field msgkey