Forward

Forward is the protocol used by Fluent Bit and Fluentd to route messages between peers. This plugin implements the input service to listen for Forward messages.

Configuration parameters

The plugin supports the following configuration parameters:

Key	Description	Default
Listen	Listener network interface.	0.0.0.0
Port	TCP port to listen for incoming connections.	24224
Unix_Path	Specify the path to Unix socket to receive a Forward message. If set, Listen and Port are ignored.	none
Unix_Perm	Set the permission of the Unix socket file. If Unix_Path isn't set, this parameter is ignored.	none
Buffer_Max_Size	Specify the maximum buffer memory size used to receive a Forward message. The value must be according to the Unit Size specification.	6144000
Buffer_Chunk_Size	By default the buffer to store the incoming Forward messages, don't allocate the maximum memory allowed, instead it allocate memory when it's required. The rounds of allocations are set by Buffer_Chunk_Size. The value must be according to the Unit Size specification.	1024000
Tag_Prefix	Prefix incoming tag with the defined value.	none
Tag	Override the tag of the forwarded events with the defined value.	none
Shared_Key	Shared key for secure forward authentication.	none
Empty_Shared_Key	Use this option to connect to Fluentd with a zero-length shared key.	false
Self_Hostname	Hostname for secure forward authentication.	none
Security.Users	Specify the username and password pairs for secure forward authentication.
Threaded	Indicates whether to run this input in its own thread.	false

Get started

To receive Forward messages, you can run the plugin from the command line or through the configuration file as shown in the following examples.

Command line

From the command line you can let Fluent Bit listen for Forward messages with the following options:

fluent-bit -i forward -o stdout

By default, the service listens on all interfaces (0.0.0.0) through TCP port 24224. You can change this by passing parameters to the command:

fluent-bit -i forward -p listen="192.168.3.2" -p port=9090 -o stdout

In the example, the Forward messages arrive only through network interface 192.168.3.2 address and TCP Port 9090.

Configuration file

In your main configuration file append the following Input and Output sections:

fluent-bit.conf

[INPUT]
    Name              forward
    Listen            0.0.0.0
    Port              24224
    Buffer_Chunk_Size 1M
    Buffer_Max_Size   6M

[OUTPUT]
    Name   stdout
    Match  *

fluent-bit.yaml

pipeline:
    inputs:
        - name: forward
          listen: 0.0.0.0
          port: 24224
          buffer_chunk_size: 1M
          buffer_max_size: 6M
    outputs:
        - name: stdout
          match: '*'

Fluent Bit and Secure Forward Setup

In Fluent Bit v3 or later, in_forward can handle secure forward protocol.

For using user-password authentication, specify security.users at least an one-pair. For using shared key, specify shared_key in both of forward output and forward input.self_hostname isn't able to specify with the same hostname between fluent servers and clients.

fluent-bit-secure-forward.conf

[INPUT]
    Name              forward
    Listen            0.0.0.0
    Port              24224
    Buffer_Chunk_Size 1M
    Buffer_Max_Size   6M
    Security.Users fluentbit changeme
    Shared_Key secret
    Self_Hostname flb.server.local

[OUTPUT]
    Name   stdout
    Match  *

fluent-bit-secure-forward.yaml

pipeline:
    inputs:
        - name: forward
          listen: 0.0.0.0
          port: 24224
          buffer_chunk_size: 1M
          buffer_max_size: 6M
          security.users: fluentbit changeme
          shared_key: secret
          self_hostname: flb.server.local
    outputs:
        - name: stdout
          match: '*'

Testing

After Fluent Bit is running, you can send some messages using the fluent-cat tool, provided by Fluentd:

echo '{"key 1": 123456789, "key 2": "abcdefg"}' | fluent-cat my_tag

When you run the plugin with the following command:

bin/fluent-bit -i forward -o stdout

In Fluent Bit you should see the following output:

Fluent-Bit v0.9.0
Copyright (C) Treasure Data

[2016/10/07 21:49:40] [ info] [engine] started
[2016/10/07 21:49:40] [ info] [in_fw] binding 0.0.0.0:24224
[0] my_tag: [1475898594, {"key 1"=>123456789, "key 2"=>"abcdefg"}]