WebSocket
The websocket output plugin allows to flush your records into a WebSocket endpoint. For now the functionality is pretty basic and it issues a HTTP GET request to do the handshake, and then use TCP connections to send the data records in either JSON or MessagePack (or JSON) format.
Key | Description | default |
Host | IP address or hostname of the target WebScoket Server | 127.0.0.1 |
Port | TCP port of the target WebScoket Server | 80 |
URI | Specify an optional HTTP URI for the target websocket server, e.g: /something | / |
Format | Specify the data format to be used in the HTTP request body, by default it uses msgpack. Other supported formats are json, json_stream and json_lines and gelf. | msgpack |
json_date_key | Specify the name of the date field in output | date |
json_date_format | Specify the format of the date. Supported formats are double and iso8601 (eg: 2018-05-30T09:39:52.000681Z) | double |
idle_interval | The interval that websocket output plugin would keep to decide if it is OK to reconnect to Websocket Server | 20 |
In order to insert records into a HTTP server, you can run the plugin from the command line or through the configuration file:
The websocket plugin, can read the parameters from the command line in two ways, through the -p argument (property) or setting them directly through the service URI. The URI format is the following:
http://host:port/something
Using the format specified, you could start Fluent Bit through:
$ fluent-bit -i cpu -t cpu -o websocket://192.168.2.3:80/something -m '*'
In your main configuration file, append the following Input & Output sections:
[INPUT]Name cpuTag cpu​[OUTPUT]Name websocketMatch *Host 192.168.2.3Port 80URI /somethingFormat jsonIdle_interval 21
Suggested configuration for Idle Interval is 20. Websocket plugin is working with tcp keepalive mode, please refer to networking section for details.
By default, if there is no traffic for about 30 seconds, fluent-bit would abort the tcp connection. As a result, if websocket would like to send data to the same server again, it has to reconnect. This parameter is to help to determine if websocket need to reconnect or not.
[INPUT]Name tcpListen 0.0.0.0Port 5170Format json[OUTPUT]Name websocketMatch *Host 127.0.0.1Port 9000URI /Format jsonIdle_interval 21
Once Fluent Bit is running, you can send some messages using the netcat:
$ echo '{"key 1": 123456789, "key 2": "abcdefg"}' | nc 127.0.0.1 5170; sleep 35; echo '{"key 1": 123456789, "key 2": "abcdefg"}' | nc 127.0.0.1 5170
In Fluent Bit we should see the following output:
bin/fluent-bit -c ../conf/out_ws.confFluent Bit v1.5.0* Copyright (C) 2019-2020 The Fluent Bit Authors* Copyright (C) 2015-2018 Treasure Data* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd* https://fluentbit.io​[2020/07/07 03:39:31] [ info] [storage] version=1.0.4, initializing...[2020/07/07 03:39:31] [ info] [storage] in-memory[2020/07/07 03:39:31] [ info] [storage] normal synchronization mode, checksum disabled, max_chunks_up=128[2020/07/07 03:39:31] [ info] [engine] started (pid=12734)[2020/07/07 03:39:31] [ info] [input:tcp:tcp.0] listening on 0.0.0.0:5170[2020/07/07 03:39:31] [ info] [out_ws] we have following parameter /, 127.0.0.1, 9000, 22[2020/07/07 03:39:31] [ info] [sp] stream processor started[2020/07/07 03:39:36] [ info] [out_ws] handshake for ws[2020/07/07 03:40:11] [ warn] [engine] failed to flush chunk '12734-1594107609.72852130.flb', retry in 6 seconds: task_id=0, input=tcp.0 > output=websocket.0[2020/07/07 03:40:17] [ info] [out_ws] handshake for ws[2020/07/07 03:40:17] [ info] [engine] flush chunk '12734-1594107609.72852130.flb' succeeded at retry 1: task_id=1, input=tcp.0 > output=websocket.0
From the output of fluent-bit log, we see that once data has been ingested into fluent bit, plugin would perform handshake. After a while, no data or traffic is undergoing, tcp connection has been abort. And then another piece of data arrived, a try fro websocket plugin has been triggered, following with another handshake and data flush.
