# WebSocket The *WebSocket* output plugin lets you flush your records into a WebSocket endpoint. It issues an HTTP `GET` request to do the handshake, and then uses TCP connections to send the data records in either JSON or [MessagePack](http://msgpack.org) format. ## Configuration parameters This plugin supports the following parameters: | Key | Description | Default | | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------ | ----------- | | `Host` | IP address or hostname of the target WebSocket Server. | `127.0.0.1` | | `Port` | TCP port of the target WebSocket Server. | `80` | | `URI` | Specify an optional HTTP URI for the target WebSocket server. For example, `/someuri`. | `/` | | `Header` | Add a HTTP header key/value pair. Multiple headers can be set. | *none* | | `Format` | Specify the data format to be used in the HTTP request body. Supported formats: `json`, `json_stream`, `json_lines`, `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: `double`, `epoch`, `epoch_ms`, `iso8601`, `java_sql_timestamp`. | `double` | | `workers` | The number of [workers](https://docs.fluentbit.io/manual/4.1/administration/multithreading#outputs) to perform flush operations for this output. | `0` | ## Get started To insert records into an HTTP server, you can run the plugin from the command line or through the configuration file. ### Command line The WebSocket plugin can read the parameters from the command line through the `-p` argument (property) or by 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: ```shell fluent-bit -i cpu -t cpu -o websocket://192.168.2.3:80/something -m '*' ``` ### Configuration file In your main configuration file, append the following: {% tabs %} {% tab title="fluent-bit.yaml" %} ```yaml pipeline: inputs: - name: cpu tag: cpu outputs: - name: websocket match: '*' host: 192.168.2.3 port: 80 uri: /something format: json ``` {% endtab %} {% tab title="fluent-bit.conf" %} ``` [INPUT] Name cpu Tag cpu [OUTPUT] Name websocket Match * Host 192.168.2.3 Port 80 URI /something Format json ``` {% endtab %} {% endtabs %} For details about how the WebSocket plugin works with TCP keepalive mode, see [networking](https://docs.fluentbit.io/manual/v/master/administration/networking#configuration-options). Because WebSocket is a stateful plugin, it will decide when to send out handshake to server side. For example, when the plugin begins to work or after connection with server has been dropped. In general, the interval to init a new WebSocket handshake would be less than the keepalive interval. With that strategy, it could detect and resume WebSocket connections. ## Tests ### Configuration file example {% tabs %} {% tab title="fluent-bit.yaml" %} ```yaml pipeline: inputs: - name: tcp listen: 0.0.0.0 port: 5170 format: json outputs: - name: websocket match: '*' host: 127.0.0.1 port: 8080 uri: / format: json workers: 4 net.keepalive: on net.keepalive_idle_timeout: 30 ``` {% endtab %} {% tab title="fluent-bit.conf" %} ``` [INPUT] Name tcp Listen 0.0.0.0 Port 5170 Format json [OUTPUT] Name websocket Match * Host 127.0.0.1 Port 8080 URI / Format json workers 4 net.keepalive on net.keepalive_idle_timeout 30 ``` {% endtab %} {% endtabs %} When Fluent Bit is running, you can send some messages using `netcat`: ```shell 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](http://fluentbit.io) you should see the following output: ```shell fluent-bit -c ../conf/out_ws.conf ... [2021/02/05 22:17:09] [ info] [input:tcp:tcp.0] listening on 0.0.0.0:5170 [2021/02/05 22:17:09] [ info] [out_ws] we have following parameter /, 127.0.0.1, 8080, 25 [2021/02/05 22:17:09] [ info] [output:websocket:websocket.0] worker #1 started [2021/02/05 22:17:09] [ info] [output:websocket:websocket.0] worker #0 started [2021/02/05 22:17:09] [ info] [sp] stream processor started [2021/02/05 22:17:09] [ info] [output:websocket:websocket.0] worker #3 started [2021/02/05 22:17:09] [ info] [output:websocket:websocket.0] worker #2 started [2021/02/05 22:17:33] [ info] [out_ws] handshake for ws [2021/02/05 22:18:08] [ warn] [engine] failed to flush chunk '6056-1612534687.673438119.flb', retry in 7 seconds: task_id=0, input=tcp.0 > output=websocket.0 (out_id=0) [2021/02/05 22:18:15] [ info] [out_ws] handshake for ws ^C[2021/02/05 22:18:23] [engine] caught signal (SIGINT) [2021/02/05 22:18:23] [ warn] [engine] service will stop in 5 seconds [2021/02/05 22:18:27] [ info] [engine] service stopped [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #0 stopping... [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #0 stopped [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #1 stopping... [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #1 stopped [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #2 stopping... [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #2 stopped [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #3 stopping... [2021/02/05 22:18:27] [ info] [output:websocket:websocket.0] thread worker #3 stopped [2021/02/05 22:18:27] [ info] [out_ws] flb_ws_conf_destroy ... ``` ### Scenario description From the output of the Fluent Bit log, you can see that when data has been ingested into Fluent Bit, the plugin performs a handshake. If no data or traffic is ongoing, the TCP connection would be aborted. When additional data arrives, a retry for WebSocket plugin triggers, with another handshake and data flush. In another scenario, if the WebSocket server goes down and up in a short time, Fluent Bit would resume the TCP connection immediately. But in that case, the WebSocket output plugin is a malfunction state, and needs to restart Fluent Bit to resume working.