Merge pull request #418 from influxdata/flux/mqtt-package

Flux MQTT package

content/v2.0/reference/flux/functions/mqtt/_index.md

@@ -0,0 +1,23 @@
+---
+title: Flux MQTT package
+list_title: MQTT package
+description: >
+  The Flux MQTT package provides functions for working with MQTT protocol.
+  Import the `mqtt` package.
+menu:
+  v2_0_ref:
+    name: MQTT
+    parent: Flux packages and functions
+weight: 202
+v2.0/tags: [functions, mqtt, package]
+draft: true
+---
+
+MQTT Flux functions provide tools for working with Message Queuing Telemetry Transport (MQTT) protocol.
+Import the `mqtt` package:
+
+```js
+import "mqtt"
+```
+
+{{< children type="functions" show="pages" >}}

content/v2.0/reference/flux/functions/mqtt/to.md

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+---
+title: mqtt.to() function
+description: >
+  The `mqtt.to()` function outputs data to an MQTT broker using MQTT protocol.
+menu:
+  v2_0_ref:
+    name: mqtt.to
+    parent: MQTT
+weight: 202
+draft: true
+---
+
+The `mqtt.to()` function outputs data to an MQTT broker using MQTT protocol.
+
+_**Function type:** Output_
+
+```js
+import "mqtt"
+
+mqtt.to(
+  broker: "tcp://localhost:8883",
+  topic: "example-topic",
+  message: "Example message",
+  qos: 0,
+  clientid: "flux-mqtt",
+  username: "username",
+  password: "password",
+  name: "name-example",
+  timeout: 1s,
+  timeColumn: "_time",
+  tagColumns: ["tag1", "tag2"],
+  valueColumns: ["_value"]
+)
+```
+
+## Parameters
+
+### broker
+The MQTT broker connection string.
+
+_**Data type: String**_
+
+### topic
+The MQTT topic to send data to.
+
+_**Data type: String**_
+
+### message
+The message or payload to send to the MQTT broker.
+The default payload is an output table.
+If there are multiple output tables, it sends each table as a separate MQTT message.
+
+{{% note %}}
+When you specify a message, the function sends the message string only (no output table).
+{{% /note %}}
+
+_**Data type: String**_
+
+### qos
+The [MQTT Quality of Service (QoS)](https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901103) level.
+Values range from `[0-2]`.
+Default is `0`.
+
+_**Data type: Integer**_
+
+### clientid
+The MQTT client ID.
+
+_**Data type: String**_
+
+### username
+The username to send to the MQTT broker.
+Username is only required if the broker requires authentication.
+If you provide a username, you must provide a [password](#password).
+
+_**Data type: String**_
+
+### password
+The password to send to the MQTT broker.
+Password is only required if the broker requires authentication.
+If you provide a password, you must provide a [username](#username).
+
+_**Data type: String**_
+
+### name
+_(Optional)_ The name for the MQTT message.
+
+_**Data type: String**_
+
+### timeout
+The MQTT connection timeout.
+Default is `1s`.
+
+_**Data type: Duration**_
+
+### timeColumn
+The column to use as time values in the output line protocol.
+Default is `"_time"`.  
+
+_**Data type: String**_
+
+### tagColumns
+The columns to use as tag sets in the output line protocol.
+Default is `[]`.  
+
+_**Data type: Array of strings**_
+
+### valueColumns
+The columns to use as field values in the output line protocol.
+Default is `["_value"]`.
+
+_**Data type: Array of strings**_
+
+## Examples
+
+### Send data to an MQTT endpoint
+```js
+import "mqtt"
+
+from(bucket: "example-bucket")
+  |> range(start: -5m)
+  |> filter(fn: (r) => r._measurement == "airSensor")
+  |> mqtt.to(
+    broker: "tcp://localhost:8883",
+    topic: "air-sensors",
+    clientid: "sensor-12a4",
+    tagColumns: ["sensorID"],
+    valueColumns: ["_value"]
+  )
+```