# MQTT

The **MQTT** input plugin, allows to retrieve messages/data from MQTT control packets over a TCP connection. The incoming data to receive *must* be a JSON map.

## Configuration Parameters

The plugin supports the following configuration parameters:

| Key          | Description                                                                                                                         | Default   |
| ------------ | ----------------------------------------------------------------------------------------------------------------------------------- | --------- |
| Listen       | Listener network interface.                                                                                                         | `0.0.0.0` |
| Port         | TCP port where listening for connections.                                                                                           | `1883`    |
| Payload\_Key | Specify the key where the payload key/value will be preserved.                                                                      | *none*    |
| Threaded     | Indicates whether to run this input in its own [thread](https://docs.fluentbit.io/manual/3.1/administration/multithreading#inputs). | `false`   |

## Getting Started

In order to start listening for MQTT messages, you can run the plugin from the command line or through the configuration file:

### Command Line

Since the **MQTT** input plugin let Fluent Bit behave as a server, we need to dispatch some messages using some MQTT client, in the following example *mosquitto* tool is being used for the purpose:

```bash
$ fluent-bit -i mqtt -t data -o stdout -m '*'
Fluent Bit v1.x.x
* 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

[2016/05/20 14:22:52] [ info] starting engine
[0] data: [1463775773, {"topic"=>"some/topic", "key1"=>123, "key2"=>456}]
```

The following command line will send a message to the **MQTT** input plugin:

```bash
$ mosquitto_pub  -m '{"key1": 123, "key2": 456}' -t some/topic
```

### Configuration File

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

```python
[INPUT]
    Name   mqtt
    Tag    data
    Listen 0.0.0.0
    Port   1883

[OUTPUT]
    Name   stdout
    Match  *
```