# MQTT source 

Kuiper provides built-in support for MQTT source stream, which can subscribe the message from MQTT broker and feed into the Kuiper processing pipeline.  The configuration file of MQTT source is at ``$kuiper/etc/mqtt_source.yaml``. Below is the file format.

```yaml
#Global MQTT configurations
default:
  qos: 1
  sharedSubscription: true
  servers: [tcp://127.0.0.1:1883]
  #username: user1
  #password: password
  #certificationPath: /var/kuiper/xyz-certificate.pem
  #privateKeyPath: /var/kuiper/xyz-private.pem.key


#Override the global configurations
demo_conf: #Conf_key
  qos: 0
  servers: [tcp://10.211.55.6:1883, tcp://127.0.0.1]

```

## Global MQTT configurations

Use can specify the global MQTT settings here. The configuration items specified in ``default`` section will be taken as default settings for all MQTT connections. 

### qos

The default subscription QoS level.

### sharedSubscription

Whether use the shared subscription mode or not. If using the shared subscription mode, then there are multiple Kuiper process can be load balanced.

### servers

The server list for MQTT message broker. Currently, only ``ONE`` server can be specified.

### username

The username for MQTT connection. The configuration will not be used if ``certificationPath`` or ``privateKeyPath`` is specified.

### password

The password for MQTT connection. The configuration will not be used if ``certificationPath`` or ``privateKeyPath`` is specified.

### certificationPath

The location of certification path. It can be an absolute path, or a relative path. If it is an relative path, then the base path is where you excuting the ``server`` command. For example, if you run ``bin/server`` from ``/var/kuiper``, then the base path is ``/var/kuiper``; If you run ``./server`` from ``/var/kuiper/bin``, then the base path is ``/var/kuiper/bin``.  Such as  ``d3807d9fa5-certificate.pem``.

### privateKeyPath

The location of private key path. It can be an absolute path, or a relative path.  For more detailed information, please refer to ``certificationPath``. Such as ``d3807d9fa5-private.pem.key``.

## Override the default settings

If you have a specific connection that need to overwrite the default settings, you can create a customized section. In the previous sample, we create a specific setting named with ``demo``.  Then you can specify the configuration with option ``CONF_KEY`` when creating the stream definition (see [stream specs](../../sqls/streams.md) for more info).

**Sample**

```
demo (
		...
	) WITH (datasource="test/", FORMAT="JSON", KEY="USERID", CONF_KEY="demo");
```

The configuration keys used for these specific settings are the same as in ``default`` settings, any values specified in specific settings will overwrite the values in ``default`` section.