# MQTT action

The action is used for publish output message into an MQTT server.

Property nameOptionalDescription
serverfalseThe broker address of the MQTT server, such as tcp://127.0.0.1:1883
topicfalseThe MQTT topic, such as analysis/result
clientIdtrueThe client id for MQTT connection. If not specified, an uuid will be used
protocolVersiontrueMQTT protocol version. 3.1 (also refer as MQTT 3) or 3.1.1 (also refer as MQTT 4). If not specified, the default value is 3.1.
qostrueThe QoS for message delivery. Only int type value 0 or 1 or 2.
usernametrueThe username for the connection.
passwordtrueThe password for the connection.
certificationPathtrueThe 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 kuiperd command. For example, if you run bin/kuiperd from /var/kuiper, then the base path is /var/kuiper; If you run ./kuiperd from /var/kuiper/bin, then the base path is /var/kuiper/bin.
privateKeyPathtrueThe private key path. It can be either absolute path, or relative path, which is similar to use of certificationPath.
insecureSkipVerifytrueIf InsecureSkipVerify is true, TLS accepts any certificate presented by the server and any host name in that certificate. In this mode, TLS is susceptible to man-in-the-middle attacks. The default value is false. The configuration item can only be used with TLS connections.
retainedtrueIf retained is true,The broker stores the last retained message and the corresponding QoS for that topic.The default value is false.

Below is sample configuration for connecting to Azure IoT Hub by using SAS authentication.

    {
      "mqtt": {
        "server": "ssl://xyz.azure-devices.net:8883",
        "topic": "devices/demo_001/messages/events/",
        "protocolVersion": "3.1.1",
        "qos": 1,
        "clientId": "demo_001",
        "username": "xyz.azure-devices.net/demo_001/?api-version=2018-06-30",
        "password": "SharedAccessSignature sr=*******************",
        "retained": false
      }
    }
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Below is another sample configuration for connecting to AWS IoT by using certification and privte key auth.

    {
      "mqtt": {
        "server": "ssl://xyz-ats.iot.us-east-1.amazonaws.com:8883",
        "topic": "devices/result",
        "qos": 1,
        "clientId": "demo_001",
        "certificationPath": "keys/d3807d9fa5-certificate.pem",
        "privateKeyPath": "keys/d3807d9fa5-private.pem.key", 
        "insecureSkipVerify": false,
        "retained": false
      }
    }
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