# Republish
<a name="republish-rule-action"></a>

The republish (`republish`) action republishes an MQTT message to another MQTT topic.

## Requirements
<a name="republish-rule-action-requirements"></a>

This rule action has the following requirements:
+ An IAM role that AWS IoT can assume to perform the `iot:Publish` operation. For more information, see [Granting an AWS IoT rule the access it requires](iot-create-role.md).

  In the AWS IoT console, you can choose or create a role to allow AWS IoT to perform this rule action.

## Parameters
<a name="republish-rule-action-parameters"></a>

When you create an AWS IoT rule with this action, you must specify the following information:

`headers`  
MQTT Version 5.0 headers information.  
For more information, see [RepublishAction](https://docs.aws.amazon.com//iot/latest/apireference/API_RepublishAction.html) and [MqttHeaders](https://docs.aws.amazon.com//iot/latest/apireference/API_MqttHeaders.html) in the *AWS API Reference*.

`topic`  
The MQTT topic to which to republish the message.  
To republish to a reserved topic, which begins with `$`, use `$$` instead. For example, to republish to the device shadow topic `$aws/things/MyThing/shadow/update`, specify the topic as `$$aws/things/MyThing/shadow/update`.  
Republishing to [reserved job topics](reserved-topics.md#reserved-topics-job) is not supported.   
AWS IoT Device Defender reserve topics don't support HTTP publish.
Supports [substitution templates](iot-substitution-templates.md): Yes

`qos`  
(Optional) The Quality of Service (QoS) level to use when republishing messages. Valid values: `0`, `1`. The default value is `0`. For more information about MQTT QoS, see [MQTT](mqtt.md).  
Supports [substitution templates](iot-substitution-templates.md): No

`roleArn`  
The IAM role that allows AWS IoT to publish to the MQTT topic. For more information, see [Requirements](#republish-rule-action-requirements).  
Supports [substitution templates](iot-substitution-templates.md): No

## Examples
<a name="republish-rule-action-examples"></a>

The following JSON example defines a republish action in an AWS IoT rule.

```
{
    "topicRulePayload": {
        "sql": "SELECT * FROM 'some/topic'", 
        "ruleDisabled": false, 
        "awsIotSqlVersion": "2016-03-23",
        "actions": [
            {
                "republish": {
                    "topic": "another/topic",
                    "qos": 1,
                    "roleArn": "arn:aws:iam::123456789012:role/aws_iot_republish"
                }
            }
        ]
    }
}
```

The following JSON example defines a republish action with substitution templates in an AWS IoT rule.

```
{
    "topicRulePayload": {
        "sql": "SELECT * FROM 'some/topic'",
        "ruleDisabled": false,
        "awsIotSqlVersion": "2016-03-23",
        "actions": [
            {
                "republish": {
                    "topic": "${topic()}/republish",
                    "roleArn": "arn:aws:iam::123456789012:role/aws_iot_republish"
                }
            }
        ]
    }
}
```

The following JSON example defines a republish action with `headers` in an AWS IoT rule.

```
{
    "topicRulePayload": {
        "sql": "SELECT * FROM 'some/topic'",
        "ruleDisabled": false,
        "awsIotSqlVersion": "2016-03-23",
        "actions": [
            {
                "republish": {
                    "topic": "${topic()}/republish",
                    "roleArn": "arn:aws:iam::123456789012:role/aws_iot_republish",
                    "headers": {
                        "payloadFormatIndicator": "UTF8_DATA",
                        "contentType": "rule/contentType",
                        "correlationData": "cnVsZSBjb3JyZWxhdGlvbiBkYXRh",
                        "userProperties": [
                            {
                                "key": "ruleKey1",
                                "value": "ruleValue1"
                            },
                            {
                                "key": "ruleKey2",
                                "value": "ruleValue2"
                            }
                        ]
                    }
                }
            }
        ]
    }
}
```

**Note**  
The original source IP won't be passed though [Republish action](#republish-rule-action).