MQTT bridge

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MQTT bridge - AWS IoT Greengrass

Versions Type Operating system Requirements Dependencies Configuration Local log file Changelog

The MQTT bridge component (aws.greengrass.clientdevices.mqtt.Bridge) relays MQTT messages between client devices, local Greengrass publish/subscribe, and AWS IoT Core. You can use this component to act on MQTT messages from client devices in custom components and sync client devices with the AWS Cloud.

Note

Client devices are local IoT devices that connect to a Greengrass core device to send MQTT messages and data to process. For more information, see Interact with local IoT devices.

You can use this component to relay messages between the following message brokers:

Local MQTT – The local MQTT broker handles messages between client devices and a core device.
Local publish/subscribe – The local Greengrass message broker handles messages between components on a core device. For more information about how to interact with these messages in Greengrass components, see Publish/subscribe local messages.
AWS IoT Core – The AWS IoT Core MQTT broker handles messages between IoT devices and AWS Cloud destinations. For more information about how to interact with these messages in Greengrass components, see Publish/subscribe AWS IoT Core MQTT messages.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

Versions

This component has the following versions:

2.3.x
2.2.x
2.1.x
2.0.x

Type

This component is a plugin component (aws.greengrass.plugin). The Greengrass nucleus runs this component in the same Java Virtual Machine (JVM) as the nucleus. The nucleus restarts when you change this component's version on the core device.

This component uses the same log file as the Greengrass nucleus. For more information, see Monitor AWS IoT Greengrass logs.

For more information, see Component types.

Operating system

This component can be installed on core devices that run the following operating systems:

Linux
Windows

Requirements

This component has the following requirements:

If you configure the core device's MQTT broker component to use a port other than the default port 8883, you must use MQTT bridge v2.1.0 or later. Configure it to connect on the port where the broker operates.
The MQTT bridge component is supported to run in a VPC.

Dependencies

When you deploy a component, AWS IoT Greengrass also deploys compatible versions of its dependencies. This means that you must meet the requirements for the component and all of its dependencies to successfully deploy the component. This section lists the dependencies for the released versions of this component and the semantic version constraints that define the component versions for each dependency. You can also view the dependencies for each version of the component in the AWS IoT Greengrass console. On the component details page, look for the Dependencies list.

2.3.2

The following table lists the dependencies for version 2.3.2 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.6.0	Hard

2.3.0 and 2.3.1

The following table lists the dependencies for version 2.3.0 and 2.3.1 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.5.0	Hard

2.2.5 and 2.2.6

The following table lists the dependencies for version 2.2.5 and 2.2.6 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.5.0	Hard

2.2.3 and 2.2.4

The following table lists the dependencies for versions 2.2.3 and 2.2.4 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.4.0	Hard

2.2.0 – 2.2.2

The following table lists the dependencies for versions 2.2.0 to 2.2.2 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.3.0	Hard

2.1.1

The following table lists the dependencies for version 2.1.1 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.0.0 <2.2.0	Hard

2.0.0 to 2.1.0

The following table lists the dependencies for versions 2.0.0 through 2.1.0 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.0.0 <2.1.0	Hard

anchor anchor anchor anchor anchor anchor anchor

The following table lists the dependencies for version 2.3.2 of this component.

Dependency	Compatible versions	Dependency type
Client device auth	>=2.2.0 <2.6.0	Hard

For more information about component dependencies, see the component recipe reference.

Configuration

This component provides the following configuration parameters that you can customize when you deploy the component.

2.3.0 – 2.3.2

mqttTopicMapping

The topic mappings that you want to bridge. This component subscribes to messages on the source topic and publishes the messages that it receives to the destination topic. Each topic mapping defines the topic, source type, and destination type.

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

You can use the + and # MQTT topic wildcards to relay messages on all topics that match a topic filter. For more information, see MQTT topics in the AWS IoT Core Developer Guide.

Note

To use MQTT topic wildcards with the Pubsub source broker, you must use v2.6.0 or later of the Greengrass nucleus component.

targetTopicPrefix

The prefix to add to the target topic when this component relays the message.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

mqtt5RouteOptions

(Optional) Provides options for configuring topic mappings for bridging messages from the source topic to the destination topic.

This object contains the following information:

mqtt5RouteOptionsNameKey

The name of the route options for a topic mapping. Replace mqtt5RouteOptionsNameKey with the matching topicMappingNameKey defined in the mqttTopicMapping field.

This object contains the following information:

noLocal

(Optional) When enabled, the bridge doesn't forward messages on a topic that the bridge itself published. Use this to prevent loops, as follows:


{
    "mqtt5RouteOptions": {
        "toIoTCore": {
            "noLocal": true
        }
    },
    "mqttTopicMapping": {
        "toIoTCore": {
            "topic": "device",
            "source": "LocalMqtt",
            "target": "IotCore"
        },
        "toLocal": {
            "topic": "device",
            "source": "IotCore",
            "target": "LocalMqtt"
        }
    }
}

noLocal is only supported for routes where the source is LocalMqtt.

Default: false

retainAsPublished

(Optional) When enabled, messages forwarded by the bridge have the same retain flag as messages published to the broker for that route.

retainAsPublished is only supported for routes where the source is LocalMqtt.

Default: false

mqtt

(Optional) MQTT protocol settings for communicating with the local broker.

version

(Optional) The MQTT protocol version used by the bridge to communicate with the local broker. Must be the same as the MQTT version selected in the nucleus configuration.

Choose from the following:

mqtt3
mqtt5

You must deploy an MQTT broker when the source or target field of the mqttTopicMapping object is set to LocalMqtt. If you choose the mqtt5 option you must use the MQTT 5 broker (EMQX).

Default: mqtt3

ackTimeoutSeconds

(Optional) Time interval to wait for PUBACK, SUBACK, or UNSUBACK packets before failing the operation.

Default: 60

connAckTimeoutMs

(Optional) Time interval to wait for a CONNACK packet before shutting down the connection.

Default: 20000 (20 seconds)

pingTimeoutMs

(Optional) The amount of time in milliseconds that the bridge waits to receive a PINGACK message from the local broker. If the wait exceeds the timeout, the bridge closes then reopens the MQTT connection. This value must be less than keepAliveTimeoutSeconds.

Default: 30000 (30 seconds)

keepAliveTimeoutSeconds

(Optional) The amount of time in seconds between each PING message that the bridge sends to keep the MQTT connection alive. This value must be greater than pingTimeoutMs.

Default: 60

maxReconnectDelayMs

(Optional) The maximum amount of time in seconds for MQTT to reconnect.

Default: 30000 (30 seconds)

minReconnectDelayMs

(Optional) The minimum amount of time in seconds for MQTT to reconnect.

receiveMaximum

(Optional) The maximum number of unacknowledged QoS1 packets the bridge can send.

Default: 100

maximumPacketSize

The maximum number of bytes the client will accept for an MQTT packet.

Default: null (No limit)

sessionExpiryInterval

(Optional) The amount of time in seconds you can request for a session to last between the bridge and the local broker.

Default: 4294967295 (session never expires)

brokerUri

(Optional) The URI of the local MQTT broker. You must specify this parameter if you configure the MQTT broker to use a different port than the default port 8883. Use the following format, and replace port with the port where the MQTT broker operates: ssl://localhost:port.

Default: ssl://localhost:8883

startupTimeoutSeconds

(Optional) The maximum of time in seconds for the component to start. The component's state changes to BROKEN if it exceeds this timeout.

Default: 120

Example: Configuration merge update

The following example configuration update specifies the following:

Relay messages from client devices to AWS IoT Core on topics that match the clients/+/hello/world topic filter.
Relay messages from client devices to local publish/subscribe on topics that match the clients/+/detections topic filter, and add the events/input/ prefix to the target topic. The resulting target topic matches the events/input/clients/+/detections topic filter.
Relay messages from client devices to AWS IoT Core on topics that match the clients/+/status topic filter, and add the $aws/rules/StatusUpdateRule/ prefix to the target topic. This example relays these messages directly to an AWS IoT rule named StatusUpdateRule to reduce costs using Basic Ingest.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDeviceEvents": {
      "topic": "clients/+/detections",
      "targetTopicPrefix": "events/input/",
      "source": "LocalMqtt",
      "target": "Pubsub"
    },
    "ClientDeviceCloudStatusUpdate": {
      "topic": "clients/+/status",
      "targetTopicPrefix": "$aws/rules/StatusUpdateRule/",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

Example: Configuring MQTT 5

The following example configuration updates the following:

Enables the bridge to use the MQTT 5 protocol with the local broker.
Configures MQTT retain as published setting for the ClientDeviceHelloWorld topic mapping.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  },
  "mqtt5RouteOptions": {
    "ClientDeviceHelloWorld": {
      "retainAsPublished": true
    }
  },
  "mqtt": {
    "version": "mqtt5"
  }
}

2.2.6

mqttTopicMapping

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

You can use the + and # MQTT topic wildcards to relay messages on all topics that match a topic filter. For more information, see MQTT topics in the AWS IoT Core Developer Guide.

Note

To use MQTT topic wildcards with the Pubsub source broker, you must use v2.6.0 or later of the Greengrass nucleus component.

targetTopicPrefix

The prefix to add to the target topic when this component relays the message.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

brokerUri

Default: ssl://localhost:8883

startupTimeoutSeconds

(Optional) The maximum of time in seconds for the component to start. The component's state changes to BROKEN if it exceeds this timeout.

Default: 120

Example: Configuration merge update

The following example configuration update specifies the following:

Relay messages from client devices to AWS IoT Core on topics that match the clients/+/hello/world topic filter.
Relay messages from client devices to local publish/subscribe on topics that match the clients/+/detections topic filter, and add the events/input/ prefix to the target topic. The resulting target topic matches the events/input/clients/+/detections topic filter.
Relay messages from client devices to AWS IoT Core on topics that match the clients/+/status topic filter, and add the $aws/rules/StatusUpdateRule/ prefix to the target topic. This example relays these messages directly to an AWS IoT rule named StatusUpdateRule to reduce costs using Basic Ingest.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDeviceEvents": {
      "topic": "clients/+/detections",
      "targetTopicPrefix": "events/input/",
      "source": "LocalMqtt",
      "target": "Pubsub"
    },
    "ClientDeviceCloudStatusUpdate": {
      "topic": "clients/+/status",
      "targetTopicPrefix": "$aws/rules/StatusUpdateRule/",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

2.2.0 - 2.2.5

mqttTopicMapping

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

You can use the + and # MQTT topic wildcards to relay messages on all topics that match a topic filter. For more information, see MQTT topics in the AWS IoT Core Developer Guide.

Note

To use MQTT topic wildcards with the Pubsub source broker, you must use v2.6.0 or later of the Greengrass nucleus component.

targetTopicPrefix

The prefix to add to the target topic when this component relays the message.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

brokerUri

Default: ssl://localhost:8883

Example: Configuration merge update

The following example configuration update specifies the following:

Relay messages from client devices to AWS IoT Core on topics that match the clients/+/hello/world topic filter.
Relay messages from client devices to local publish/subscribe on topics that match the clients/+/detections topic filter, and add the events/input/ prefix to the target topic. The resulting target topic matches the events/input/clients/+/detections topic filter.
Relay messages from client devices to AWS IoT Core on topics that match the clients/+/status topic filter, and add the $aws/rules/StatusUpdateRule/ prefix to the target topic. This example relays these messages directly to an AWS IoT rule named StatusUpdateRule to reduce costs using Basic Ingest.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDeviceEvents": {
      "topic": "clients/+/detections",
      "targetTopicPrefix": "events/input/",
      "source": "LocalMqtt",
      "target": "Pubsub"
    },
    "ClientDeviceCloudStatusUpdate": {
      "topic": "clients/+/status",
      "targetTopicPrefix": "$aws/rules/StatusUpdateRule/",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

2.1.x

mqttTopicMapping

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

If you specify the LocalMqtt or IotCore source broker, you can use the + and # MQTT topic wildcards to relay messages on all topics that match a topic filter. For more information, see MQTT topics in the AWS IoT Core Developer Guide.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

brokerUri

Default: ssl://localhost:8883

Example: Configuration merge update

The following example configuration update specifies to relay messages from client devices to AWS IoT Core on the clients/MyClientDevice1/hello/world and clients/MyClientDevice2/hello/world topics.


{
  "mqttTopicMapping": {
    "ClientDevice1HelloWorld": {
      "topic": "clients/MyClientDevice1/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDevice2HelloWorld": {
      "topic": "clients/MyClientDevice2/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

2.0.x

mqttTopicMapping

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

Example: Configuration merge update


{
  "mqttTopicMapping": {
    "ClientDevice1HelloWorld": {
      "topic": "clients/MyClientDevice1/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDevice2HelloWorld": {
      "topic": "clients/MyClientDevice2/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

anchor anchor anchor anchor anchor

mqttTopicMapping

This object contains the following information:

topicMappingNameKey

The name of this topic mapping. Replace topicMappingNameKey with a name that helps you identify this topic mapping.

This object contains the following information:

topic

The topic or topic filter to bridge between the source and target brokers.

You can use the + and # MQTT topic wildcards to relay messages on all topics that match a topic filter. For more information, see MQTT topics in the AWS IoT Core Developer Guide.

Note

To use MQTT topic wildcards with the Pubsub source broker, you must use v2.6.0 or later of the Greengrass nucleus component.

targetTopicPrefix

The prefix to add to the target topic when this component relays the message.

source

The source message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

target

The target message broker. Choose from the following options:

LocalMqtt – The local MQTT broker where client devices communicate.
Pubsub – The local Greengrass publish/subscribe message broker.
IotCore – The AWS IoT Core MQTT message broker.

Note
The MQTT bridge uses QoS 1 to publish and subscribe to AWS IoT Core, even when a client device uses QoS 0 to publish and subscribe to the local MQTT broker. As a result, you might observe additional latency when you relay MQTT messages from client devices on the local MQTT broker to AWS IoT Core. For more information about MQTT configuration on core devices, see Configure MQTT timeouts and cache settings.

source and target must be different.

mqtt5RouteOptions

(Optional) Provides options for configuring topic mappings for bridging messages from the source topic to the destination topic.

This object contains the following information:

mqtt5RouteOptionsNameKey

The name of the route options for a topic mapping. Replace mqtt5RouteOptionsNameKey with the matching topicMappingNameKey defined in the mqttTopicMapping field.

This object contains the following information:

noLocal

(Optional) When enabled, the bridge doesn't forward messages on a topic that the bridge itself published. Use this to prevent loops, as follows:


{
    "mqtt5RouteOptions": {
        "toIoTCore": {
            "noLocal": true
        }
    },
    "mqttTopicMapping": {
        "toIoTCore": {
            "topic": "device",
            "source": "LocalMqtt",
            "target": "IotCore"
        },
        "toLocal": {
            "topic": "device",
            "source": "IotCore",
            "target": "LocalMqtt"
        }
    }
}

noLocal is only supported for routes where the source is LocalMqtt.

Default: false

retainAsPublished

(Optional) When enabled, messages forwarded by the bridge have the same retain flag as messages published to the broker for that route.

retainAsPublished is only supported for routes where the source is LocalMqtt.

Default: false

mqtt

(Optional) MQTT protocol settings for communicating with the local broker.

version

(Optional) The MQTT protocol version used by the bridge to communicate with the local broker. Must be the same as the MQTT version selected in the nucleus configuration.

Choose from the following:

mqtt3
mqtt5

You must deploy an MQTT broker when the source or target field of the mqttTopicMapping object is set to LocalMqtt. If you choose the mqtt5 option you must use the MQTT 5 broker (EMQX).

Default: mqtt3

ackTimeoutSeconds

(Optional) Time interval to wait for PUBACK, SUBACK, or UNSUBACK packets before failing the operation.

Default: 60

connAckTimeoutMs

(Optional) Time interval to wait for a CONNACK packet before shutting down the connection.

Default: 20000 (20 seconds)

pingTimeoutMs

Default: 30000 (30 seconds)

keepAliveTimeoutSeconds

(Optional) The amount of time in seconds between each PING message that the bridge sends to keep the MQTT connection alive. This value must be greater than pingTimeoutMs.

Default: 60

maxReconnectDelayMs

(Optional) The maximum amount of time in seconds for MQTT to reconnect.

Default: 30000 (30 seconds)

minReconnectDelayMs

(Optional) The minimum amount of time in seconds for MQTT to reconnect.

receiveMaximum

(Optional) The maximum number of unacknowledged QoS1 packets the bridge can send.

Default: 100

maximumPacketSize

The maximum number of bytes the client will accept for an MQTT packet.

Default: null (No limit)

sessionExpiryInterval

(Optional) The amount of time in seconds you can request for a session to last between the bridge and the local broker.

Default: 4294967295 (session never expires)

brokerUri

Default: ssl://localhost:8883

startupTimeoutSeconds

(Optional) The maximum of time in seconds for the component to start. The component's state changes to BROKEN if it exceeds this timeout.

Default: 120

Example: Configuration merge update

The following example configuration update specifies the following:

Relay messages from client devices to AWS IoT Core on topics that match the clients/+/hello/world topic filter.
Relay messages from client devices to local publish/subscribe on topics that match the clients/+/detections topic filter, and add the events/input/ prefix to the target topic. The resulting target topic matches the events/input/clients/+/detections topic filter.
Relay messages from client devices to AWS IoT Core on topics that match the clients/+/status topic filter, and add the $aws/rules/StatusUpdateRule/ prefix to the target topic. This example relays these messages directly to an AWS IoT rule named StatusUpdateRule to reduce costs using Basic Ingest.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    },
    "ClientDeviceEvents": {
      "topic": "clients/+/detections",
      "targetTopicPrefix": "events/input/",
      "source": "LocalMqtt",
      "target": "Pubsub"
    },
    "ClientDeviceCloudStatusUpdate": {
      "topic": "clients/+/status",
      "targetTopicPrefix": "$aws/rules/StatusUpdateRule/",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  }
}

Example: Configuring MQTT 5

The following example configuration updates the following:

Enables the bridge to use the MQTT 5 protocol with the local broker.
Configures MQTT retain as published setting for the ClientDeviceHelloWorld topic mapping.


{
  "mqttTopicMapping": {
    "ClientDeviceHelloWorld": {
      "topic": "clients/+/hello/world",
      "source": "LocalMqtt",
      "target": "IotCore"
    }
  },
  "mqtt5RouteOptions": {
    "ClientDeviceHelloWorld": {
      "retainAsPublished": true
    }
  },
  "mqtt": {
    "version": "mqtt5"
  }
}

Local log file

This component uses the same log file as the Greengrass nucleus component.

anchor anchor


/greengrass/v2/logs/greengrass.log

To view this component's logs

Run the following command on the core device to view this component's log file in real time. Replace /greengrass/v2 or C:\greengrass\v2 with the path to the AWS IoT Greengrass root folder.
Linux
```
sudo tail -f /greengrass/v2/logs/greengrass.log
```
Windows (PowerShell)
```
Get-Content C:\greengrass\v2\logs\greengrass.log -Tail 10 -Wait
```
anchor anchor
sudo tail -f /greengrass/v2/logs/greengrass.log

Changelog

The following table describes the changes in each version of the component.

Version	Changes
2.3.2	Version updated for client device auth version 2.5.0 release.
2.3.1	Bug fixes and improvements Fixes an issue where the local MQTT client gets into a disconnect loop.
2.3.0	New features Adds MQTT5 support for bridging between AWS IoT Core and local MQTT sources.
2.2.6	New features Adds a new `startupTimeoutSeconds` configuration option.
2.2.5	Version updated for client device auth version 2.4.0 release.
2.2.4	Version updated for Greengrass client device auth version 2.3.0 release.
2.2.3	This version contains bug fixes and improvements.
2.2.2	Bug fixes and improvements Logging adjustments.
2.2.1	Bug fixes and improvements Fixes issues that can result in the MQTT bridge failing to subscribe to MQTT topics.
2.2.0	New features Adds support for MQTT topic wildcards (`#` and `+`) when you specify local publish/subscribe as the source message broker. This feature requires v2.6.0 or later of the Greengrass nucleus component. Adds the `targetTopicPrefix` option, which you can specify to configure the MQTT bridge to add a prefix to the target topic when it relays a message.
2.1.1	Bug fixes and improvements Fixes issues with how this component handles configuration reset updates. Reduces the frequency of MQTT client disconnects when certificates rotate.
2.1.0	New features Adds the `brokerUri` parameter, which enables you to use a non-default MQTT broker port.
2.0.1	This version includes bug fixes and improvements.
2.0.0	Initial version.

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MQTT bridge

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Example: Configuration merge update

Example: Configuring MQTT 5

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Example: Configuration merge update

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Example: Configuration merge update

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Example: Configuration merge update

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Example: Configuration merge update

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Example: Configuration merge update

Example: Configuring MQTT 5

Local log file

To view this component's logs

Changelog

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