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Creating a trigger that sends messages to WebSocket connections from an Yandex IoT Core broker

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Updated at May 13, 2025

Create a trigger for an Yandex IoT Core broker topic and send message copies to Yandex API Gateway WebSocket connections.

Warning

The trigger must be in the same cloud as the broker whose topic it reads messages from.

Getting started

To create a trigger, you will need:

  • API gateway. Messages will be sent to WebSocket connections accessing the API gateway at the path specified in the trigger settings. If you do not have an API gateway, create one.

    Note

    The trigger does not call the API gateway when sending messages to WebSocket connections.

  • Service account with the api-gateway.websocketBroadcaster role. If you do not have a service account, create one.

  • Broker from the topic of which the trigger will collect message copies. If you do not have a broker, create one.

Creating a trigger

Note

The trigger is initiated within 5 minutes of being created.

  1. In the management console, select the folder where you want to create a trigger.

  2. Open API Gateway.

  3. In the left-hand panel, select Triggers.

  4. Click Create trigger.

  5. Under Basic settings:

    • Enter a name and description for the trigger.
    • In the Type field, select IoT Core (broker).
    • In the Launched resource field, select API gateway.

  6. Under IoT Core message settings:

    • In the Broker field, specify the broker.
    • (Optional) In the MQTT topic field, specify an MQTT topic. If no MQTT topic is set, the trigger will fire for all broker topics.

  7. Under Batch message settings, specify:

    • Batch size. The values may range from 1 to 1,000. The default value is 1.
    • Maximum wait time. The values may range from 1 to 60 seconds. The default value is 1 second.

    The trigger groups messages for a period not exceeding the specified wait time and sends them to WebSocket connections. The number of messages cannot exceed the specified batch size.

  8. Under API gateway settings:

    • In the API gateway field, select the API gateway.
    • In the Path field, specify the path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
    • In the Service account field, select the service account to send messages to WebSocket connections.

  9. Click Create trigger.

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To create a trigger that sends messages to WebSocket connections, run this command:

yc serverless trigger create iot-broker \
  --name <trigger_name> \
  --broker-id <broker_ID> \
  --mqtt-topic '<broker_MQTT_topic>' \
  --batch-size <message_group_size> \
  --batch-cutoff <maximum_timeout> \
  --gateway-id <API_gateway_ID> \
  --gateway-websocket-broadcast-path <path> \
  --gateway-websocket-broadcast-service-account-id <service_account_ID>

Where:

  • --name: Trigger name.
  • --broker-id: Broker ID.
  • --mqtt-topic: MQTT topic you want to create a trigger for. This is an optional parameter. If this parameter is skipped, the trigger will fire for all broker topics.
  • --batch-size: Message batch size. This is an optional parameter. The values may range from 1 to 10. The default value is 1.
  • --batch-cutoff: Maximum wait time. This is an optional parameter. The values may range from 0 to 20 seconds. The default value is 10 seconds. The trigger groups messages for a period not exceeding batch-cutoff and sends them to WebSocket connections. The number of messages cannot exceed batch-size.
  • --gateway-id: API gateway ID.
  • --gateway-websocket-broadcast-path: Path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
  • --gateway-websocket-broadcast-account-id: Service account ID with permissions to send messages to WebSocket connections.

Result:

id: a1s5msktijh2********
folder_id: b1gmit33hgh2********
created_at: "2022-10-24T15:19:15.353909857Z"
name: iot-broker-trigger
rule:
  iot_broker_message:
    broker_id: arenou2oj4h2********
    mqtt_topic: topic-for-broker
    batch_settings:
      size: "1"
      cutoff: 0s
    gateway_websocket_broadcast:
      gateway_id: d4eofc7n0mh2********
      path: /
      service_account_id: aje3932acdh2********
status: ACTIVE

To create a trigger for Yandex IoT Core, use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call.

Checking the result

Check that the trigger operates correctly. Do it by viewing the API gateway logs that present information about its incoming requests.

See also

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