[Yandex Cloud documentation](../../index.md) > [Yandex IoT Core](../index.md) > [Step-by-step guides](index.md) > Creating a trigger for a topic > Broker # Creating a trigger for a broker topic {% note warning %} Yandex IoT Core is no longer available to new users. Current users can create resources until November 1, 2026. Afterwards, the service will go read-only and cease to operate on December 1, 2026. For more information on the timing and procedure, see [Service shutdown](../sunset.md). {% endnote %} Create a [trigger](../../functions/concepts/trigger/iot-core-trigger.md) for a Yandex IoT Core broker topic and process message copies using a [function](../../functions/concepts/function.md) in Cloud Functions. {% note warning %} The trigger must be in the same cloud as the broker whose topic it reads messages from. {% endnote %} ## Getting started {#before-you-begin} To create a trigger, you will need: * Function the trigger will invoke. If you do not have a function: * [Create a function](../../functions/operations/function/function-create.md). * [Create a function version](../../functions/operations/function/version-manage.md). * Optionally, a [dead-letter queue](../../functions/concepts/dlq.md) where to redirect the messages the function failed to process. If you do not have a queue, [create one](../../message-queue/operations/message-queue-new-queue.md). * [Service accounts](../../iam/concepts/users/service-accounts.md) with permissions to invoke the function and, optionally, write to the dead letter queue. You can use the same service account or different ones. If you do not have a service account, [create one](../../iam/operations/sa/create.md). * [Broker](../concepts/index.md#broker) whose topic the trigger will receive message copies from. If you do not have a broker, [create one](broker/broker-create.md). ## Creating a trigger {#trigger-create} {% note info %} The trigger is initiated within five minutes after it is created. {% endnote %} {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder where you want to create a trigger. 1. Navigate to **Cloud Functions**. 1. In the left-hand panel, select ![image](../../_assets/console-icons/gear-play.svg) **Triggers**. 1. Click **Create trigger**. 1. 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 `Function`. 1. Under **IoT Core message settings**: * In the **Broker** field, specify the broker. * Optionally, in the **MQTT topic** field, specify an MQTT topic. If no MQTT topic is set, the trigger fires for all broker topics. 1. Under **Batch message settings**, specify: * **Waiting time, s**​. The values may range from 1 to 60 seconds. The default value is 1 second. * **Batch size**​. The values may range from 1 to 100. The default value is 1. The trigger groups messages within the specified wait time period and sends them to the function. The number of messages cannot exceed the specified batch size. 1. Under **Function settings**, select a function and specify: * [Function version tag](../../functions/concepts/function.md#tag). * [Service account](../../iam/concepts/users/service-accounts.md) to use for invoking the function. 1. Optionally, under **Repeat request settings**: * In the **Interval** field, specify how long to wait before retrying the function if it fails. The values may range from 10 to 60 seconds. The default value is 10 seconds. * In the **Number of attempts** field, specify the number of function retries before the trigger sends a message to the dead letter queue. The values may range from 1 to 5. The default value is 1. 1. Optionally, under **Dead Letter Queue settings**, select a dead-letter queue and a service account with write permissions for that queue. 1. Click **Create trigger**. - CLI {#cli} If you do not have the Yandex Cloud CLI yet, [install and initialize it](../../cli/quickstart.md#install). The folder used by default is the one specified when [creating](../../cli/operations/profile/profile-create.md) the CLI profile. To change the default folder, use the `yc config set folder-id ` command. You can also specify a different folder for any command using `--folder-name` or `--folder-id`. If you access a resource by its name, the search will be limited to the default folder. If you access a resource by its ID, the search will be global, i.e., through all folders based on access permissions. To create a trigger that invokes a function, run this command: ```bash yc serverless trigger create iot-broker \ --name \ --broker-id \ --mqtt-topic '' \ --batch-size \ --batch-cutoff \ --invoke-function-id \ --invoke-function-service-account-id \ --retry-attempts \ --retry-interval \ --dlq-queue-id \ --dlq-service-account-id ``` Where: * `--name`: Trigger name. * `--broker-id`: [Broker ID](broker/broker-list.md). * `--mqtt-topic`: MQTT topic you want to create a trigger for. This is an optional setting. If you skip it, the trigger will fire for all broker topics. * `--batch-size`: Size of the message batch from MQTT topics. This is an optional parameter. The values may range from 1 to 10. The default value is 1. * `--batch-cutoff`: Maximum waiting time. This is an optional parameter. The values may range from 1 to 60 seconds. The default value is 1 second. The trigger groups messages for a period not exceeding `batch-cutoff` and sends them to a function. The number of messages cannot exceed `batch-size`. * `--invoke-function-id`: Function ID. * `--invoke-function-service-account-id`: ID of the service account with permissions to invoke the function. * `--retry-attempts`: Number of invocation retries before the trigger sends a message to the dead-letter queue. This is an optional setting. The values may range from 1 to 5. The default value is 1. * `--retry-interval`: Time to wait before retrying the function if it fails. This is an optional setting. The values may range from 10 to 60 seconds. The default value is 10 seconds. * `--dlq-queue-id`: Dead-letter queue ID. This is an optional setting. * `--dlq-service-account-id`: ID of the service account with write permissions for the dead-letter queue. This is an optional setting. Result: ```text id: a1sl0mkmimfj******** folder_id: b1g88tflru0e******** created_at: "2019-09-25T13:54:35.654935Z" name: iot-broker-trigger rule: iot_broker_message: broker_id: arenou2oj4********** mqtt_topic: topic-for-broker batch_settings: size: "1" cutoff: 0s invoke_function: function_id: d4eofc7n0m03******** function_tag: $latest service_account_id: aje3932acd0c******** retry_settings: retry_attempts: "1" interval: 10s status: ACTIVE ``` - API {#api} To create a trigger for Yandex IoT Core, use the [create](../../functions/triggers/api-ref/Trigger/create.md) REST API method for the [Trigger](../../functions/triggers/api-ref/Trigger/index.md) resource or the [TriggerService/Create](../../functions/triggers/api-ref/grpc/Trigger/create.md) gRPC API call. {% endlist %} ## Checking the result {#check-result} Check that the trigger works correctly. To do this, view [function logs](../../functions/operations/function/function-logs.md) that show information on invocations. ## Useful links {#see-also} * [Creating a trigger that will send messages to a container in Serverless Containers from a Yandex IoT Core broker topic](../../serverless-containers/operations/iot-core-trigger-broker-create.md) * [Creating a trigger that sends messages to WebSocket connections from a Yandex IoT Core broker topic](../../api-gateway/operations/trigger/iot-core-trigger-broker-create.md)