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Creating a trigger for Message Queue that sends messages to WebSocket connections

Written by
Updated at May 13, 2025

Create a trigger for Message Queue message queue to send messages to WebSocket connections.

Warning

  • You can only create a trigger for a standard message queue.
  • The trigger must be in the same cloud as the queue from which it reads messages.
  • Only one trigger can be created for each message queue.

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.

  • Message queue the trigger will collect messages from. If you do not have a queue, 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 Message Queue.
    • In the Launched resource field, select API gateway.

  6. Under Message Queue message settings, select a message queue and a service account with permissions to read messages from this queue.

  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 0 to 20 seconds. The default value is 10 seconds.

    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 message-queue \
    --name <trigger_name> \
    --queue <queue_ID> \
    --queue-service-account-id <service_account_ID> \
    --gateway-id <API_gateway_ID> \
    --gateway-websocket-broadcast-path <path> \
    --gateway-websocket-broadcast-service-account-id <service_account_ID> \
    --batch-size <message_group_size>
    --batch-cutoff <maximum_timeout>

Where:

  • --name: Trigger name.

  • --queue: Queue ID.

    To find out the queue ID:

    1. In the management console, select the folder containing the queue.
    2. Select Message Queue.
    3. Select the desired queue.
    4. You can see the queue ID under General information in the ARN field.

  • --queue-service-account-id: Service account with permissions to read messages from the queue.

  • --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.
  • --batch-size: Message batch size. This is an optional parameter. The values may range from 1 to 1,000. 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.

Result:

id: a1s5msktijh2********
folder_id: b1gmit33hgh2********
created_at: "2022-10-24T15:19:15.353909857Z"
name: ymq-trigger
rule:
  message_queue:
    queue_id: yrn:yc:ymq:ru-central1:b1gmit33ngh2********:my-mq
    service_account_id: bfbqqeo6jkh2********
    batch_settings:
      size: "1"
      cutoff: 10s
    gateway_websocket_broadcast:
      gateway_id: d4eofc7n0mh2********
      path: /
      service_account_id: aje3932acdh2********
status: ACTIVE

To create a trigger for Message Queue, 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.

Check that the number of enqueued messages is decreasing. To do this, view the queue statistics:

  1. In the management console, open Message Queue.
  2. Select the queue that you created the trigger for.
  3. Go to Monitoring. Check the Messages in the queue chart.

See also

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Creating a timer
Next
Creating a trigger for Object Storage