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Creating an email trigger that sends messages to WebSocket connections

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Updated at May 13, 2025

Create an email trigger to send messages to Yandex API Gateway WebSocket connections when an email arrives. The service automatically generates an email address when creating the trigger.

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.

  • Optionally, a bucket to save email attachments to. If you do not have a bucket, create one with restricted access.

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:

    • Optionally, enter a trigger name and description.
    • In the Type field, select Email.
    • In the Launched resource field, select API gateway.

  6. Optionally, under Settings for saving attachments:

    • In the Bucket field, select the bucket to save email attachments to.
    • In the Service account field, specify a service account authorized to upload objects to the Object Storage bucket.

  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 mail \
  --name <trigger_name> \
  --batch-size <batch_size> \
  --batch-cutoff <maximum_timeout> \
  --attachements-bucket <bucket_name> \
  --attachements-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>

Where:

  • --name: Trigger name.
  • --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.

  • --attachements-bucket: Name of the bucket to save email attachments to. This is an optional parameter.

  • --attachements-service-account-id: ID of the service account authorized to upload objects to the Object Storage bucket. This is an optional parameter.

  • --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: a1sfe084v4h2********
folder_id: b1g88tflruh2********
created_at: "2023-08-04T08:45:31.131391Z"
name: mail-trigger
rule:
  mail:
    email: a1s8h8avglh2********-cho1****@serverless.yandexcloud.net
    batch_settings:
      size: "3"
      cutoff: 20s
    gateway_websocket_broadcast:
      gateway_id: d4eofc7n0mh2********
      path: /
      service_account_id: aje3932acdh2********
status: ACTIVE

To create an email trigger, use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call.

Yandex API Gateway will automatically generate an email address that will cause the trigger to fire when messages are sent to it. To see it, retrieve detailed trigger information.

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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Creating a trigger for Data Streams
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Updating a trigger