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Creating a trigger for Object Storage that sends messages to WebSocket connections

Written by
Updated at November 14, 2024

Create a trigger for Object Storage to send messages to WebSocket connections when you create, move, or delete an object in a bucket.

Getting started

To create a trigger, you need:

  • API gateway. Messages will be sent to WebSocket connections connected to the API gateway. If you do not have an API gateway, create one.

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

  • Bucket whose object events will fire the trigger. 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:

    • Enter a name and description for the trigger.
    • In the Type field, select Object Storage.
    • In the Launched resource field, select API gateway.

  6. Under Object Storage settings:

    • In the Bucket field, select the bucket whose object events you want to create a trigger for.
    • In the Event types field, select the events that will fire the trigger.
    • (Optional) In the Object key prefix field, enter a prefix for filtering.
    • (Optional) In the Object key suffix field, enter a suffix for filtering.

  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 events for a period not exceeding the specified wait time and sends them to WebSocket connections. The number of events 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 command line interface yet, install and initialize it.

The folder specified in the CLI profile is used by default. 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 object-storage \
    --name <trigger_name> \
    --bucket-id <bucket_ID> \
    --prefix '<object_key_prefix>' \
    --suffix '<object_key_suffix>' \
    --events 'create-object','delete-object','update-object' \
    --batch-size <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.
  • --bucket-id: Bucket ID.
  • --prefix: Bucket object key prefix. This is an optional parameter. It is used for filtering.
  • --suffix: Bucket object key suffix. This is an optional parameter. It is used for filtering.
  • --events: Events activating the trigger.
  • --batch-size: Event 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 1 to 60 seconds. The default value is 1 second. The trigger groups events for a period not exceeding batch-cutoff and sends them to WebSocket connections. The number of events 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: "2023-08-24T15:19:15.353909857Z"
name: os-trigger
rule:
  object_storage:
    event_type:
    - OBJECT_STORAGE_EVENT_TYPE_CREATE_OBJECT
    - OBJECT_STORAGE_EVENT_TYPE_DELETE_OBJECT
    - OBJECT_STORAGE_EVENT_TYPE_UPDATE_OBJECT
    bucket_id: s3-for-trigger
    prefix: dev
    suffix: 12.jpg
    batch_settings:
      size: "3"
      cutoff: 20s
    gateway_websocket_broadcast:
      gateway_id: d4eofc7n0mh2********
      path: /
      service_account_id: aje3932acdh2********
status: ACTIVE

To create a trigger for Object Storage, 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

Previous
Creating a trigger for Message Queue
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Creating a trigger for Container Registry