How to create a Telegram trigger that sends messages to WebSocket connections

With Terraform, you can quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. These files store the infrastructure description written in HashiCorp Configuration Language (HCL). If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.

Terraform is distributed under the Business Source License. The Yandex Cloud provider for Terraform is distributed under the MPL-2.0 license.

For more information about the provider resources, see the guides on the Terraform website or its mirror.

If you do not have Terraform yet, install it and configure the Yandex Cloud provider.

To manage infrastructure using Terraform under a service account or user accounts (a Yandex account, a federated account, or a local user), authenticate using the appropriate method.

To create a trigger for Telegram that sends messages to WebSocket connections:

1. Describe the trigger in the configuration file:

   resource "yandex_serverless_triggers" "my_trigger" {
     name = "<trigger_name>"
     source {
       telegram_message {
         bot_token       = "<Telegram_bot_token>"
         allowed_updates = [ "<update_type>", "<update_type>" ]
         force           = true
       }
     }
     action {
       gateway_websocket_broadcast {
         gateway_id         = "<API_gateway_ID>"
         path               = "<WebSocket_connection_path>"
         service_account_id = "<service_account_ID>"
       }
       filter {
         jq = ".message.text | startswith(\"/\")"
       }
       transformer {
         jq = ".message"
       }
       retry_policy {
         retry_attempts = "<number_of_retries>"
         interval       = "<interval_between_retries>"
       }
       dead_letter {
         dead_letter_queue {
           queue_arn          = "<Dead_Letter_Queue_ARN>"
           service_account_id = "<service_account_ID>"
         }
       }
     }
   }
   

   Where:

   • name: Trigger name. The name format is as follows:

     • Length: between 3 and 63 characters.
     • It can only contain lowercase Latin letters, numbers, and hyphens.
     • It must start with a letter and cannot end with a hyphen.

   • description: Trigger description. This is an optional parameter.

   • labels: Trigger labels in key:value format. This is an optional parameter.

   • source: Event source settings:

     • telegram_message: Telegram bot settings:

       • bot_token: Telegram bot token received from @BotFather. The value is only provided when creating or updating a trigger. Terraform does not return the value in its output. When the token changes, the webhook is re-registered.
       • allowed_updates: List of Telegram update types the bot subscribes to. This is an optional setting. The default value is [ "message" ].
       • force: Reinstalling the webhook if the bot already has a webhook configured for another URL. Without this setting, creating a trigger will fail with an error. If the webhook already points to the trigger, this setting has no effect. This is an optional parameter.

   • action: Target settings. You can specify this section multiple times so the trigger calls multiple resources, including those of different types. There are limits on the maximum number of resources.

     • gateway_websocket_broadcast: API gateway settings:

       • gateway_id: API gateway ID.
       • path: Path in the OpenAPI specification. Events will be sent through WebSocket connections established using this path.
       • service_account_id: ID of the service account with permissions to send events to WebSocket connections.

     • filter: Filtering events before sending them to the target. This is an optional section.

       • jq: jq template to filter events sent to the target. It not specified, all events reach the target.

     • transformer: Transforming events before sending them to the target. This is an optional section.

       • jq: jq template to transform events before sending them to the target. It omitted, no transformations apply to the events.

     • retry_policy: Repeated request settings. This is an optional section.

       • interval: Time interval before a retry attempt to send the event if the current attempt fails.
       • retry_attempts: Number of retry attempts before the trigger moves the event to the dead-letter queue.

     • dead_letter: Dead-letter queue settings. This is an optional section.

       • dead_letter_queue: Queue settings:

         • queue_arn: Queue ARN.
         • service_account_id: ID of the service account with permissions to write to the queue.
         • message_attributes: Attributes to add to each message in the queue, in key:value format. This is an optional parameter.

   For more on the properties of the yandex_serverless_triggers resource, see this provider guide.

2. Create the resources:

   1. In the terminal, navigate to the configuration file directory.

   2. Make sure the configuration is correct using this command:

      terraform validate
      

      If the configuration is valid, you will get this message:

      Success! The configuration is valid.
      

   3. Run this command:

      terraform plan
      

      You will see a list of resources and their properties. No changes will be made at this step. Terraform will show any errors in the configuration.

   4. Apply the configuration changes:

      terraform apply
      

   5. Type yes and press Enter to confirm the changes.

   Terraform will create all the required resources. You can check the new resources using the management console or this CLI command:

   yc serverless trigger list