[Yandex Cloud documentation](../../../index.md) > [Yandex Cloud Functions](../../index.md) > [Step-by-step guides](../index.md) > Creating a trigger > Creating a Telegram trigger

# Creating a Telegram trigger that invokes a function from Cloud Functions

Create a [Telegram trigger](../../concepts/trigger/telegram-trigger.md) that invokes a [function](../../concepts/function.md) from Cloud Functions when your Telegram bot receives an update.

## Getting started {#before-you-begin}

To create a trigger, you will need:

* Telegram bot and its token. If you do not have a bot, create one using [@BotFather](https://core.telegram.org/bots/features#botfather) and copy the issued token.

* Function the trigger will invoke. If you do not have a function:

    * [Create a function](../function/function-create.md).
    * [Create a function version](../function/version-manage.md).

* Optionally, a [dead-letter queue](../../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 the following permissions:

    * To invoke a function.
    * Optionally, to write to a 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).

## 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 your trigger.

    1. [Navigate](https://console.yandex.cloud/link/functions) 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**:

        * Optionally, enter a trigger name and description.

        * In the **Labels** field, click **Add label** and specify the labels in `key: value` format.

        * In the **Type** field, select `Telegram`.

    1. Under **Telegram settings**, specify the Telegram bot token you received from [@BotFather](https://core.telegram.org/bots/features#botfather).

    1. Under **Batch message settings**, specify the following:
       
       * **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 1,000. The default value is 1.
       
       The trigger groups events within the specified wait time and sends them to the target. The number of events cannot exceed the specified batch size.

    1. Under **Targets**:

        1. In the **Target type** field, select `Function`.

        1. Under **Function settings**, select a function and specify:

            * [Function version tag](../../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. Optionally, in the **Filter** field, specify a jq template to filter events sent to the target. If no filter is specified, all events are sent to the target.

        1. Optionally, in the **Transformation template** field, specify a `jq` template to transform events before sending them to the target. If no template is specified, no transformations apply to the events.

    1. Click **Create trigger**.

- Terraform {#tf}

    With [Terraform](https://www.terraform.io/), 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](https://github.com/hashicorp/terraform/blob/main/LICENSE). The [Yandex Cloud provider for Terraform](https://github.com/yandex-cloud/terraform-provider-yandex) is distributed under the [MPL-2.0](https://www.mozilla.org/en-US/MPL/2.0/) license.
    
    For more information about the provider resources, see the guides on the [Terraform](https://www.terraform.io/docs/providers/yandex/index.html) website or [its mirror](../../../terraform/index.md).

    If you do not have Terraform yet, [install it and configure the Yandex Cloud provider](../../../tutorials/infrastructure-management/terraform-quickstart.md#install-terraform).
    
    
    To manage infrastructure using Terraform under a service account or user accounts (a Yandex account, a federated account, or a local user), [authenticate](../../../terraform/authentication.md) using the appropriate method.

    To create a Telegram trigger that invokes a function:

    1. Describe the trigger in the configuration file:

       ```hcl
       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 {
           invoke_function {
             function_id        = "<function_ID>"
             function_tag       = "<function_version_tag>"
             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](https://core.telegram.org/bots/features#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](https://core.telegram.org/bots/api#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 that the trigger calls multiple resources, including those of different types. There are [limits](../../concepts/limits.md#functions-limits) on the maximum number of resources.
       
           * `invoke_function`: Function settings:
       
               * `function_id`: Function ID.
               * `function_tag`: Function version tag. This is an optional parameter. If it is not specified, the latest version of the function is called.
               * `service_account_id`: ID of the service account with permissions to invoke the function.
       
           * `filter`: Filtering events before sending them to the target. This is an optional section.
           
               * `jq`: [jq template](https://jqlang.github.io/jq/manual/) 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](../../../terraform/resources/serverless_triggers.md).

    1. Create the resources:

        1. In the terminal, navigate to the configuration file directory.
        1. Make sure the configuration is correct using this command:
        
           ```bash
           terraform validate
           ```
        
           If the configuration is valid, you will get this message:
        
           ```bash
           Success! The configuration is valid.
           ```
        
        1. Run this command:
        
           ```bash
           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.
        1. Apply the configuration changes:
        
           ```bash
           terraform apply
           ```
        
        1. 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](https://console.yandex.cloud) or this [CLI](../../../cli/quickstart.md) command:

        ```bash
        yc serverless trigger list
        ```

{% endlist %}

## Checking the result {#check-result}

Check that the trigger works correctly. To do this, view [function logs](../function/function-logs.md) that show information on invocations.

#### Useful links {#see-also}

* [Creating a Telegram Trigger that invokes a container from Serverless Containers](../../../serverless-containers/operations/telegram-trigger-create.md)
* [How to create a Telegram trigger that sends messages to WebSocket connections](../../../api-gateway/operations/trigger/telegram-trigger-create.md)