Creating a timer that invokes a Cloud Functions function

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 invokes a function, run this command:

yc serverless trigger create timer \
  --name <timer_name> \
  --cron-expression '<cron_expression>' \
  --payload <message> \
  --invoke-function-id <function_ID> \
  --invoke-function-service-account-id <service_account_ID> \
  --retry-attempts <number_of_retry_invocation_attempts> \
  --retry-interval <interval_between_retry_attempts> \
  --dlq-queue-id <dead_letter_queue_ID> \
  --dlq-service-account-id <service_account_ID>

Where:

• --name: Timer name.
• --cron-expression: Function invocation schedule specified as a cron expression.
• --payload: Message that will be sent to the function if the timer fires. The string length must not exceed 4,096 characters.

• --invoke-function-id: Function ID.
• --invoke-function-service-account-id: ID of the service account with permissions to invoke the function.
• --retry-attempts: Number of invocation retries before the trigger moves a message to the dead-letter queue. This is an optional parameter. The values may range from 1 to 5. The default value is 1.
• --retry-interval: Time after which the function will be invoked again if the current attempt fails. This is an optional parameter. The values may range from 10 to 60 seconds. The default value is 10 seconds.
• --dlq-queue-id: Dead-letter queue ID. This is an optional parameter.
• --dlq-service-account-id: ID of the service account with write permissions to the dead-letter queue. This is an optional parameter.

Result:

id: a1sfe084v4**********
folder_id: b1g88tflru**********
created_at: "2019-12-04T08:45:31.131391Z"
name: timer
rule:
  timer:
    cron_expression: 5 12 * * ? *
    payload: <message>
    invoke_function_with_retry:
      function_id: d4eofc7n0m**********
      function_tag: $latest
      service_account_id: aje3932acd**********
      retry_settings:
        retry_attempts: "1"
        interval: 10s
      dead_letter_queue:
        queue-id: yrn:yc:ymq:ru-central1:aoek49ghmk**********:dlq
        service-account-id: aje3932acd**********
status: ACTIVE

Terraform allows you to quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. Configuration files store the infrastructure description in the HashiCorp Configuration Language (HCL). Terraform and its providers are distributed under the Business Source License.

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

If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.

If you don't have Terraform, install it and configure the Yandex Cloud provider.

To create a timer:

1. In the Terraform configuration file, describe the parameters of the resources you want to create:

   resource "yandex_function_trigger" "my_trigger" {
     name        = "<trigger_name>"
     description = "<trigger_description>"
     function {
       id                 = "<function_ID>"
       service_account_id = "<service_account_ID>"
       retry_attempts     = "<number_of_retry_invocation_attempts>"
       retry_interval     = "<interval_between_retry_attempts>"
     }
     timer {
       cron_expression = "<cron_expression>"
       payload         = "<message>"
     }
     dlq {
       queue_id           = "<dead_letter_queue_ID>"
       service_account_id = "<service_account_ID>"
     }
   }
   

   Where:

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

     • The name must be from 3 to 63 characters long.
     • It may contain lowercase Latin letters, numbers, and hyphens.
     • The first character must be a letter and the last character cannot be a hyphen.

   • description: Trigger description.

   • function: Function parameters:

     • id: Function ID.
     • service_account_id: ID of the service account with permissions to invoke the function.
     • retry_attempts: Number of invocation retries before the trigger moves a message to the dead-letter queue. This is an optional parameter. The values may range from 1 to 5. The default value is 1.
     • retry_interval: Time until another attempt is made to invoke the function if the current attempt fails. This is an optional parameter. The values may range from 10 to 60 seconds. The default value is 10 seconds.

   • timer: Trigger parameters:

     • cron_expression: Function invocation schedule specified as a cron expression.
     • payload: Message that will be sent to the function if the timer fires. The string length must not exceed 4,096 characters.
   • dlq: Dead-letter queue message parameters:
     • queue_id: Dead-letter queue ID. This is an optional parameter.
     • service_account_id: ID of the service account with write permissions to the dead-letter queue. This is an optional parameter.

   For more information about the yandex_function_trigger resource properties, see the provider documentation.

2. Create resources:

   1. In the terminal, change to the folder where you edited the configuration file.

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

      terraform validate
      

      If the configuration is correct, the following message is returned:

      Success! The configuration is valid.
      

   3. Run the command:

      terraform plan
      

      The terminal will display a list of resources with parameters. No changes are made at this step. If the configuration contains errors, Terraform will point them out.

   4. Apply the configuration changes:

      terraform apply
      

   5. Confirm the changes: type yes in the terminal and press Enter.

   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
   

To create a timer, use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call.