serverless/docs/guides/variables/aws.md

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Reference AWS-specific variables

You can reference AWS-specific values as the source of your variables. Those values are exposed via the Serverless Variables system through the {aws:} variable prefix.

The following variables are available:

accountId

Account ID of you AWS Account, based on the AWS Credentials that you have configured.

service: new-service
provider:
  name: aws

functions:
  func1:
    name: function-1
    handler: handler.func1
    environment:
      ACCOUNT_ID: ${aws:accountId}

region

The region used by the Serverless CLI. The ${aws:region} variable is a shortcut for ${opt:region, self:provider.region, "us-east-1"}.