Snipet of https://github.com/hassaku63/sls-env-example

sls-env-example.serverless.provider.yml

provider:
  name: aws
  runtime: python3.8
  profile: ${opt:profile, default}
  stage: ${opt:stage, dev}
  region: ${opt:region, us-east-1}
  timeout: 30
  environment:
    # To tell lambda function to AWS AccountId by use pseudo-parameters plugin.
    # AccountId is used to construct SQS Queue URL
    AWS_ACCOUNT_ID: '#{AWS::AccountId}'
    # MY_QUEUE_NAME is used to construct Queue URL in lambda.
    # And also convenient to reference resource ARN in IAM Policy statement
    MY_QUEUE_NAME: ${self:service}-my-queue-${self:provider.stage}