I am trying to refer a variable in serverless.yml from another yml file,but when I run serverless deploy it does nothing.

**Serverless.yml

provider:
name: ${file(./constants.yml):name}
runtime: ${file(./constants.yml):runtime}
region: ${file(./constants.yml):region}**

I have refereed variable in provider.

constants .yml is in same folder as serverless.

D:\code\structuringserverless\serverless_sftp_workingcode>sls deploy
Serverless: Packaging service...
Serverless: Excluding development dependencies...

It does nothing after these two steps and just terminates without any error info.