My docker compose

    version: '3.9'
    services:
     test:
       secrets:
         - source: impKey
        
    secrets:
      impKey:
        file: somePath/cred.txt

Works fine, when I have a cred file in path. I am looking to dynamically inject the value as secrets.

Other option->

secret:
    impKey:
       extend: True

Problem is, we have to create secret separately. (Not part of stack ).
Is there any other option?