openapi: 3.0.0
info:
  title: How server URLs can be templated
  version: 1.0.0

servers:
- url: https://{tenant}.acme.com/api/{version}
  variables:
    tenant:
      default: sample  #default is a required field
    version:
      default: v2
      enum:
       - v2
       - 3
paths: {}