Are there any Global variables, different backends?

1

I have few basic questions about global variables and different backends as mentioned below, please provide your inputs on the same:

  1. Is there any way I can use global or environment variables in the service/route/plugin ? For example, backend hostname on dev env is dev-mysite.com and for QA and prod it is qa-mysite.com and prod-mysite.com
    So when configuring service I will simply add env or global variable outside of service/route/plugin and call it in the host section of service. so my hostname will be dynamically populated.
    This is useful when you promote your code from lower env to higher.

  2. Based on the request values, I want to route the request to different backends. Is there any way that I can define different backend for the same request and invoke the backend url based on the input request param values?

  3. Are there default built in service/route/plugin variables that will be assigned with values during or post execution of service/route/plugin ? And the same we can use in further processing of the request in the flow ?

2

Looks like none of above features available in Kong