Standard irule that can be used for multiple urls

Hello Notanf5engineer 
I've built the following bsed on given examples, it might still be incomplete and not cover all of your scenarios but it might be a good starting point 

Let me know if I can help you with improving it 

Edit: fixed syntax, tested irule 

CA

when HTTP_REQUEST {

  #If you have multiple SNI that resolve to this VS, consider enabling row below
#  if {[string tolower [HTTP::host]] ne "abcd.com"}{ return }

  switch -glob [HTTP::uri] {
    /app1/* {
	  # this will match everything starting with /app1/* (case sensitive) , remove "app1" folder and redirect 
	  # ex. /app1/test to /test 
	  # client will see the redirect

	  set uri [string trimleft [HTTP::uri] /app1]
      HTTP::redirect "http://app1.internaldomain.com/$uri"
    }
    /app2/API/hello {
	  # this is an exact match on a specific URI (case sensitive) 
	  # URI is not trimmed and is passed as-is 
	  # client will see the redirect
	  
	  HTTP::redirect "http://api2.internaldomain.com/[HTTP::uri]"
	}
	default { 
      # this matches everything not specified before
	  # HTTP::respond 401 
	}
  }
}

Notanf5engineer Is this a redirect that needs to occur or does the client need to see the original URL and the server needs to see the modified one?

Thank you CA_Valli.
I think this works when we are hardcoding the app1 in the condition.

I was wondering if this irule can be agnostic in a way it can be used for any number of Virtual servers.

Example:

testurl.externaldomain.com/app1/api/hello

testurl.extenaldomain.com/app2/api/bye

testdifferenturl.externaldomain.com/app4/api/test/*/*

so all these urls will have one virutal server which should have a common generalized irule.

testurl.externaldomain.com/app1dev/api/hello  - it would be a redirect the customer still sees the same url in the browser.

set hostname: app1dev.internaldomain.com/api/hello

set pool : testurl.externaldomain.com_app1dev

testurl.externaldomain.com/app1qa/api/getemployeedetails  - it would be a redirect the customer still sees the same url in the browser.

set hostname: app1qa.internaldomain.com/api/getemployeedetails

set pool : testurl.externaldomain.com_app1qa

the way we formulated the url is 

externaldomain/appname/whateverapitheappsupports.
appname needs to be appended with internaldomain and the whateverapitheappsupports need to the URI.
whateverapitheappsupports - this can be just /api/hello or /api/employee/1234 or /swagger anything that comes after the app name.


Please let me know if the above example is clear or if i am not explaining it properly.