addons: usercmds: adding environment variables passed by the ifupdown2 to user scripts

Ticket: None
Reviewed By: Roopa
Testing Done: with a dummy script I printed the value passed by ifupdown
After the changes I did the same with ifupdown2 and checksd if the values
matched correctly.

This issue was reported on the github repository.

Signed-off-by: Julien Fortin <julien@cumulusnetworks.com>

addons/usercmds.py

@@ -4,6 +4,7 @@
 # Author: Roopa Prabhu, roopa@cumulusnetworks.com
 #
 
+import os
 import ifupdownaddons
 
 from ifupdown.utils import utils
@@ -36,6 +37,10 @@ class usercmds(ifupdownaddons.modulebase.moduleBase):
     def _run_command(self, ifaceobj, op):
         cmd_list = ifaceobj.get_attr_value(op)
         if cmd_list:
+            os.environ['IFACE'] = ifaceobj.name
+            os.environ['LOGICAL'] = ifaceobj.name
+            os.environ['METHOD'] = ifaceobj.addr_method
+            os.environ['ADDRFAM'] = ifaceobj.addr_family
             for cmd in cmd_list:
                 try:
                     utils.exec_user_command(cmd)