Swathy,
When you create the VDB, it returns the container name in the response. If you need to grab the container name for a VDB at a different time, like in another job, then you would get the list of VDB's and use logic to grab the one for your name. In our github repo, you can leverage the find_obj_by_name class. For example:
https://github.com/CloudSurgeon/delphixpy-examples/blob/master/dx_provision_vdb.py#L398Then your container reference is the reference of that object.
So in the example at that link, the following would print the container id:
print vdb_obj.reference