gistfile1.py

    def add_iface_to_netns(if_name, ns_name):
        #
        # init IPDB and netns
        ipdb = IPDB()
        netns = None
        #
        # try to perform the operation
        try:
            # NetNS() constructor also can raise exceptions,
            # so put it under try/catch
            #
            netns = NetNS(ns_name)
            #
            # the code below can raise exceptions from IPDB
            #
            iface = ipdb.interfaces[if_name]
            with iface as veth:
                veth.net_ns_fd = netns.netns
        except Exception as e:
            print(e)
        finally:
            print("Release...")
            #
            # We should clean up ALL we spawned.
            #
            # The order doesn't matter, but matters did we close
            # all IPDB and NetNS instances, or not:
            #
            ipdb.release()
            #
            # Close NetNS only if it was instantiated
            #
            if netns is not None:
                netns.close()