Ah, the root cause is the evil "," in the following function NetPollster.make_vnic_counter():
resource_metadata['instance_type'] = \ instance.flavor['id'] if instance.flavor else None,
The trailing ',' change it from a unicode type to tuple type.
However, the limitation Doug mentioned in comment #2 is still valid.
Ah, the root cause is the evil "," in the following function NetPollster. make_vnic_ counter( ):
resource_ metadata[ 'instance_ type'] = \
instance. flavor[ 'id'] if instance.flavor else None,
The trailing ',' change it from a unicode type to tuple type.
However, the limitation Doug mentioned in comment #2 is still valid.