layer_properties(layer_id, 'attribution')

iface.activeLayer().id()

# Be sure to import iface from qgis.utils

from qgis.core import *
from qgis.gui import *
from qgis.utils import iface

@qgsfunction(args='auto', group='Custom')
def get_layer_name(feature, parent):
    return qgis.utils.iface.activeLayer().name()