es = Elasticsearch()
# get all indices name
indices_names = []
for elem in es.cat.indices(format="json"):
    indices_names.append( elem['index'] )
# get all fileds of index
dict_index_fields = {}
index = 'factiva.snapshot'
mapping = es.indices.get_mapping(index)
dict_index_fields[index] = []
for field in mapping[index]['mappings']['properties']:
    dict_index_fields[index].append(field)