SUDO:

[1] gitlabhq/doc/api at master · gitlabhq/gitlabhq (2015-03-06 10:45:19 +09:00 版) <https://github.com/gitlabhq/gitlabhq/tree/master/doc/api>

Example of a valid API with sudo request:
GET http://example.com/api/v3/projects?private_token=QVy1PB7sTxfy4pqfZM1U&sudo=username
GET http://example.com/api/v3/projects?private_token=QVy1PB7sTxfy4pqfZM1U&sudo=23
Example for a valid API request with sudo using curl and authentication via header:
curl --header "PRIVATE-TOKEN: QVy1PB7sTxfy4pqfZM1U" --header "SUDO: username" "http://example.com/api/v3/projects"
curl --header "PRIVATE-TOKEN: QVy1PB7sTxfy4pqfZM1U" --header "SUDO: 23" "http://example.com/api/v3/projects"