gns3-server/docs/api/examples/controller_post_settings.txt

curl -i -X POST 'http://localhost:3080/v2/settings' -d '{"test": true}'

POST /v2/settings HTTP/1.1
{
    "test": true
}


HTTP/1.1 201
Connection: close
Content-Length: 85
Content-Type: application/json
Date: Thu, 16 Aug 2018 14:23:27 GMT
Server: Python/3.5 GNS3/2.2.0dev2
X-Route: /v2/settings

{
    "modification_uuid": "b8acf218-c6e4-4a4f-992f-b57b286897d9",
    "test": true
}