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, 29 Jun 2017 15:08:08 GMT
Server: Python/3.6 GNS3/2.1.0dev1
X-Route: /v2/settings

{
    "modification_uuid": "8c59037b-2cc6-4d4d-be9b-e072fb0eee2a",
    "test": true
}