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, 14 Jun 2018 08:35:18 GMT
Server: Python/3.5 GNS3/2.1.8dev1
X-Route: /v2/settings

{
    "modification_uuid": "c8a68ba6-b99c-491d-b12b-9ff4089f04ac",
    "test": true
}