const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({action: 'provision', params: {}})
};

fetch('https://api.example.com/v1/regions/{region}/infrastructure/servers/{id}/actions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "success": true,
  "data": {
    "action": "<string>",
    "serverId": "<string>",
    "status": "accepted",
    "reason": "<string>"
  }
}