sessions are now tracked through cookies or query parameters.
This provides the ability to inspect sessions through logs, metrics and
API, allows more precise tracking of outbound bytes, decreases load on
external HTTP authentication URLs since they are now called once per
session and not once per request.
in API (/paths/list, /paths/get) and metrics (paths_bytes_sent), the
amount of sent bytes was increased even in case of writes to the
recorder and HLS muxer, which are not generating network traffic. This
fixes the issue.
