log

log writes one log line when a connection closes, with the client and local address, duration and transferred bytes.

server:
  tcp:
    middlewares:
      access:
        log:
          level: info

Field	Default	Description
level	info	Log level: debug, info, warn or error. Failed connections are logged at least at warn.

Place it first in the router to include every connection. Bytes are counted at the position of the middleware, so before tls_terminate they include TLS overhead.