mirror

mirror copies the data clients send to shadow servers and continues the chain. Replies of the shadow servers are discarded, so they never reach the client. Use it to try a new version of a service with real traffic.

server:
  tcp:
    middlewares:
      shadow:
        mirror:
          servers:
            - address: 10.0.0.50:6379
              percent: 10
      backend:
        redirect:
          address: 10.0.0.1:6379
    routers:
      redis:
        entrypoints: [redis]
        middlewares: [shadow, backend]

Field	Default	Description
servers[].address		Shadow server host:port.
servers[].percent	100	Percent of connections to mirror.
dial_timeout	2s	Dial timeout of shadow servers.
buffer	1048576	Bytes queued per shadow connection.

Each mirrored client connection opens its own connection to the shadow server. Shadow servers never slow the real connection down: if one cannot be reached or reads slower than the client sends and its buffer fills up, its copy stops for that connection. Mirroring is best effort; errors are only logged at debug level.

Only data sent by the client is mirrored. Place mirror before tls_terminate to mirror encrypted data, after it to mirror plain data, and before the terminal middleware.