HTTP Header Support
In addition, to injecting the Forwarded and X-Real-Ip headers the
X-Forwarded-For, X-Forwarded-Port and X-Forwarded-Proto headers are added
to HTTP(S) and Websocket requests. Custom headers for the ip address and
protocol can be configured with the proxy.header.clientip, proxy.header.tls
and proxy.header.tls.value options.
Since version 1.5.3 fabio also sets the X-Forwarded-Host header.