Support X-Forwarded-For in logging when behind a proxy

Hi,

By default, the logging in rest-server will always log the IP address of the connection, which in many cases will be the nearest proxy.

Adding support for the X-Forwarded-For headers will allow the logging to display the correct external IP.

Currently 'gorilla/handlers' is used for logging. 'gorilla/handlers' fully supports decoding the X-Forwarded-For headers if
you add the proxyHeaders middleware before the logging middleware.

I'm currently using the following patch (against master) to implemented the additional middleware:

diff --git mux.go mux.go
index 77fcdb4..294708e 100644
--- mux.go
+++ mux.go
@@ -21,6 +21,10 @@ func (s *Server) debugHandler(next http.Handler) http.Handler {
        })
 }

+func (s *Server) proxyHandler(next http.Handler) http.Handler {
+   return handlers.ProxyHeaders(next)
+}
+
 func (s *Server) logHandler(next http.Handler) http.Handler {
    var accessLog io.Writer

@@ -104,6 +108,9 @@ func NewHandler(server *Server) (http.Handler, error) {
    if server.Debug {
        handler = server.debugHandler(handler)
    }
+
+   handler = server.proxyHandler(handler)
+
    if server.Log != "" {
        handler = server.logHandler(handler)
    }

As a result, my logs now show the correct external IP, instead of the IP address of my proxy.

Any thoughts?

Start in mux.go, reading NewHandler and the existing debugHandler and logHandler middleware, then inspect how gorilla/handlers is used for logging. Verify the middleware ordering and confirm that logs show the external client IP from X-Forwarded-For when the server is behind a proxy.