fix: double compression.

middlewares/compress.go

@@ -1,13 +1,11 @@
 package middlewares
 
 import (
+	"compress/gzip"
 	"net/http"
 
 	"github.com/NYTimes/gziphandler"
-)
-
-const (
-	contentEncodingHeader = "Content-Encoding"
+	"github.com/containous/traefik/log"
 )
 
 // Compress is a middleware that allows redirection
@@ -15,17 +13,13 @@ type Compress struct{}
 
 // ServerHTTP is a function used by Negroni
 func (c *Compress) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
-	if isEncoded(r.Header) {
-		next.ServeHTTP(rw, r)
-	} else {
-		newGzipHandler := gziphandler.GzipHandler(next)
-		newGzipHandler.ServeHTTP(rw, r)
-	}
+	gzipHandler(next).ServeHTTP(rw, r)
 }
 
-func isEncoded(headers http.Header) bool {
-	header := headers.Get(contentEncodingHeader)
-	// According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding,
-	// content is not encoded if the header 'Content-Encoding' is empty or equals to 'identity'.
-	return header != "" && header != "identity"
+func gzipHandler(h http.Handler) http.Handler {
+	wrapper, err := gziphandler.NewGzipHandler(gzip.DefaultCompression, gziphandler.DefaultMinSize, &gziphandler.GzipResponseWriterWrapper{})
+	if err != nil {
+		log.Error(err)
+	}
+	return wrapper(h)
 }