Idiomatic golang net/http gzip transparent compression, an updated version of https://gist.github.com/bryfry/09a650eb8aac0fb76c24

package main

import ( "net/http" "compress/gzip" "io/ioutil" "strings" "sync" "io" )

var gzPool = sync.Pool { New: func() interface{} { w := gzip.NewWriter(ioutil.Discard) return w }, }

type gzipResponseWriter struct { io.Writer http.ResponseWriter }

func (w *gzipResponseWriter) WriteHeader(status int) { w.Header().Del("Content-Length") w.ResponseWriter.WriteHeader(status) }

func (w *gzipResponseWriter) Write(b []byte) (int, error) { return w.Writer.Write(b) }

func Gzip(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") { next.ServeHTTP(w, r) return }

            w.Header().Set("Content-Encoding", "gzip")

            gz := gzPool.Get().(*gzip.Writer)
            defer gzPool.Put(gz)

            gz.Reset(w)
            defer gz.Close()

            next.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r)
    })

}