Serving gzipped content for Go

I'm starting to write server-side applications in Go. I'd like to use the Accept-Encoding request header to determine whether to compress the response entity using GZIP. I had hoped to find a way to do this directly using the http.Serve or http.ServeFile methods.

This is quite a general requirement; did I miss something or do I need to roll my own solution?

The New York Times have released their gzip middleware package for Go.

You just pass your http.HandlerFunc through their GzipHandler and you're done. It looks like this:

package main

import (
    "io"
    "net/http"
    "github.com/nytimes/gziphandler"
)

func main() {
    withoutGz := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Content-Type", "text/plain")
        io.WriteString(w, "Hello, World")
    })

    withGz := gziphandler.GzipHandler(withoutGz)

    http.Handle("/", withGz)
    http.ListenAndServe("0.0.0.0:8000", nil)
}

There is no “out of the box” support for gzip-compressed HTTP responses yet. But adding it is pretty trivial. Have a look at

https://gist.github.com/the42/1956518

also

https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/cgUp8_ATNtc

For the sake of completeness, I eventually answered my own question with a handler that is simple and specialises in solving this issue.

• https://pkg.go.dev/github.com/rickb777/servefiles?tab=doc
• https://github.com/rickb777/servefiles

This serves static files from a Go http server, including the asked-for performance-enhancing features. It is based on the standard net/http ServeFiles, with gzip/brotli and cache performance enhancements.

There is yet another "out of the box" middleware now, supporting net/http and Gin:

https://github.com/nanmu42/gzip

net/http example:

import github.com/nanmu42/gzip

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		writeString(w, fmt.Sprintf("This content is compressed: l%sng!", strings.Repeat("o", 1000)))
	})

    // wrap http.Handler using default settings
	log.Println(http.ListenAndServe(fmt.Sprintf(":%d", 3001), gzip.DefaultHandler().WrapHandler(mux)))
}

func writeString(w http.ResponseWriter, payload string) {
	w.Header().Set("Content-Type", "text/plain; charset=utf8")
	_, _ = io.WriteString(w, payload+"\n")
}

Gin example:

import github.com/nanmu42/gzip

func main() {
	g := gin.Default()

    // use default settings
	g.Use(gzip.DefaultHandler().Gin)

	g.GET("/", func(c *gin.Context) {
		c.JSON(http.StatusOK, map[string]interface{}{
			"code": 0,
			"msg":  "hello",
			"data": fmt.Sprintf("l%sng!", strings.Repeat("o", 1000)),
		})
	})

	log.Println(g.Run(fmt.Sprintf(":%d", 3000)))
}