How do you serve a static html file using a go web server?

NOT a FTP server: That is something different than what I intended, which would be to serve the index.html homepage, like a normal web server would. Like, when I go to mydomain.com in my browser, I want index.html rendered.

That is mainly what "Writing Web Applications" describes, and what a project like hugo (static html site generator) does.

It is about reading a file, and responsing with a ContentType "text/html":

func (server *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    err := server.renderFile(w, r.URL.Path)
    if err != nil {
        w.Header().Set("Content-Type", "text/html; charset=utf-8")
        w.WriteHeader(http.StatusNotFound)
        server.fn404(w, r)
    }
}

with renderFile() essentially reading and setting the right type:

 file, err = ioutil.ReadFile(server.MediaPath + filename)
 if ext != "" {
    w.Header().Set("Content-Type", mime.TypeByExtension(ext))
 }

If you only want to serve 1 file and not a full directory, you can use http.ServeFile

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    http.ServeFile(w, r, "index.html")
})

I prefer using http.ServeFile for this over http.FileServer. I wanted directory browsing disabled, a proper 404 if files are missing and an easy way to special case the index file. This way, you can just drop the built binary into a folder and it will serve everything relative to that binary. Of course, you can use strings.Replace on p if you have the files stored in another directory.


func main() {
    fmt.Println("Now Listening on 80")
    http.HandleFunc("/", serveFiles)
    log.Fatal(http.ListenAndServe(":80", nil))
}

func serveFiles(w http.ResponseWriter, r *http.Request) {
    fmt.Println(r.URL.Path)
    p := "." + r.URL.Path
    if p == "./" {
        p = "./static/index.html"
    }
    http.ServeFile(w, r, p)
}

That task is very easy with Golang net/http package.

All You need to do is:

package main

import (
        "net/http"
)

func main() {
        http.Handle("/", http.FileServer(http.Dir("./static")))
        http.ListenAndServe(":3000", nil)
}

assuming that static files are in folder named static in the root directory of the project.

If it's in folder static, you'll have index.html file calling http://localhost:3000/ which will result in rendering that index file instead of listing all the files availible.

Additionally, calling any other file in that folder (for example http://localhost:3000/clients.html) will show that file, properly rendered by the browser (at least Chrome, Firefox and Safari :))

UPDATE: serving files from url different than "/"

If You want to serve files, say from folder ./public under url: localhost:3000/static You have to use additional function: func StripPrefix(prefix string, h Handler) Handler like this:

package main

import (
        "net/http"
)

func main() {
        http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("./public"))))
        http.ListenAndServe(":3000", nil)
}

Thanks to that, all your files from ./public are avalible under localhost:3000/static

Without http.StripPrefix function, if you would try to access file localhost:3000/static/test.html, the server would look for it in ./public/static/test.html

This is because the server treats the whole URI as a relative path to the file.

Fortunately, it's easily solved with the built-in function.

Tags:

Go

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