Golang Gorilla mux with http.FileServer returning 404

StackOverflow https://stackoverflow.com/questions/21234639

  •  30-09-2022
  •  | 
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Pregunta

The problem I'm seeing is that I'm trying to use the http.FileServer with the Gorilla mux Router.Handle function.

This doesn't work (the image returns a 404)..

myRouter := mux.NewRouter()
myRouter.Handle("/images/", http.StripPrefix("/images/", http.FileServer(http.Dir(HomeFolder + "images/"))))

this works (the image is shown ok)..

http.Handle("/images/", http.StripPrefix("/images/", http.FileServer(http.Dir(HomeFolder + "images/"))))

Simple go web server program below, showing the problem...

package main

import (
    "fmt"
    "net/http"
    "io"
    "log"
    "github.com/gorilla/mux"
)

const (
    HomeFolder = "/root/test/"
)

func HomeHandler(w http.ResponseWriter, req *http.Request) {
    io.WriteString(w, htmlContents)
}

func main() {

    myRouter := mux.NewRouter()
    myRouter.HandleFunc("/", HomeHandler)
    //
    // The next line, the image route handler results in 
    // the test.png image returning a 404.
    // myRouter.Handle("/images/", http.StripPrefix("/images/", http.FileServer(http.Dir(HomeFolder + "images/"))))
    //
    myRouter.Host("mydomain.com")
    http.Handle("/", myRouter)

    // This method of setting the image route handler works fine.
    // test.png is shown ok.
    http.Handle("/images/", http.StripPrefix("/images/", http.FileServer(http.Dir(HomeFolder + "images/"))))

    // HTTP - port 80
    err := http.ListenAndServe(":80", nil)

    if err != nil {
        log.Fatal("ListenAndServe: ", err)
        fmt.Printf("ListenAndServe:%s\n", err.Error())
    }
}

const htmlContents = `<!DOCTYPE HTML>
<html lang="en">
  <head>
    <title>Test page</title>
    <meta charset = "UTF-8" />
  </head>
  <body>
    <p align="center">
        <img src="/images/test.png" height="640" width="480">
    </p>
  </body>
</html>
`
¿Fue útil?

Solución

I posted this on golang-nuts discussion group and got this solution from Toni Cárdenas ...

The standard net/http ServeMux (which is the standard handler you are using when you use http.Handle) and the mux Router have different ways of matching an address.

See the differences between http://golang.org/pkg/net/http/#ServeMux and http://godoc.org/github.com/gorilla/mux.

So basically, http.Handle('/images/', ...) matches '/images/whatever', while myRouter.Handle('/images/', ...) only matches '/images/', and if you want to handle '/images/whatever', you have to ...

Option 1 - Use a regular expression match in your router

myRouter.Handle("/images/{rest}",
     http.StripPrefix("/images/", http.FileServer(http.Dir(HomeFolder + "images/"))))

Option 2 - Use the PathPrefix method on your router:

myRouter.PathPrefix("/images/").Handler(http.StripPrefix("/images/", 
     http.FileServer(http.Dir(HomeFolder + "images/"))))

Otros consejos

As of May 2015 gorilla/mux package still have no version releases. But problem is different now. It is not that myRouter.Handle does not match url and needs regexp, it does! But http.FileServer requires prefix to be removed from url. Below example works fine.

ui := http.FileServer(http.Dir("ui"))
myRouter.Handle("/ui/", http.StripPrefix("/ui/", ui))

Note, there is no /ui/{rest} in abowe example. You may also wrap http.FileServer into logger gorilla/handler and see request to coming to FileServer and response 404 going out.

ui := handlers.CombinedLoggingHandler(os.Stderr,http.FileServer(http.Dir("ui"))
myRouter.Handle("/ui/", ui) // getting 404
// works with strip: myRouter.Handle("/ui/", http.StripPrefix("/ui/", ui))
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