Nested ServeMux always returns "301 Moved Permanently"

Edit: to make testing easier in Firefox, I disabled caching.. otherwise I would have to manually clear cache to get accurate results. I did not seem to have this same issue when using Chrome, though.

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Keep in mind I am new to Go but this issue was driving me crazy... I was experiencing the same exact behavior that you are (obviously)..

It would seem Go/http is picky about how patterns are formatted..

I messed with this for about an hour and was finally able to get a working example using the following code:

// Working Code
package main

import "net/http"

func main() {
    root := http.NewServeMux()
    api := http.NewServeMux()

    api.HandleFunc("/ping", myHandlerFunc)

    root.Handle("/api/", http.StripPrefix("/api", api))

    http.ListenAndServe(":8080", root)
}

func myHandlerFunc(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("pong\n"))
}

I tried as many different configurations as you can imagine (as far as / forward slashes are concerned) and the above code was the only way I could get it to work..

Specifically referring to:

// Leading forward slash on /ping
api.HandleFunc("/ping", myHandlerFunc)

// The first /api/ is surrounded in forward slashes,
// the second /api only contains a leading forward slash
root.Handle("/api/", http.StripPrefix("/api", api))

Changing the code to this causes 404's...

// DOES NOT WORK!!
package main

import "net/http"

func main() {
    root := http.NewServeMux()
    api := http.NewServeMux()

    api.HandleFunc("/ping", myHandlerFunc)

    root.Handle("/api", http.StripPrefix("/api", api))

    http.ListenAndServe(":8080", root)
}

func myHandlerFunc(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("pong\n"))
}

I hope this helps in some way! Cheers