main.go

package main

import (
	"net/http"

	"github.com/gorilla/mux"
)

// example of a basic handler
func fooHandler(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("foo route\n"))
}

// example of a handler using vars
func barHandler(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("bar route got " + mux.Vars(r)["barID"] + "\n"))
}

// Dedicated handler to serve index.html to root route
func rootHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "./static/index.html")
}

func main() {
	r := mux.NewRouter()
	// these two are pretty standard
	r.HandleFunc("/foo", fooHandler).Methods("GET")
	r.HandleFunc("/bar/{barID}", barHandler).Methods("GET")
	// stripPrefix just removes the "static" prefix and passes what's left to http.FileServer. However, there is a special case for the
	// user requesting "index.htm[l]" where it will redirect to the root. See: https://golang.org/src/net/http/fs.go#L540
	// BUT, since http.StripPrefix has removed the static prefix, the redirect points back to root. But, our next route below serves
	// index.html statically from root. Since browsers follow permanent redirects automatically, this is transparent from a browser
	// perspective, but requires `curl -L` to properly follow with curl.
	r.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir("./static/"))))
	r.HandleFunc("/", rootHandler).Methods("GET")
	http.ListenAndServe(":8080", r)
}

shell output

$ curl localhost:8080/foo
foo route
$ curl localhost:8080/bar #will fail like expected
404 page not found
$ curl localhost:8080/bar/argument #fine with argument
bar route got argument
$ curl localhost:8080/static/file #doesn't exist
404 page not found
$ echo "static file" > static/file #create it
$ curl localhost:8080/static/file #again
static file
$ echo "hello index"> static/index.html #create the index
$ curl localhost:8080/ #root serves it just fine
hello index
$ curl localhost:8080/static/index.html #request it statically
$ # What? Nothing?
$ curl -v localhost:8080/static/index.html # Use -v (verbose) to see what's up
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /static/index.html HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 301 Moved Permanently
< Location: ./
< Date: Sun, 17 Feb 2019 18:59:15 GMT
< Content-Length: 0
<
* Connection #0 to host localhost left intact
$ # Aha, it's the redirect from fs.go
$ curl -L localhost:8080/static/index.html # Follow 301s like the browser
hello index
$ #Works!