Serving up static files from Go / Gorilla mux

I've been playing with Go lately, just serving up a non-trivial API to kick the tires a bit.

One of the things I wanted to do was use the Swagger (https://helloreverb.com/developers/swagger) framework to document that API (I've done this before in Ruby with grape and it was a breeze).  (BTW - it was considerably more tedious to write the specification (even using the awesome https://github.com/wordnik/swagger-editor) but that's a different post...)

I needed to host the swagger-ui files (which they helpfully bundle into a 'dist' folder) and serve them up from my Go application.  The directory structure looked like this:

├── server.go

├── swagger-ui/

│   ├── css/

│   ├── images/

│   ├── index.html

│   ├── lib/

It ended up being fairly trivial to serve static files but took a little experimentation to get the Gorilla mux piece working correctly.  Here's what I ended up doing, inside 'server.go'

func main() {
router = mux.NewRouter()
router.HandleFunc("/", indexHandler)
router.HandleFunc("/api-docs", apiDocHandler)
router.PathPrefix("/swagger-ui/").Handler(http.StripPrefix("/swagger-ui/", http.FileServer(http.Dir("./swagger-ui/"))))
http.Handle("/", router)
err := http.ListenAndServeTLS(":8443", "cert.pem", "key.pem", router)
if err != nil {
log.Fatalln(err)
}
}

Important parts to realize:
1) you should use the PathPrefix so that the mux picks up everything inside that folder
2) you need to strip out the path prefix so that your files are served up from the correct directory, otherwise you'll end up making requests for /swagger-ui/swagger-ui/ which won't work.