Setting HTTP headers

Question

I'm trying to set a header in my Go web server. I'm using gorilla/mux and net/http packages.

I'd like to set Access-Control-Allow-Origin: * to allow cross domain AJAX.

Here's my Go code:

func saveHandler(w http.ResponseWriter, r *http.Request) {
// do some stuff with the request data
}

func main() {
    r := mux.NewRouter()
    r.HandleFunc("/save", saveHandler)
    http.Handle("/", r)
    http.ListenAndServe(":"+port, nil)
}

The net/http package has documentation describing sending http request headers as if it were a client - I'm not exactly sure how to set response headers?

Answer 1

Never mind, I figured it out - I used the Set() method on Header() (doh!)

My handler looks like this now:

func saveHandler(w http.ResponseWriter, r *http.Request) {
    // allow cross domain AJAX requests
    w.Header().Set("Access-Control-Allow-Origin", "*")
}

Maybe this will help someone as caffeine deprived as myself sometime :)

Answer 2

I know this is a different twist on the answer, but isn't this more of a concern for a web server? For example, nginx, could help.

The ngx_http_headers_module module allows adding the “Expires” and “Cache-Control” header fields, and arbitrary fields, to a response header

...

location ~ ^<REGXP MATCHING CORS ROUTES> {
    add_header Access-Control-Allow-Methods POST
    ...
}
...

Adding nginx in front of your go service in production seems wise. It provides a lot more feature for authorizing, logging,and modifying requests. Also, it gives the ability to control who has access to your service and not only that but one can specify different behavior for specific locations in your app, as demonstrated above.

I could go on about why to use a web server with your go api, but I think that's a topic for another discussion.