It is straightforward to serve static pages with Go or config file on App Engine, but how to serve static pages on App Engine with Go?

I got the following error when I tried to customize the 404 page with Go:

No such file or directory

The solution turns out to be simple: do not do both.

The file will not be accessible to Go if there is already a rule for it in config.yaml. Remove the rule from config.yaml and the file will be available to Go again (source: google-appengine-go).

Here is an exmaple to serve a custom 404 not found page:

func serve404(w http.ResponseWriter, r *http.Request) {
	f, err := http.Dir("public").Open("404.html")
	if err != nil {
		serveError(w, r, err)
	defer f.Close()
	io.Copy(w, f)