// Server push lets the server preemptively "push" website assets // to the client without the user having explicitly asked for them. // When used with care, we can send what we know the user is going // to need for the page they're requesting. package main import ( "net/http" "github.com/kataras/iris/v12" ) func main() { app := iris.New() app.Get("/", pushHandler) app.Get("/main.js", simpleAssetHandler) app.Run(iris.TLS("127.0.0.1:443", "mycert.crt", "mykey.key")) // $ openssl req -new -newkey rsa:4096 -x509 -sha256 \ // -days 365 -nodes -out mycert.crt -keyout mykey.key } func pushHandler(ctx iris.Context) { // The target must either be an absolute path (like "/path") or an absolute // URL that contains a valid host and the same scheme as the parent request. // If the target is a path, it will inherit the scheme and host of the // parent request. target := "/main.js" if pusher, ok := ctx.ResponseWriter().Naive().(http.Pusher); ok { err := pusher.Push(target, nil) if err != nil { if err == iris.ErrPushNotSupported { ctx.StopWithText(iris.StatusHTTPVersionNotSupported, "HTTP/2 push not supported.") } else { ctx.StopWithError(iris.StatusInternalServerError, err) } return } } ctx.HTML(``, target) } func simpleAssetHandler(ctx iris.Context) { ctx.ServeFile("./public/main.js") }