getting error: "cannot create storage without CA URL"

caddy-test.go

package main

import (
	"github.com/mholt/caddy"

	// plug in the server
	_ "github.com/mholt/caddy/caddyhttp"

	"log"
)

func main() {
	caddy.AppName = "Sprocket"
	caddy.AppVersion = "1.2.3"

	// pass in the name of the server type this Caddyfile is for (like "http")
	caddyfile, err := caddy.LoadCaddyfile("http")
	if err != nil {
		log.Fatal(err)
	}

	instance, err := caddy.Start(caddyfile)
	if err != nil {
		log.Fatal(err)
	}

	// Start() only blocks until the servers have started.
	// Wait() blocks until the servers have stopped.
	instance.Wait()
}