func (s *EnvoyApi) optionsHandler(response http.ResponseWriter, req *http.Request) {
	response.Header().Set("Access-Control-Allow-Origin", "*")
	response.Header().Set("Access-Control-Allow-Methods", "GET")
	return
}
optionsHandler sends CORS headers
package envoyhttp
import (
	"encoding/json"
	"fmt"
	"net/http"
	_ "net/http/pprof"
	"time"
	"github.com/gorilla/mux"
	"github.com/pquerna/ffjson/ffjson"
	log "github.com/sirupsen/logrus"
)
type EnvoyApi struct {
	registrar *Registrar
}
func NewEnvoyApi(registrar *Registrar) *EnvoyApi {
	return &EnvoyApi{
		registrar: registrar,
	}
}