AUTH-2587 add config watcher and reload logic for access client forwarder

cmd/cloudflared/config/model.go

@@ -0,0 +1,37 @@
+package config
+
+import (
+	"crypto/md5"
+	"fmt"
+	"io"
+)
+
+// Forwarder represents a client side listener to forward traffic to the edge
+type Forwarder struct {
+	URL      string `json:"url"`
+	Listener string `json:"listener"`
+}
+
+// Tunnel represents a tunnel that should be started
+type Tunnel struct {
+	URL          string `json:"url"`
+	Origin       string `json:"origin"`
+	ProtocolType string `json:"type"`
+}
+
+// Root is the base options to configure the service
+type Root struct {
+	OrgKey          string      `json:"org_key"`
+	ConfigType      string      `json:"type"`
+	CheckinInterval int         `json:"checkin_interval"`
+	Forwarders      []Forwarder `json:"forwarders,omitempty"`
+	Tunnels         []Tunnel    `json:"tunnels,omitempty"`
+}
+
+// Hash returns the computed values to see if the forwarder values change
+func (f *Forwarder) Hash() string {
+	h := md5.New()
+	io.WriteString(h, f.URL)
+	io.WriteString(h, f.Listener)
+	return fmt.Sprintf("%x", h.Sum(nil))
+}