TUN-8728: implement diag/tunnel endpoint

## Summary
The new endpoint returns the current information to be used when calling the diagnostic procedure.
This also adds:
- add indexed connection info and method to extract active connections from connTracker
- add edge address to Event struct and conn tracker
- remove unnecessary event send
- add tunnel configuration handler
- adjust cmd and metrics to create diagnostic server

Closes TUN-8728

metrics/metrics.go

@@ -94,6 +94,7 @@ func newMetricsHandler(
 		})
 	}
 
+	router.HandleFunc("/diag/tunnel", config.DiagnosticHandler.TunnelStateHandler)
 	router.HandleFunc("/diag/system", config.DiagnosticHandler.SystemHandler)
 
 	return router

metrics/readiness.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/google/uuid"
 
-	conn "github.com/cloudflare/cloudflared/connection"
 	"github.com/cloudflare/cloudflared/tunnelstate"
 )
 
@@ -28,10 +27,6 @@ func NewReadyServer(
 	}
 }
 
-func (rs *ReadyServer) OnTunnelEvent(c conn.Event) {
-	rs.tracker.OnTunnelEvent(c)
-}
-
 type body struct {
 	Status           int       `json:"status"`
 	ReadyConnections uint      `json:"readyConnections"`

metrics/readiness_test.go

@@ -44,7 +44,7 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.Zero(t, readyConnections)
 
 	// one connected => ok
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     1,
 		EventType: connection.Connected,
 	})
@@ -53,7 +53,7 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.EqualValues(t, 1, readyConnections)
 
 	// another connected => still ok
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     2,
 		EventType: connection.Connected,
 	})
@@ -62,7 +62,7 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.EqualValues(t, 2, readyConnections)
 
 	// one reconnecting => still ok
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     2,
 		EventType: connection.Reconnecting,
 	})
@@ -71,7 +71,7 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.EqualValues(t, 1, readyConnections)
 
 	// Regression test for TUN-3777
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     1,
 		EventType: connection.RegisteringTunnel,
 	})
@@ -80,14 +80,14 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.Zero(t, readyConnections)
 
 	// other connected then unregistered  => not ok
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     1,
 		EventType: connection.Connected,
 	})
 	code, readyConnections = mockRequest(t, rs)
 	assert.EqualValues(t, http.StatusOK, code)
 	assert.EqualValues(t, 1, readyConnections)
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     1,
 		EventType: connection.Unregistering,
 	})
@@ -96,7 +96,7 @@ func TestReadinessEventHandling(t *testing.T) {
 	assert.Zero(t, readyConnections)
 
 	// other disconnected => not ok
-	rs.OnTunnelEvent(connection.Event{
+	tracker.OnTunnelEvent(connection.Event{
 		Index:     1,
 		EventType: connection.Disconnected,
 	})