TUN-2846: Trigger debug reconnects from stdin commands, not SIGUSR1

cmd/cloudflared/tunnel/cmd.go

@@ -1,18 +1,17 @@
 package tunnel
 
 import (
+	"bufio"
 	"context"
 	"fmt"
 	"io/ioutil"
 	"net"
 	"net/url"
 	"os"
-	ossig "os/signal"
 	"reflect"
 	"runtime"
 	"runtime/trace"
 	"sync"
-	"syscall"
 	"time"
 
 	"github.com/cloudflare/cloudflared/awsuploader"
@@ -401,9 +400,11 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
 		return err
 	}
 
-	// When the user sends SIGUSR1, disconnect all connections.
-	reconnectCh := make(chan os.Signal, 1)
-	ossig.Notify(reconnectCh, syscall.SIGUSR1)
+	reconnectCh := make(chan struct{}, 1)
+	if c.IsSet("stdin-control") {
+		logger.Warn("Enabling control through stdin")
+		go stdinControl(reconnectCh)
+	}
 
 	wg.Add(1)
 	go func() {
@@ -1066,5 +1067,28 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
 			EnvVars: []string{"HOST_KEY_PATH"},
 			Hidden:  true,
 		}),
+		altsrc.NewBoolFlag(&cli.BoolFlag{
+			Name:    "stdin-control",
+			Usage:   "Control the process using commands sent through stdin",
+			EnvVars: []string{"STDIN-CONTROL"},
+			Hidden:  true,
+			Value:   false,
+		}),
+	}
+}
+
+func stdinControl(reconnectCh chan struct{}) {
+	for {
+		scanner := bufio.NewScanner(os.Stdin)
+		for scanner.Scan() {
+			command := scanner.Text()
+
+			switch command {
+			case "reconnect":
+				reconnectCh <- struct{}{}
+			default:
+				logger.Warn("Unknown command: ", command)
+			}
+		}
 	}
 }

origin/supervisor.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"net"
-	"os"
 	"sync"
 	"time"
 
@@ -106,7 +105,7 @@ func NewSupervisor(config *TunnelConfig, u uuid.UUID) (*Supervisor, error) {
 	}, nil
 }
 
-func (s *Supervisor) Run(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan os.Signal) error {
+func (s *Supervisor) Run(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan struct{}) error {
 	logger := s.config.Logger
 	if err := s.initialize(ctx, connectedSignal, reconnectCh); err != nil {
 		return err
@@ -192,7 +191,7 @@ func (s *Supervisor) Run(ctx context.Context, connectedSignal *signal.Signal, re
 }
 
 // Returns nil if initialization succeeded, else the initialization error.
-func (s *Supervisor) initialize(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan os.Signal) error {
+func (s *Supervisor) initialize(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan struct{}) error {
 	logger := s.logger
 
 	s.lastResolve = time.Now()
@@ -222,7 +221,7 @@ func (s *Supervisor) initialize(ctx context.Context, connectedSignal *signal.Sig
 
 // startTunnel starts the first tunnel connection. The resulting error will be sent on
 // s.tunnelErrors. It will send a signal via connectedSignal if registration succeed
-func (s *Supervisor) startFirstTunnel(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan os.Signal) {
+func (s *Supervisor) startFirstTunnel(ctx context.Context, connectedSignal *signal.Signal, reconnectCh chan struct{}) {
 	var (
 		addr *net.TCPAddr
 		err  error
@@ -266,7 +265,7 @@ func (s *Supervisor) startFirstTunnel(ctx context.Context, connectedSignal *sign
 
 // startTunnel starts a new tunnel connection. The resulting error will be sent on
 // s.tunnelErrors.
-func (s *Supervisor) startTunnel(ctx context.Context, index int, connectedSignal *signal.Signal, reconnectCh chan os.Signal) {
+func (s *Supervisor) startTunnel(ctx context.Context, index int, connectedSignal *signal.Signal, reconnectCh chan struct{}) {
 	var (
 		addr *net.TCPAddr
 		err  error

origin/tunnel.go

@@ -9,7 +9,6 @@ import (
 	"net"
 	"net/http"
 	"net/url"
-	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -170,7 +169,7 @@ func (c *TunnelConfig) RegistrationOptions(connectionID uint8, OriginLocalIP str
 	}
 }
 
-func StartTunnelDaemon(ctx context.Context, config *TunnelConfig, connectedSignal *signal.Signal, cloudflaredID uuid.UUID, reconnectCh chan os.Signal) error {
+func StartTunnelDaemon(ctx context.Context, config *TunnelConfig, connectedSignal *signal.Signal, cloudflaredID uuid.UUID, reconnectCh chan struct{}) error {
 	s, err := NewSupervisor(config, cloudflaredID)
 	if err != nil {
 		return err
@@ -186,7 +185,7 @@ func ServeTunnelLoop(ctx context.Context,
 	connectedSignal *signal.Signal,
 	u uuid.UUID,
 	bufferPool *buffer.Pool,
-	reconnectCh chan os.Signal,
+	reconnectCh chan struct{},
 ) error {
 	connectionLogger := config.Logger.WithField("connectionID", connectionID)
 	config.Metrics.incrementHaConnections()
@@ -235,7 +234,7 @@ func ServeTunnel(
 	backoff *BackoffHandler,
 	u uuid.UUID,
 	bufferPool *buffer.Pool,
-	reconnectCh chan os.Signal,
+	reconnectCh chan struct{},
 ) (err error, recoverable bool) {
 	// Treat panics as recoverable errors
 	defer func() {