cmd/dlv: Add ability to connect to headless server

Fixes #201. Use to connect to a running headless server

cmd/dlv/main.go

@@ -222,9 +222,41 @@ starts and attaches to it, and enable you to immediately begin debugging your pr
 	}
 	rootCommand.AddCommand(attachCommand)
 
+	// 'connect' subcommand.
+	connectCommand := &cobra.Command{
+		Use:   "connect [addr]",
+		Short: "Connect to a headless debug server.",
+		Long:  "Connect to a headless debug server.",
+		Run: func(cmd *cobra.Command, args []string) {
+			if len(args) == 0 {
+				fmt.Fprintf(os.Stderr, "An address was not provided. You must provide an address as the first argument.\n")
+				os.Exit(1)
+			}
+			addr := args[0]
+			if addr == "" {
+				fmt.Fprintf(os.Stderr, "An empty address was provided. You must provide an address as the first argument.\n")
+				os.Exit(1)
+			}
+			os.Exit(connect(addr))
+		},
+	}
+	rootCommand.AddCommand(connectCommand)
+
 	rootCommand.Execute()
 }
 
+func connect(addr string) int {
+	// Create and start a terminal - attach to running instance
+	var client service.Client
+	client = rpc.NewClient(addr)
+	term := terminal.New(client)
+	err, status := term.Run()
+	if err != nil {
+		fmt.Println(err)
+	}
+	return status
+}
+
 func execute(attachPid int, processArgs []string) int {
 	// Make a TCP listener
 	listener, err := net.Listen("tcp", Addr)