added command and pid display when the port is busy

internal/commands/tunnel_up.go

@@ -27,6 +27,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"syscall"
 	"text/template"
 )
 
@@ -379,8 +380,13 @@ func checkPort(port int) error {
 
 	l, err := net.ListenTCP("tcp", addr)
 	if err != nil {
-		logrus.Error(err)
-		return fmt.Errorf("port %d is not available. Please make sure there is no other process that is using the port %d", port, port)
+		command := fmt.Sprintf("lsof -i tcp:%d | grep LISTEN | awk '{print $1, \"(pid\", $2\")\"}'", port)
+		out, code := execCmd(exec.Command("bash", "-c", command))
+		if code == 0 {
+			logrus.Error(err)
+			return fmt.Errorf("port %d is in use by %s. Please stop the process or remove the port assigment so it will be auto-assigned", port, out)
+		}
+		return fmt.Errorf("error during run command: %s (exit code: %d)", command, code)
 	}
 
 	err = l.Close()
@@ -523,3 +529,21 @@ func setAWSCredentials(sess *session.Session) error {
 
 	return nil
 }
+
+// Execute command and return exited code.
+func execCmd(cmd *exec.Cmd) (string, int) {
+	var waitStatus syscall.WaitStatus
+	out, err := cmd.Output()
+	if err != nil {
+		if err != nil {
+			return err.Error(), 0
+		}
+		if exitError, ok := err.(*exec.ExitError); ok {
+			waitStatus = exitError.Sys().(syscall.WaitStatus)
+			return string(out), waitStatus.ExitStatus()
+		}
+	}
+
+	waitStatus = cmd.ProcessState.Sys().(syscall.WaitStatus)
+	return strings.TrimSpace(string(out)), waitStatus.ExitStatus()
+}