Add TTY detection for non-interactive environments

errs/errs.go

@@ -328,3 +328,29 @@ func FileError(err error, filename string) error {
 type FriendlyError interface {
 	Message() string
 }
+
+// RequiredInputError is returned when a prompt is required but no terminal is
+// available. It provides a helpful error message indicating which flag can be
+// used to provide the value non-interactively.
+type RequiredInputError struct {
+	// FieldName is the name of the field that requires input (e.g., "password", "provisioner")
+	FieldName string
+	// Flag is the optional flag name that can be used to provide the value non-interactively
+	Flag string
+}
+
+// Error implements the error interface.
+func (e *RequiredInputError) Error() string {
+	if e.Flag != "" {
+		return fmt.Sprintf("cannot prompt for %s: no terminal available. Use '--%s' flag to provide this value non-interactively", e.FieldName, e.Flag)
+	}
+	return fmt.Sprintf("cannot prompt for %s: no terminal available", e.FieldName)
+}
+
+// NewRequiredInputError creates a new RequiredInputError with the given field name and flag.
+func NewRequiredInputError(fieldName, flag string) *RequiredInputError {
+	return &RequiredInputError{
+		FieldName: fieldName,
+		Flag:      flag,
+	}
+}

go.mod

@@ -14,6 +14,7 @@ require (
 	go.step.sm/crypto v0.75.0
 	golang.org/x/net v0.49.0
 	golang.org/x/sys v0.40.0
+	golang.org/x/term v0.39.0
 )
 
 require (

ui/ui.go

@@ -11,8 +11,27 @@ import (
 	"github.com/manifoldco/promptui"
 	"github.com/pkg/errors"
 	"go.step.sm/crypto/randutil"
+	"golang.org/x/term"
 )
 
+// CanPrompt returns true if the current environment supports interactive
+// prompts. It checks if stdin is a terminal, or if /dev/tty is available.
+// This function should be called before attempting to prompt for user input
+// to provide better error messages in non-interactive environments like
+// systemd services, GitHub Actions, or Docker containers.
+func CanPrompt() bool {
+	// First check if stdin is a terminal
+	if term.IsTerminal(int(os.Stdin.Fd())) {
+		return true
+	}
+	// Fall back to checking if /dev/tty is available
+	if tty, err := os.Open("/dev/tty"); err == nil {
+		tty.Close()
+		return true
+	}
+	return false
+}
+
 // stderr implements an io.WriteCloser that skips the terminal bell character
 // (ASCII code 7), and writes the rest to os.Stderr. It's used to replace
 // readline.Stdout, that is the package used by promptui to display the prompts.
@@ -299,7 +318,7 @@ func preparePromptTerminal() (func(), error) {
 	if !readline.DefaultIsTerminal() {
 		tty, err := os.Open("/dev/tty")
 		if err != nil {
-			return nothing, errors.Wrap(err, "error allocating terminal")
+			return nothing, errors.New("cannot perform interactive prompts: no terminal available (running in non-interactive environment like systemd, CI, or Docker?)")
 		}
 		clean := func() {
 			tty.Close()
@@ -329,7 +348,7 @@ func prepareSelectTerminal() (func(), error) {
 	if !readline.DefaultIsTerminal() {
 		tty, err := os.Open("/dev/tty")
 		if err != nil {
-			return nothing, errors.Wrap(err, "error allocating terminal")
+			return nothing, errors.New("cannot perform interactive selection: no terminal available (running in non-interactive environment like systemd, CI, or Docker?)")
 		}
 		clean := func() {
 			tty.Close()