Use custom prompter for bundle template inputs (#663)

## Changes
Prompt UI glitches often. We are switching to a custom implementation of
a simple prompter which is much more stable.
This also allows new lines in prompts which has been an ask by the
mlflow team.

## Tests
Tested manually

bundle/deploy/files/delete.go

@@ -27,7 +27,7 @@ func (m *delete) Apply(ctx context.Context, b *bundle.Bundle) error {
 
 	red := color.New(color.FgRed).SprintFunc()
 	if !b.AutoApprove {
-		proceed, err := cmdio.Ask(ctx, fmt.Sprintf("\n%s and all files in it will be %s Proceed?", b.Config.Workspace.RootPath, red("deleted permanently!")))
+		proceed, err := cmdio.AskYesOrNo(ctx, fmt.Sprintf("\n%s and all files in it will be %s Proceed?", b.Config.Workspace.RootPath, red("deleted permanently!")))
 		if err != nil {
 			return err
 		}

bundle/deploy/terraform/destroy.go

@@ -89,7 +89,7 @@ func (w *destroy) Apply(ctx context.Context, b *bundle.Bundle) error {
 	// Ask for confirmation, if needed
 	if !b.Plan.ConfirmApply {
 		red := color.New(color.FgRed).SprintFunc()
-		b.Plan.ConfirmApply, err = cmdio.Ask(ctx, fmt.Sprintf("\nThis will permanently %s resources! Proceed?", red("destroy")))
+		b.Plan.ConfirmApply, err = cmdio.AskYesOrNo(ctx, fmt.Sprintf("\nThis will permanently %s resources! Proceed?", red("destroy")))
 		if err != nil {
 			return err
 		}

libs/cmdio/logger.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strings"
 
 	"github.com/databricks/cli/libs/flags"
 )
@@ -74,33 +75,64 @@ func LogError(ctx context.Context, err error) {
 	})
 }
 
-func Ask(ctx context.Context, question string) (bool, error) {
+func Ask(ctx context.Context, question, defaultVal string) (string, error) {
 	logger, ok := FromContext(ctx)
 	if !ok {
 		logger = Default()
 	}
-	return logger.Ask(question)
+	return logger.Ask(question, defaultVal)
 }
 
-func (l *Logger) Ask(question string) (bool, error) {
+func AskYesOrNo(ctx context.Context, question string) (bool, error) {
-	if l.Mode == flags.ModeJson {
+	logger, ok := FromContext(ctx)
-		return false, fmt.Errorf("question prompts are not supported in json mode")
+	if !ok {
+		logger = Default()
 	}
 
 	// Add acceptable answers to the question prompt.
-	question += ` [y/n]:`
+	question += ` [y/n]`
-	l.Writer.Write([]byte(question))
-	ans, err := l.Reader.ReadString('\n')
 
+	// Ask the question
+	ans, err := logger.Ask(question, "")
 	if err != nil {
 		return false, err
 	}
 
-	if ans == "y\n" {
+	if ans == "y" {
 		return true, nil
-	} else {
-		return false, nil
 	}
+	return false, nil
+}
+
+func (l *Logger) Ask(question string, defaultVal string) (string, error) {
+	if l.Mode == flags.ModeJson {
+		return "", fmt.Errorf("question prompts are not supported in json mode")
+	}
+
+	// Add default value to question prompt.
+	if defaultVal != "" {
+		question += fmt.Sprintf(` [%s]`, defaultVal)
+	}
+	question += `: `
+
+	// print prompt
+	_, err := l.Writer.Write([]byte(question))
+	if err != nil {
+		return "", err
+	}
+
+	// read user input. Trim new line characters
+	ans, err := l.Reader.ReadString('\n')
+	if err != nil {
+		return "", err
+	}
+	ans = strings.Trim(ans, "\n\r")
+
+	// Return default value if user just presses enter
+	if ans == "" {
+		return defaultVal, nil
+	}
+	return ans, nil
 }
 
 func (l *Logger) writeJson(event Event) {

libs/cmdio/logger_test.go

@@ -9,6 +9,6 @@ import (
 
 func TestAskFailedInJsonMode(t *testing.T) {
 	l := NewLogger(flags.ModeJson)
-	_, err := l.Ask("What is your spirit animal?")
+	_, err := l.Ask("What is your spirit animal?", "")
 	assert.ErrorContains(t, err, "question prompts are not supported in json mode")
 }

libs/template/config.go

@@ -123,22 +123,18 @@ func (c *config) promptForValues() error {
 			continue
 		}
 
-		// Initialize Prompt dialog
-		var err error
-		prompt := cmdio.Prompt(c.ctx)
-		prompt.Label = property.Description
-		prompt.AllowEdit = true
-
 		// Compute default value to display by converting it to a string
+		var defaultVal string
+		var err error
 		if property.Default != nil {
-			prompt.Default, err = toString(property.Default, property.Type)
+			defaultVal, err = toString(property.Default, property.Type)
 			if err != nil {
 				return err
 			}
 		}
 
 		// Get user input by running the prompt
-		userInput, err := prompt.Run()
+		userInput, err := cmdio.Ask(c.ctx, property.Description, defaultVal)
 		if err != nil {
 			return err
 		}