Add --non-interactive flag and improve TTY detection

Add support for non-interactive environments by:
- Adding --non-interactive global flag (also STEP_NON_INTERACTIVE env var)
- Checking for terminal availability before prompting for passwords
- Returning helpful error messages when prompts fail in CI/systemd/Docker

This change requires smallstep/cli-utils#210 which adds:
- ui.CanPrompt() for TTY detection
- errs.RequiredInputError for descriptive error messages

Fixes #674

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: tashian

go.mod

@@ -128,7 +128,7 @@ require (
 	go.opentelemetry.io/otel/metric v1.38.0 // indirect
 	go.opentelemetry.io/otel/trace v1.38.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
-	golang.org/x/net v0.48.0 // indirect
+	golang.org/x/net v0.49.0 // indirect
 	golang.org/x/oauth2 v0.33.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/text v0.33.0 // indirect

go.sum

@@ -402,8 +402,8 @@ golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/net v0.15.0/go.mod h1:idbUs1IY1+zTqbi8yxTbhexhEEk5ur9LInksu6HrEpk=
 golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=
-golang.org/x/net v0.48.0 h1:zyQRTTrjc33Lhh0fBgT/H3oZq9WuvRR5gPC70xpDiQU=
-golang.org/x/net v0.48.0/go.mod h1:+ndRgGjkh8FGtu1w1FGbEC31if4VrNVMuKTgcAAnQRY=
+golang.org/x/net v0.49.0 h1:eeHFmOGUTtaaPSGNmjBKpbng9MulQsJURQUAfUwY++o=
+golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
 golang.org/x/oauth2 v0.33.0 h1:4Q+qn+E5z8gPRJfmRy7C2gGG3T4jIprK6aSYgTXGRpo=
 golang.org/x/oauth2 v0.33.0/go.mod h1:lzm5WQJQwKZ3nwavOZ3IS5Aulzxi68dUSgRHujetwEA=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

internal/cmd/root.go

@@ -13,6 +13,7 @@ import (
 	"github.com/urfave/cli"
 
 	"github.com/smallstep/cli-utils/command"
+	"github.com/smallstep/cli-utils/errs"
 	"github.com/smallstep/cli-utils/fileutil"
 	"github.com/smallstep/cli-utils/step"
 	"github.com/smallstep/cli-utils/ui"
@@ -96,9 +97,15 @@ func newApp(stdout, stderr io.Writer) *cli.App {
 	// Define default file writers and prompters for go.step.sm/crypto
 	pemutil.WriteFile = fileutil.WriteFile
 	pemutil.PromptPassword = func(msg string) ([]byte, error) {
+		if !ui.CanPrompt() {
+			return nil, errs.NewRequiredInputError("password", "password-file")
+		}
 		return ui.PromptPassword(msg)
 	}
 	jose.PromptPassword = func(msg string) ([]byte, error) {
+		if !ui.CanPrompt() {
+			return nil, errs.NewRequiredInputError("password", "password-file")
+		}
 		return ui.PromptPassword(msg)
 	}
 
@@ -130,6 +137,13 @@ func newApp(stdout, stderr io.Writer) *cli.App {
 		Usage: "path to the config file to use for CLI flags",
 	})
 
+	// Flag to disable interactive prompts
+	app.Flags = append(app.Flags, cli.BoolFlag{
+		Name:   "non-interactive",
+		Usage:  "disable interactive prompts; commands will fail if required input is missing",
+		EnvVar: "STEP_NON_INTERACTIVE",
+	})
+
 	// Action runs on `step` or `step <command>` if the command is not enabled.
 	app.Action = func(ctx *cli.Context) error {
 		args := ctx.Args()