create pty, if input is not terminal

go.mod

@@ -27,6 +27,7 @@ require (
 	github.com/google/go-containerregistry/pkg/authn/k8schain v0.0.0-20210208222243-cbafe638a7a9
 	github.com/google/go-github v17.0.0+incompatible
 	github.com/google/go-querystring v1.0.0 // indirect
+	github.com/google/goterm v0.0.0-20200907032337-555d40f16ae2
 	github.com/google/martian v2.1.1-0.20190517191504-25dcb96d9e51+incompatible // indirect
 	github.com/google/slowjam v1.0.0
 	github.com/hashicorp/go-memdb v0.0.0-20180223233045-1289e7fffe71 // indirect

go.sum

@@ -360,6 +360,8 @@ github.com/google/gofuzz v1.0.0 h1:A8PeW59pxE9IoFRqBp37U+mSNaQoZ46F1f0f863XSXw=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/gofuzz v1.1.0 h1:Hsa8mG0dQ46ij8Sl2AYJDUv1oA9/d6Vk+3LG99Oe02g=
 github.com/google/gofuzz v1.1.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/goterm v0.0.0-20200907032337-555d40f16ae2 h1:CVuJwN34x4xM2aT4sIKhmeib40NeBPhRihNjQmpJsA4=
+github.com/google/goterm v0.0.0-20200907032337-555d40f16ae2/go.mod h1:nOFQdrUlIlx6M6ODdSpBj1NVA+VgLC6kmw60mkw34H4=
 github.com/google/martian v2.1.0+incompatible h1:/CP5g8u/VJHijgedC/Legn3BAbAaWPgecwXBIDzw5no=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
 github.com/google/martian v2.1.1-0.20190517191504-25dcb96d9e51+incompatible h1:xmapqc1AyLoB+ddYT6r04bD9lIjlOqGaREovi0SzFaE=

pkg/commands/run.go

@@ -18,6 +18,7 @@ package commands
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"os/user"
@@ -29,6 +30,7 @@ import (
 	"github.com/GoogleContainerTools/kaniko/pkg/dockerfile"
 	"github.com/GoogleContainerTools/kaniko/pkg/util"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/goterm/term"
 	"github.com/moby/buildkit/frontend/dockerfile/instructions"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -97,6 +99,19 @@ func RunDebugShell(config *v1.Config, buildArgs *dockerfile.BuildArgs, cmdRun *i
 
 	cmd.Env = env
 
+	// If input is not terminal, we will create pty
+	if fi, _ := os.Stdin.Stat(); (fi.Mode() & os.ModeCharDevice) == 0 {
+		logrus.Debugf("Creating PTY")
+		pty, err := term.OpenPTY()
+		if err != nil {
+			return err
+		}
+		defer pty.Close()
+		cmd.Stdin, cmd.Stdout, cmd.Stderr = pty.Slave, pty.Slave, pty.Slave
+		go io.Copy(pty.Master, os.Stdin)
+		go io.Copy(os.Stdout, pty.Master)
+	}
+
 	return cmd.Run()
 }