add interactive and tty to dockerfile, closes moby#1870

Docker-DCO-1.1-Signed-off-by: Scott Bessler <scottbessler@gmail.com> (github: creack)

docs/sources/reference/builder.rst

@@ -418,7 +418,23 @@ instruction.  For example:
 
 The output of the final ``pwd`` command in this Dockerfile would be ``/a/b/c``.
 
-3.11 ONBUILD
+3.12 INTERACTIVE
+----------------
+
+    ``INTERACTIVE true``
+
+The ``INTERACTIVE`` instruction keeps stdin open when running the
+image.
+
+3.13 TTY
+--------
+
+    ``TTY true``
+
+The ``TTY`` instruction allocates a pseudo-tty when running the
+image.
+
+3.14 ONBUILD
 ------------
 
     ``ONBUILD [INSTRUCTION]``

integration/buildfile_test.go

@@ -437,6 +437,34 @@ func TestBuildMaintainer(t *testing.T) {
 	}
 }
 
+func TestBuildInteractive(t *testing.T) {
+	img, err := buildImage(testContextTemplate{`
+        from {IMAGE}
+        interactive true
+    `, nil, nil}, t, nil, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !img.Config.OpenStdin {
+		t.Fail()
+	}
+}
+
+func TestBuildTty(t *testing.T) {
+	img, err := buildImage(testContextTemplate{`
+        from {IMAGE}
+        tty true
+    `, nil, nil}, t, nil, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !img.Config.Tty {
+		t.Fail()
+	}
+}
+
 func TestBuildUser(t *testing.T) {
 	img, err := buildImage(testContextTemplate{`
         from {IMAGE}

server/buildfile.go

@@ -21,6 +21,7 @@ import (
 	"reflect"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 )
 
@@ -304,6 +305,30 @@ func (b *buildFile) CmdEntrypoint(args string) error {
 	return nil
 }
 
+func (b *buildFile) CmdTty(args string) error {
+	if arg, err := strconv.ParseBool(args); err != nil {
+		return err
+	} else {
+		b.config.Tty = arg
+	}
+	if err := b.commit("", b.config.Cmd, fmt.Sprintf("TTY %s", args)); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (b *buildFile) CmdInteractive(args string) error {
+	if arg, err := strconv.ParseBool(args); err != nil {
+		return err
+	} else {
+		b.config.OpenStdin = arg
+	}
+	if err := b.commit("", b.config.Cmd, fmt.Sprintf("INTERACTIVE %s", args)); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (b *buildFile) CmdExpose(args string) error {
 	portsTab := strings.Split(args, " ")