packer/plugin: connect stdin to parent stdin

packer/plugin/client.go

@@ -216,6 +216,7 @@ func (c *Client) Start() (address string, err error) {
 	cmd := c.config.Cmd
 	cmd.Env = append(cmd.Env, os.Environ()...)
 	cmd.Env = append(cmd.Env, env...)
+	cmd.Stdin = os.Stdin
 	cmd.Stderr = stderr
 	cmd.Stdout = stdout
 

packer/plugin/client_test.go

 package plugin
 
 import (
+	"io/ioutil"
+	"os"
 	"testing"
 	"time"
 )
@@ -47,3 +49,50 @@ func TestClient_Start_Timeout(t *testing.T) {
 		t.Fatal("err should not be nil")
 	}
 }
+
+func TestClient_Stdin(t *testing.T) {
+	// Overwrite stdin for this test with a temporary file
+	tf, err := ioutil.TempFile("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Remove(tf.Name())
+	defer tf.Close()
+
+	if _, err = tf.WriteString("hello"); err != nil {
+		t.Fatalf("error: %s", err)
+	}
+
+	if err = tf.Sync(); err != nil {
+		t.Fatalf("error: %s", err)
+	}
+
+	if _, err = tf.Seek(0, 0); err != nil {
+		t.Fatalf("error: %s", err)
+	}
+
+	oldStdin := os.Stdin
+	defer func() { os.Stdin = oldStdin }()
+	os.Stdin = tf
+
+	process := helperProcess("stdin")
+	c := NewClient(&ClientConfig{Cmd: process})
+	defer c.Kill()
+
+	_, err = c.Start()
+	if err != nil {
+		t.Fatalf("error: %s", err)
+	}
+
+	for {
+		if c.Exited() {
+			break
+		}
+
+		time.Sleep(50 * time.Millisecond)
+	}
+
+	if !process.ProcessState.Success() {
+		t.Fatal("process didn't exit cleanly")
+	}
+}

packer/plugin/plugin_test.go

@@ -2,6 +2,7 @@ package plugin
 
 import (
 	"fmt"
+	"log"
 	"os"
 	"os/exec"
 	"testing"
@@ -65,6 +66,19 @@ func TestHelperProcess(*testing.T) {
 		ServeProvisioner(new(helperProvisioner))
 	case "start-timeout":
 		time.Sleep(1 * time.Minute)
+		os.Exit(1)
+	case "stdin":
+		fmt.Println(":1234")
+		data := make([]byte, 5)
+		if _, err := os.Stdin.Read(data); err != nil {
+			log.Printf("stdin read error: %s", err)
+			os.Exit(100)
+		}
+
+		if string(data) == "hello" {
+			os.Exit(0)
+		}
+
 		os.Exit(1)
 	default:
 		fmt.Fprintf(os.Stderr, "Unknown command: %q\n", cmd)