packer: Add MachineReadableUi

packer/ui.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+	"time"
 	"unicode"
 )
 
@@ -63,6 +64,12 @@ type BasicUi struct {
 	interrupted bool
 }
 
+// MachineReadableUi is a UI that only outputs machine-readable output
+// to the given Writer.
+type MachineReadableUi struct {
+	Writer io.Writer
+}
+
 func (u *ColoredUi) Ask(query string) (string, error) {
 	return u.Ui.Ask(u.colorize(query, u.Color, true))
 }
@@ -232,3 +239,42 @@ func (rw *BasicUi) Error(message string) {
 func (rw *BasicUi) Machine(t string, args ...string) {
 	log.Printf("machine readable: %s %#v", t, args)
 }
+
+func (u *MachineReadableUi) Ask(query string) (string, error) {
+	return "", errors.New("machine-readable UI can't ask")
+}
+
+func (u *MachineReadableUi) Say(message string) {
+	u.Machine("ui", "say", message)
+}
+
+func (u *MachineReadableUi) Message(message string) {
+	u.Machine("ui", "message", message)
+}
+
+func (u *MachineReadableUi) Error(message string) {
+	u.Machine("ui", "error", message)
+}
+
+func (u *MachineReadableUi) Machine(category string, args ...string) {
+	now := time.Now().UTC()
+
+	// Determine if we have a target, and set it
+	target := ""
+	commaIdx := strings.Index(category, ",")
+	if commaIdx > -1 {
+		target = category[0:commaIdx]
+		category = category[commaIdx+1:]
+	}
+
+	// Prepare the args
+	for i, v := range args {
+		args[i] = strings.Replace(v, ",", "%!(PACKER_COMMA)", -1)
+	}
+	argsString := strings.Join(args, ",")
+
+	_, err := fmt.Fprintf(u.Writer, "%d,%s,%s,%s", now.Unix(), target, category, argsString)
+	if err != nil {
+		panic(err)
+	}
+}

packer/ui_test.go

@@ -3,6 +3,7 @@ package packer
 import (
 	"bytes"
 	"cgl.tideland.biz/asserts"
+	"strings"
 	"testing"
 )
 
@@ -106,6 +107,44 @@ func TestBasicUi_Say(t *testing.T) {
 	assert.Equal(readWriter(bufferUi), "5\n", "formatting")
 }
 
+func TestMachineReadableUi_ImplUi(t *testing.T) {
+	var raw interface{}
+	raw = &MachineReadableUi{}
+	if _, ok := raw.(Ui); !ok {
+		t.Fatalf("MachineReadableUi must implement Ui")
+	}
+}
+
+func TestMachineReadableUi(t *testing.T) {
+	var data, expected string
+
+	buf := new(bytes.Buffer)
+	ui := &MachineReadableUi{Writer: buf}
+
+	ui.Machine("foo", "bar", "baz")
+	data = strings.SplitN(buf.String(), ",", 2)[1]
+	expected = ",foo,bar,baz"
+	if data != expected {
+		t.Fatalf("bad: %s", data)
+	}
+
+	buf.Reset()
+	ui.Machine("mitchellh,foo", "bar", "baz")
+	data = strings.SplitN(buf.String(), ",", 2)[1]
+	expected = "mitchellh,foo,bar,baz"
+	if data != expected {
+		t.Fatalf("bad: %s", data)
+	}
+
+	buf.Reset()
+	ui.Machine("foo", "foo,bar")
+	data = strings.SplitN(buf.String(), ",", 2)[1]
+	expected = ",foo,foo%!(PACKER_COMMA)bar"
+	if data != expected {
+		t.Fatalf("bad: %s", data)
+	}
+}
+
 // This reads the output from the bytes.Buffer in our test object
 // and then resets the buffer.
 func readWriter(ui *BasicUi) (result string) {