packer: Introduce Cancel() method to Builder

builder/amazonebs/builder.go

@@ -102,3 +102,6 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook) packer.Artifact {
 	// Build the artifact and return it
 	return &artifact{state["amis"].(map[string]string)}
 }
+
+func (b *Builder) Cancel() {
+}

packer/builder.go

@@ -2,14 +2,17 @@ package packer
 
 // Implementers of Builder are responsible for actually building images
 // on some platform given some configuration.
-//
+type Builder interface {
 	// Prepare is responsible for reading in some configuration, in the raw form
 	// of map[string]interface{}, and storing that state for use later. Any setup
 	// should be done in this method. Note that NO side effects should really take
 	// place in prepare. It is meant as a state setup step only.
-//
-// Run is where the actual build should take place. It takes a Build and a Ui.
-type Builder interface {
 	Prepare(config interface{}) error
+
+	// Run is where the actual build should take place. It takes a Build and a Ui.
 	Run(ui Ui, hook Hook) Artifact
+
+	// Cancel cancels a possibly running Builder. This should block until
+	// the builder actually cancels and cleans up after itself.
+	Cancel()
 }

packer/builder_test.go

@@ -6,6 +6,7 @@ type TestBuilder struct {
 	runCalled     bool
 	runHook       Hook
 	runUi         Ui
+	cancelCalled  bool
 }
 
 func (tb *TestBuilder) Prepare(config interface{}) error {
@@ -20,3 +21,7 @@ func (tb *TestBuilder) Run(ui Ui, h Hook) Artifact {
 	tb.runUi = ui
 	return nil
 }
+
+func (tb *TestBuilder) Cancel() {
+	tb.cancelCalled = true
+}

packer/plugin/builder.go

@@ -31,6 +31,9 @@ func (b *cmdBuilder) Run(ui packer.Ui, hook packer.Hook) packer.Artifact {
 	return b.builder.Run(ui, hook)
 }
 
+func (b *cmdBuilder) Cancel() {
+}
+
 func (c *cmdBuilder) checkExit(p interface{}, cb func()) {
 	if c.client.Exited() && cb != nil {
 		cb()

packer/plugin/builder_test.go

@@ -17,6 +17,8 @@ func (helperBuilder) Run(packer.Ui, packer.Hook) packer.Artifact {
 	return nil
 }
 
+func (helperBuilder) Cancel() {}
+
 func TestBuilder_NoExist(t *testing.T) {
 	assert := asserts.NewTestingAsserts(t, true)
 

packer/rpc/builder.go

@@ -60,6 +60,10 @@ func (b *builder) Run(ui packer.Ui, hook packer.Hook) packer.Artifact {
 	return Artifact(client)
 }
 
+func (b *builder) Cancel() {
+
+}
+
 func (b *BuilderServer) Prepare(args *BuilderPrepareArgs, reply *error) error {
 	err := b.builder.Prepare(args.Config)
 	if err != nil {

packer/rpc/builder_test.go

@@ -15,6 +15,7 @@ type testBuilder struct {
 	runCalled     bool
 	runHook       packer.Hook
 	runUi         packer.Ui
+	cancelCalled  bool
 }
 
 func (b *testBuilder) Prepare(config interface{}) error {
@@ -30,6 +31,10 @@ func (b *testBuilder) Run(ui packer.Ui, hook packer.Hook) packer.Artifact {
 	return testBuilderArtifact
 }
 
+func (b *testBuilder) Cancel() {
+	b.cancelCalled = true
+}
+
 func TestBuilderRPC(t *testing.T) {
 	assert := asserts.NewTestingAsserts(t, true)
 

packer/ui_test.go

@@ -20,7 +20,7 @@ func TestColoredUi(t *testing.T) {
 	ui := &ColoredUi{UiColorRed, bufferUi}
 
 	ui.Say("foo")
-	assert.Equal(readWriter(bufferUi), "\033[0;31;40mfoo\033[0m\n", "should have color")
+	assert.Equal(readWriter(bufferUi), "\033[1;31;40mfoo\033[0m\n", "should have color")
 }
 
 func TestPrefixedUi(t *testing.T) {