packer: PausedProvisioner

packer/provisioner.go

@@ -2,6 +2,7 @@ package packer
 
 import (
 	"sync"
+	"time"
 )
 
 // A provisioner is responsible for installing and configuring software
@@ -65,3 +66,79 @@ func (h *ProvisionHook) Cancel() {
 		h.runningProvisioner.Cancel()
 	}
 }
+
+// PausedProvisioner is a Provisioner implementation that pauses before
+// the provisioner is actually run.
+type PausedProvisioner struct {
+	PauseBefore time.Duration
+	Provisioner Provisioner
+
+	cancelCh chan struct{}
+	doneCh   chan struct{}
+	lock     sync.Mutex
+}
+
+func (p *PausedProvisioner) Prepare(raws ...interface{}) error {
+	return p.Provisioner.Prepare(raws...)
+}
+
+func (p *PausedProvisioner) Provision(ui Ui, comm Communicator) error {
+	p.lock.Lock()
+	cancelCh := make(chan struct{})
+	p.cancelCh = cancelCh
+
+	// Setup the done channel, which is trigger when we're done
+	doneCh := make(chan struct{})
+	defer close(doneCh)
+	p.doneCh = doneCh
+	p.lock.Unlock()
+
+	defer func() {
+		p.lock.Lock()
+		defer p.lock.Unlock()
+		if p.cancelCh == cancelCh {
+			p.cancelCh = nil
+		}
+		if p.doneCh == doneCh {
+			p.doneCh = nil
+		}
+	}()
+
+	// Use a select to determine if we get cancelled during the wait
+	select {
+	case <-time.After(p.PauseBefore):
+	case <-cancelCh:
+		return nil
+	}
+
+	provDoneCh := make(chan error, 1)
+	go p.provision(provDoneCh, ui, comm)
+
+	select {
+	case err := <-provDoneCh:
+		return err
+	case <-cancelCh:
+		p.Provisioner.Cancel()
+		return <-provDoneCh
+	}
+}
+
+func (p *PausedProvisioner) Cancel() {
+	var doneCh chan struct{}
+
+	p.lock.Lock()
+	if p.cancelCh != nil {
+		close(p.cancelCh)
+		p.cancelCh = nil
+	}
+	if p.doneCh != nil {
+		doneCh = p.doneCh
+	}
+	p.lock.Unlock()
+
+	<-doneCh
+}
+
+func (p *PausedProvisioner) provision(result chan<- error, ui Ui, comm Communicator) {
+	result <- p.Provisioner.Provision(ui, comm)
+}

packer/provisioner_mock.go

@@ -5,11 +5,12 @@ package packer
 type MockProvisioner struct {
 	ProvFunc func() error
 
-	PrepCalled   bool
-	PrepConfigs  []interface{}
-	ProvCalled   bool
-	ProvUi       Ui
-	CancelCalled bool
+	PrepCalled       bool
+	PrepConfigs      []interface{}
+	ProvCalled       bool
+	ProvCommunicator Communicator
+	ProvUi           Ui
+	CancelCalled     bool
 }
 
 func (t *MockProvisioner) Prepare(configs ...interface{}) error {
@@ -20,6 +21,7 @@ func (t *MockProvisioner) Prepare(configs ...interface{}) error {
 
 func (t *MockProvisioner) Provision(ui Ui, comm Communicator) error {
 	t.ProvCalled = true
+	t.ProvCommunicator = comm
 	t.ProvUi = ui
 
 	if t.ProvFunc == nil {

packer/provisioner_test.go

@@ -80,3 +80,94 @@ func TestProvisionHook_cancel(t *testing.T) {
 }
 
 // TODO(mitchellh): Test that they're run in the proper order
+
+func TestPausedProvisioner_impl(t *testing.T) {
+	var _ Provisioner = new(PausedProvisioner)
+}
+
+func TestPausedProvisionerPrepare(t *testing.T) {
+	mock := new(MockProvisioner)
+	prov := &PausedProvisioner{
+		Provisioner: mock,
+	}
+
+	prov.Prepare(42)
+	if !mock.PrepCalled {
+		t.Fatal("prepare should be called")
+	}
+	if mock.PrepConfigs[0] != 42 {
+		t.Fatal("should have proper configs")
+	}
+}
+
+func TestPausedProvisionerProvision(t *testing.T) {
+	mock := new(MockProvisioner)
+	prov := &PausedProvisioner{
+		Provisioner: mock,
+	}
+
+	ui := testUi()
+	comm := new(MockCommunicator)
+	prov.Provision(ui, comm)
+	if !mock.ProvCalled {
+		t.Fatal("prov should be called")
+	}
+	if mock.ProvUi != ui {
+		t.Fatal("should have proper ui")
+	}
+	if mock.ProvCommunicator != comm {
+		t.Fatal("should have proper comm")
+	}
+}
+
+func TestPausedProvisionerProvision_waits(t *testing.T) {
+	mock := new(MockProvisioner)
+	prov := &PausedProvisioner{
+		PauseBefore: 50 * time.Millisecond,
+		Provisioner: mock,
+	}
+
+	dataCh := make(chan struct{})
+	mock.ProvFunc = func() error {
+		close(dataCh)
+		return nil
+	}
+
+	go prov.Provision(testUi(), new(MockCommunicator))
+
+	select {
+	case <-time.After(10 * time.Millisecond):
+	case <-dataCh:
+		t.Fatal("should not be called")
+	}
+
+	select {
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("never called")
+	case <-dataCh:
+	}
+}
+
+func TestPausedProvisionerCancel(t *testing.T) {
+	mock := new(MockProvisioner)
+	prov := &PausedProvisioner{
+		Provisioner: mock,
+	}
+
+	provCh := make(chan struct{})
+	mock.ProvFunc = func() error {
+		close(provCh)
+		time.Sleep(10 * time.Millisecond)
+		return nil
+	}
+
+	// Start provisioning and wait for it to start
+	go prov.Provision(testUi(), new(MockCommunicator))
+	<-provCh
+
+	// Cancel it
+	prov.Cancel()
+	if !mock.CancelCalled {
+		t.Fatal("cancel should be called")
+	}
+}

packer/template_test.go

@@ -473,7 +473,7 @@ func TestParseTemplate_ProvisionerPauseBefore(t *testing.T) {
 	if result.Provisioners[0].Type != "shell" {
 		t.Fatalf("bad: %#v", result.Provisioners[0].Type)
 	}
-	if result.Provisioners[0].pauseBefore != 10 * time.Second {
+	if result.Provisioners[0].pauseBefore != 10*time.Second {
 		t.Fatalf("bad: %s", result.Provisioners[0].pauseBefore)
 	}
 }