Merge pull request #739 from mitchellh/f-prov-pause-before

Provisioner "pause_before" meta-parameter

packer/provisioner.go

 package packer
 
 import (
+	"fmt"
 	"sync"
+	"time"
 )
 
 // A provisioner is responsible for installing and configuring software
@@ -65,3 +67,80 @@ 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
+	ui.Say(fmt.Sprintf("Pausing %s before the next provisioner...", p.PauseBefore))
+	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.go

@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"os"
 	"sort"
+	"time"
 )
 
 // The rawTemplate struct represents the structure of a template read
@@ -63,10 +64,13 @@ type RawPostProcessorConfig struct {
 type RawProvisionerConfig struct {
 	TemplateOnlyExcept `mapstructure:",squash"`
 
-	Type     string
-	Override map[string]interface{}
+	Type           string
+	Override       map[string]interface{}
+	RawPauseBefore string `mapstructure:"pause_before"`
 
 	RawConfig interface{}
+
+	pauseBefore time.Duration
 }
 
 // RawVariable represents a variable configuration within a template.
@@ -289,6 +293,19 @@ func ParseTemplate(data []byte) (t *Template, err error) {
 			}
 		}
 
+		// Setup the pause settings
+		if raw.RawPauseBefore != "" {
+			duration, err := time.ParseDuration(raw.RawPauseBefore)
+			if err != nil {
+				errors = append(
+					errors, fmt.Errorf(
+						"provisioner %d: pause_before invalid: %s",
+						i+1, err))
+			}
+
+			raw.pauseBefore = duration
+		}
+
 		raw.RawConfig = v
 	}
 
@@ -498,6 +515,13 @@ func (t *Template) Build(name string, components *ComponentFinder) (b Build, err
 			}
 		}
 
+		if rawProvisioner.pauseBefore > 0 {
+			provisioner = &PausedProvisioner{
+				PauseBefore: rawProvisioner.pauseBefore,
+				Provisioner: provisioner,
+			}
+		}
+
 		coreProv := coreBuildProvisioner{provisioner, configs}
 		provisioners = append(provisioners, coreProv)
 	}

packer/template_test.go

@@ -6,6 +6,7 @@ import (
 	"reflect"
 	"sort"
 	"testing"
+	"time"
 )
 
 func testTemplateComponentFinder() *ComponentFinder {
@@ -445,6 +446,38 @@ func TestParseTemplate_Provisioners(t *testing.T) {
 	}
 }
 
+func TestParseTemplate_ProvisionerPauseBefore(t *testing.T) {
+	data := `
+	{
+		"builders": [{"type": "foo"}],
+
+		"provisioners": [
+			{
+				"type": "shell",
+				"pause_before": "10s"
+			}
+		]
+	}
+	`
+
+	result, err := ParseTemplate([]byte(data))
+	if err != nil {
+		t.Fatal("err: %s", err)
+	}
+	if result == nil {
+		t.Fatal("should have result")
+	}
+	if len(result.Provisioners) != 1 {
+		t.Fatalf("bad: %#v", result.Provisioners)
+	}
+	if result.Provisioners[0].Type != "shell" {
+		t.Fatalf("bad: %#v", result.Provisioners[0].Type)
+	}
+	if result.Provisioners[0].pauseBefore != 10*time.Second {
+		t.Fatalf("bad: %s", result.Provisioners[0].pauseBefore)
+	}
+}
+
 func TestParseTemplate_Variables(t *testing.T) {
 	data := `
 	{
@@ -1278,6 +1311,70 @@ func TestTemplate_Build_ProvisionerOverrideBad(t *testing.T) {
 	}
 }
 
+func TestTemplateBuild_ProvisionerPauseBefore(t *testing.T) {
+	data := `
+	{
+		"builders": [
+			{
+				"name": "test1",
+				"type": "test-builder"
+			}
+		],
+
+		"provisioners": [
+			{
+				"type": "test-prov",
+				"pause_before": "5s"
+			}
+		]
+	}
+	`
+
+	template, err := ParseTemplate([]byte(data))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	builder := new(MockBuilder)
+	builderMap := map[string]Builder{
+		"test-builder": builder,
+	}
+
+	provisioner := &MockProvisioner{}
+	provisionerMap := map[string]Provisioner{
+		"test-prov": provisioner,
+	}
+
+	builderFactory := func(n string) (Builder, error) { return builderMap[n], nil }
+	provFactory := func(n string) (Provisioner, error) { return provisionerMap[n], nil }
+	components := &ComponentFinder{
+		Builder:     builderFactory,
+		Provisioner: provFactory,
+	}
+
+	// Get the build, verifying we can get it without issue, but also
+	// that the proper builder was looked up and used for the build.
+	build, err := template.Build("test1", components)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	coreBuild, ok := build.(*coreBuild)
+	if !ok {
+		t.Fatal("should be okay")
+	}
+	if len(coreBuild.provisioners) != 1 {
+		t.Fatalf("bad: %#v", coreBuild.provisioners)
+	}
+	if pp, ok := coreBuild.provisioners[0].provisioner.(*PausedProvisioner); !ok {
+		t.Fatalf("should be paused provisioner")
+	} else {
+		if pp.PauseBefore != 5*time.Second {
+			t.Fatalf("bad: %#v", pp.PauseBefore)
+		}
+	}
+}
+
 func TestTemplateBuild_variables(t *testing.T) {
 	data := `
 	{

website/source/docs/templates/provisioners.html.markdown

@@ -112,3 +112,26 @@ JSON object where the key is the name of a [builder definition](/docs/templates/
 The value of this is in turn another JSON object. This JSON object simply
 contains the provisioner configuration as normal. This configuration is merged
 into the default provisioner configuration.
+
+## Pausing Before Running
+
+With certain provisioners it is sometimes desirable to pause for some period
+of time before running it. Specifically, in cases where a provisioner reboots
+the machine, you may want to wait for some period of time before starting
+the next provisioner.
+
+Every provisioner definition in a Packer template can take a special
+configuration `pause_before` that is the amount of time to pause before
+running that provisioner. By default, there is no pause. An example
+is shown below:
+
+<pre class="prettyprint">
+{
+  "type": "shell",
+  "script": "script.sh",
+  "pause_before": "10s"
+}
+</pre>
+
+For the above provisioner, Packer will wait 10 seconds before uploading
+and executing the shell script.