packer: builder prepare can return warnings

packer/build.go

@@ -38,8 +38,9 @@ type Build interface {
 	Name() string
 
 	// Prepare configures the various components of this build and reports
-	// any errors in doing so (such as syntax errors, validation errors, etc.)
-	Prepare(v map[string]string) error
+	// any errors in doing so (such as syntax errors, validation errors, etc.).
+	// It also reports any warnings.
+	Prepare(v map[string]string) ([]string, error)
 
 	// Run runs the actual builder, returning an artifact implementation
 	// of what is built. If anything goes wrong, an error is returned.
@@ -115,7 +116,7 @@ func (b *coreBuild) Name() string {
 // Prepare prepares the build by doing some initialization for the builder
 // and any hooks. This _must_ be called prior to Run. The parameter is the
 // overrides for the variables within the template (if any).
-func (b *coreBuild) Prepare(userVars map[string]string) (err error) {
+func (b *coreBuild) Prepare(userVars map[string]string) (warn []string, err error) {
 	b.l.Lock()
 	defer b.l.Unlock()
 
@@ -154,7 +155,7 @@ func (b *coreBuild) Prepare(userVars map[string]string) (err error) {
 	// If there were any problem with variables, return an error right
 	// away because we can't be certain anything else will actually work.
 	if len(varErrs) > 0 {
-		return &MultiError{
+		return nil, &MultiError{
 			Errors: varErrs,
 		}
 	}
@@ -168,7 +169,7 @@ func (b *coreBuild) Prepare(userVars map[string]string) (err error) {
 	}
 
 	// Prepare the builder
-	err = b.builder.Prepare(b.builderConfig, packerConfig)
+	warn, err = b.builder.Prepare(b.builderConfig, packerConfig)
 	if err != nil {
 		log.Printf("Build '%s' prepare failure: %s\n", b.name, err)
 		return

packer/build_test.go

@@ -8,7 +8,7 @@ import (
 func testBuild() *coreBuild {
 	return &coreBuild{
 		name:          "test",
-		builder:       &TestBuilder{artifactId: "b"},
+		builder:       &MockBuilder{ArtifactId: "b"},
 		builderConfig: 42,
 		builderType:   "foo",
 		hooks: map[string][]Hook{
@@ -26,10 +26,6 @@ func testBuild() *coreBuild {
 	}
 }
 
-func testBuilder() *TestBuilder {
-	return &TestBuilder{}
-}
-
 func testDefaultPackerConfig() map[string]interface{} {
 	return map[string]interface{}{
 		BuildNameConfigKey:     "test",
@@ -50,14 +46,14 @@ func TestBuild_Prepare(t *testing.T) {
 	packerConfig := testDefaultPackerConfig()
 
 	build := testBuild()
-	builder := build.builder.(*TestBuilder)
+	builder := build.builder.(*MockBuilder)
 
 	build.Prepare(nil)
-	if !builder.prepareCalled {
+	if !builder.PrepareCalled {
 		t.Fatal("should be called")
 	}
-	if !reflect.DeepEqual(builder.prepareConfig, []interface{}{42, packerConfig}) {
-		t.Fatalf("bad: %#v", builder.prepareConfig)
+	if !reflect.DeepEqual(builder.PrepareConfig, []interface{}{42, packerConfig}) {
+		t.Fatalf("bad: %#v", builder.PrepareConfig)
 	}
 
 	coreProv := build.provisioners[0]
@@ -81,7 +77,11 @@ func TestBuild_Prepare(t *testing.T) {
 
 func TestBuild_Prepare_Twice(t *testing.T) {
 	build := testBuild()
-	if err := build.Prepare(nil); err != nil {
+	warn, err := build.Prepare(nil)
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
+	if err != nil {
 		t.Fatalf("bad error: %s", err)
 	}
 
@@ -99,20 +99,36 @@ func TestBuild_Prepare_Twice(t *testing.T) {
 	build.Prepare(nil)
 }
 
+func TestBuildPrepare_BuilderWarniings(t *testing.T) {
+	expected := []string{"foo"}
+
+	build := testBuild()
+	builder := build.builder.(*MockBuilder)
+	builder.PrepareWarnings = expected
+
+	warn, err := build.Prepare(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if !reflect.DeepEqual(warn, expected) {
+		t.Fatalf("bad: %#v", warn)
+	}
+}
+
 func TestBuild_Prepare_Debug(t *testing.T) {
 	packerConfig := testDefaultPackerConfig()
 	packerConfig[DebugConfigKey] = true
 
 	build := testBuild()
-	builder := build.builder.(*TestBuilder)
+	builder := build.builder.(*MockBuilder)
 
 	build.SetDebug(true)
 	build.Prepare(nil)
-	if !builder.prepareCalled {
+	if !builder.PrepareCalled {
 		t.Fatalf("should be called")
 	}
-	if !reflect.DeepEqual(builder.prepareConfig, []interface{}{42, packerConfig}) {
-		t.Fatalf("bad: %#v", builder.prepareConfig)
+	if !reflect.DeepEqual(builder.PrepareConfig, []interface{}{42, packerConfig}) {
+		t.Fatalf("bad: %#v", builder.PrepareConfig)
 	}
 
 	coreProv := build.provisioners[0]
@@ -133,19 +149,22 @@ func TestBuildPrepare_variables_default(t *testing.T) {
 
 	build := testBuild()
 	build.variables["foo"] = coreBuildVariable{Default: "bar"}
-	builder := build.builder.(*TestBuilder)
+	builder := build.builder.(*MockBuilder)
 
-	err := build.Prepare(nil)
+	warn, err := build.Prepare(nil)
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
 
-	if !builder.prepareCalled {
+	if !builder.PrepareCalled {
 		t.Fatal("prepare should be called")
 	}
 
-	if !reflect.DeepEqual(builder.prepareConfig[1], packerConfig) {
-		t.Fatalf("prepare bad: %#v", builder.prepareConfig[1])
+	if !reflect.DeepEqual(builder.PrepareConfig[1], packerConfig) {
+		t.Fatalf("prepare bad: %#v", builder.PrepareConfig[1])
 	}
 }
 
@@ -153,7 +172,10 @@ func TestBuildPrepare_variables_nonexist(t *testing.T) {
 	build := testBuild()
 	build.variables["foo"] = coreBuildVariable{Default: "bar"}
 
-	err := build.Prepare(map[string]string{"bar": "baz"})
+	warn, err := build.Prepare(map[string]string{"bar": "baz"})
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
 	if err == nil {
 		t.Fatal("should have had error")
 	}
@@ -167,19 +189,22 @@ func TestBuildPrepare_variables_override(t *testing.T) {
 
 	build := testBuild()
 	build.variables["foo"] = coreBuildVariable{Default: "bar"}
-	builder := build.builder.(*TestBuilder)
+	builder := build.builder.(*MockBuilder)
 
-	err := build.Prepare(map[string]string{"foo": "baz"})
+	warn, err := build.Prepare(map[string]string{"foo": "baz"})
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
 
-	if !builder.prepareCalled {
+	if !builder.PrepareCalled {
 		t.Fatal("prepare should be called")
 	}
 
-	if !reflect.DeepEqual(builder.prepareConfig[1], packerConfig) {
-		t.Fatalf("prepare bad: %#v", builder.prepareConfig[1])
+	if !reflect.DeepEqual(builder.PrepareConfig[1], packerConfig) {
+		t.Fatalf("prepare bad: %#v", builder.PrepareConfig[1])
 	}
 }
 
@@ -187,7 +212,10 @@ func TestBuildPrepare_variablesRequired(t *testing.T) {
 	build := testBuild()
 	build.variables["foo"] = coreBuildVariable{Required: true}
 
-	err := build.Prepare(map[string]string{})
+	warn, err := build.Prepare(map[string]string{})
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
 	if err == nil {
 		t.Fatal("should have had error")
 	}
@@ -195,7 +223,10 @@ func TestBuildPrepare_variablesRequired(t *testing.T) {
 	// Test with setting the value
 	build = testBuild()
 	build.variables["foo"] = coreBuildVariable{Required: true}
-	err = build.Prepare(map[string]string{"foo": ""})
+	warn, err = build.Prepare(map[string]string{"foo": ""})
+	if len(warn) > 0 {
+		t.Fatalf("bad: %#v", warn)
+	}
 	if err != nil {
 		t.Fatalf("should not have error: %s", err)
 	}
@@ -216,13 +247,13 @@ func TestBuild_Run(t *testing.T) {
 	}
 
 	// Verify builder was run
-	builder := build.builder.(*TestBuilder)
-	if !builder.runCalled {
+	builder := build.builder.(*MockBuilder)
+	if !builder.RunCalled {
 		t.Fatal("should be called")
 	}
 
 	// Verify hooks are disapatchable
-	dispatchHook := builder.runHook
+	dispatchHook := builder.RunHook
 	dispatchHook.Run("foo", nil, nil, 42)
 
 	hook := build.hooks["foo"][0].(*MockHook)
@@ -402,8 +433,8 @@ func TestBuild_Cancel(t *testing.T) {
 	build := testBuild()
 	build.Cancel()
 
-	builder := build.builder.(*TestBuilder)
-	if !builder.cancelCalled {
+	builder := build.builder.(*MockBuilder)
+	if !builder.CancelCalled {
 		t.Fatal("cancel should be called")
 	}
 }

packer/builder.go

@@ -22,7 +22,10 @@ type Builder interface {
 	//
 	// Each of the configuration values should merge into the final
 	// configuration.
-	Prepare(...interface{}) error
+	//
+	// Prepare should return a list of warnings along with any errors
+	// that occured while preparing.
+	Prepare(...interface{}) ([]string, error)
 
 	// Run is where the actual build should take place. It takes a Build and a Ui.
 	Run(ui Ui, hook Hook, cache Cache) (Artifact, error)

packer/builder_mock.go

@@ -4,7 +4,8 @@ package packer
 // You can set some fake return values and you can keep track of what
 // methods were called on the builder. It is fairly basic.
 type MockBuilder struct {
-	ArtifactId string
+	ArtifactId      string
+	PrepareWarnings []string
 
 	PrepareCalled bool
 	PrepareConfig []interface{}
@@ -15,10 +16,10 @@ type MockBuilder struct {
 	CancelCalled  bool
 }
 
-func (tb *MockBuilder) Prepare(config ...interface{}) error {
+func (tb *MockBuilder) Prepare(config ...interface{}) ([]string, error) {
 	tb.PrepareCalled = true
 	tb.PrepareConfig = config
-	return nil
+	return tb.PrepareWarnings, nil
 }
 
 func (tb *MockBuilder) Run(ui Ui, h Hook, c Cache) (Artifact, error) {

packer/builder_test.go

 package packer
-
-type TestBuilder struct {
-	artifactId string
-
-	prepareCalled bool
-	prepareConfig []interface{}
-	runCalled     bool
-	runCache      Cache
-	runHook       Hook
-	runUi         Ui
-	cancelCalled  bool
-}
-
-func (tb *TestBuilder) Prepare(config ...interface{}) error {
-	tb.prepareCalled = true
-	tb.prepareConfig = config
-	return nil
-}
-
-func (tb *TestBuilder) Run(ui Ui, h Hook, c Cache) (Artifact, error) {
-	tb.runCalled = true
-	tb.runHook = h
-	tb.runUi = ui
-	tb.runCache = c
-	return &TestArtifact{id: tb.artifactId}, nil
-}
-
-func (tb *TestBuilder) Cancel() {
-	tb.cancelCalled = true
-}

packer/environment_test.go

@@ -17,7 +17,7 @@ func init() {
 }
 
 func testComponentFinder() *ComponentFinder {
-	builderFactory := func(n string) (Builder, error) { return testBuilder(), nil }
+	builderFactory := func(n string) (Builder, error) { return new(MockBuilder), nil }
 	ppFactory := func(n string) (PostProcessor, error) { return new(TestPostProcessor), nil }
 	provFactory := func(n string) (Provisioner, error) { return new(MockProvisioner), nil }
 	return &ComponentFinder{
@@ -97,7 +97,7 @@ func TestEnvironment_NilComponents(t *testing.T) {
 }
 
 func TestEnvironment_Builder(t *testing.T) {
-	builder := &TestBuilder{}
+	builder := &MockBuilder{}
 	builders := make(map[string]Builder)
 	builders["foo"] = builder
 

packer/template_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func testTemplateComponentFinder() *ComponentFinder {
-	builder := testBuilder()
+	builder := new(MockBuilder)
 	pp := new(TestPostProcessor)
 	provisioner := &MockProvisioner{}
 
@@ -706,7 +706,7 @@ func TestTemplate_Build(t *testing.T) {
 		t.Fatalf("err: %s", err)
 	}
 
-	builder := testBuilder()
+	builder := new(MockBuilder)
 	builderMap := map[string]Builder{
 		"test-builder": builder,
 	}
@@ -1194,7 +1194,7 @@ func TestTemplate_Build_ProvisionerOverride(t *testing.T) {
 		t.Fatalf("bad raw: %#v", RawConfig)
 	}
 
-	builder := testBuilder()
+	builder := new(MockBuilder)
 	builderMap := map[string]Builder{
 		"test-builder": builder,
 	}