Issue #273 - Template refactor to resolve suggestions in PR #341

Author: mneil

common/decorator_test.go

@@ -29,7 +29,7 @@ Resources:
 	err := yaml.Unmarshal([]byte(overridesYaml), overrides)
 	assert.Nil(err)
 
-	templateBody, err := templates.GetAsset(TemplateBucket, templates.AddData(nil))
+	templateBody, err := templates.GetAsset(TemplateBucket, templates.ExecuteTemplate(nil))
 	assert.Nil(err)
 	assert.NotNil(templateBody)
 

provider/aws/cloudformation.go

@@ -287,7 +287,7 @@ func (cfnMgr *cloudformationStackManager) UpsertStack(stackName string, template
 	}
 
 	// load the template
-	templateBody, err := templates.GetAsset(templateName, templates.AddData(templateData),
+	templateBody, err := templates.GetAsset(templateName, templates.ExecuteTemplate(templateData),
 		templates.DecorateTemplate(cfnMgr.extensionsManager, stackName))
 	templateBodyBytes := bytes.NewBufferString(templateBody)
 

provider/aws/cloudformation_test.go

@@ -565,7 +565,7 @@ func mockNilExtensionManager() *mockedExtensionsManager {
 
 func mockTemplateBody(extMgr *mockedExtensionsManager, stackName string, templateName string, templateData interface{}) *string {
 
-	templateBody, _ := templates.GetAsset(templateName, templates.AddData(templateData),
+	templateBody, _ := templates.GetAsset(templateName, templates.ExecuteTemplate(templateData),
 		templates.DecorateTemplate(extMgr, stackName))
 
 	return aws.String(templateBody)

templates/template.go

@@ -8,77 +8,76 @@ import (
 	"io"
 	"text/template"
 
-	"github.com/aws/aws-sdk-go/aws"
 	"github.com/gobuffalo/packr"
 )
 
 // GetAsset reads an asset from "disk" into a string
-func GetAsset(assetName string, options ...func(string, *string) error) (string, error) {
+func GetAsset(assetName string, options ...AssetOption) (string, error) {
 	box := packr.NewBox("./assets")
 
 	asset, err := box.MustString(assetName)
 	if err != nil {
 		return "", err
 	}
-	assetRef := aws.String(asset)
 
 	for _, option := range options {
-		if err := option(assetName, assetRef); err != nil {
+		if asset, err = option(assetName, asset); err != nil {
 			return "", err
 		}
 	}
 
-	return *assetRef, nil
+	return asset, nil
 }
 
-// AddData adds the data parameter to a text/template
-func AddData(data interface{}) func(string, *string) error {
-	return func(assetName string, asset *string) error {
+// ExecuteTemplate executes the data parameter on a text/template
+func ExecuteTemplate(data interface{}) AssetOption {
+	return func(assetName string, asset string) (string, error) {
 
-		tmpl, err := template.New(assetName).Parse(*asset)
+		tmpl, err := template.New(assetName).Parse(asset)
 		if err != nil {
-			return err
+			return asset, err
 		}
 
 		buf := new(bytes.Buffer)
 		bufWriter := bufio.NewWriter(buf)
 
 		err = tmpl.Execute(bufWriter, data)
 		if err != nil {
-			return err
+			return asset, err
 		}
 
 		bufWriter.Flush()
 
 		templateBodyBytes := new(bytes.Buffer)
 		_, err = templateBodyBytes.ReadFrom(buf)
 		if err != nil {
-			return err
+			return asset, err
 		}
-		*asset = templateBodyBytes.String()
 
-		return nil
+		return templateBodyBytes.String(), nil
 	}
 }
 
 // DecorateTemplate uses an ExtensionImpl to inject data into an extension
-func DecorateTemplate(extMgr decoratorImpl,
-	stackName string) func(string, *string) error {
-	return func(assetName string, asset *string) error {
-		assetBuf := bytes.NewBufferString(*asset)
+func DecorateTemplate(extMgr StackTemplateDecorator,
+	stackName string) AssetOption {
+	return func(assetName string, asset string) (string, error) {
+		assetBuf := bytes.NewBufferString(asset)
 		if _, err := extMgr.DecorateStackTemplate(assetName, stackName, assetBuf); err != nil {
-			return err
+			return "", err
 		}
 		templateBodyBytes := new(bytes.Buffer)
 		if _, err := templateBodyBytes.ReadFrom(assetBuf); err != nil {
-			return err
+			return "", err
 		}
-		*asset = templateBodyBytes.String()
-		return nil
+		return templateBodyBytes.String(), nil
 	}
 }
 
-// stub for decorate template struct to avoid circular dependencies
-type decoratorImpl interface {
+// AssetOption describes the method signature for manipulating loaded assets
+type AssetOption func(string, string) (string, error)
+
+// StackTemplateDecorator is a stub for decorate template struct to avoid circular dependencies
+type StackTemplateDecorator interface {
 	DecorateStackTemplate(assetName string, stackName string, templateBody io.Reader) (io.Reader, error)
 }

templates/template_test.go

@@ -58,7 +58,7 @@ func TestNewTemplate_assets(t *testing.T) {
 			continue
 		}
 
-		templateBody, err := GetAsset(templateName, AddData(nil))
+		templateBody, err := GetAsset(templateName, ExecuteTemplate(nil))
 
 		assert.Nil(err, templateName)
 		assert.NotNil(templateBody, templateName)
@@ -81,12 +81,11 @@ func TestNewTemplate_assets(t *testing.T) {
 				}
 				assert.Fail(err.Error(), templateName)
 			}
-
 		}
 	}
 }
 
-func TestAddData(t *testing.T) {
+func TestExecuteTemplate(t *testing.T) {
 	assert := assert.New(t)
 
 	sessOptions := session.Options{SharedConfigState: session.SharedConfigEnable}
@@ -95,7 +94,7 @@ func TestAddData(t *testing.T) {
 
 	svc := cloudformation.New(sess)
 
-	templateBody, err := GetAsset(common.TemplateServiceEC2, AddData(nil))
+	templateBody, err := GetAsset(common.TemplateServiceEC2, ExecuteTemplate(nil))
 
 	assert.NotNil(templateBody)
 	assert.NotEmpty(templateBody)

workflows/config_init.go

@@ -78,7 +78,7 @@ func (workflow *configWorkflow) configInitialize(config *common.Config, createEn
 
 		// write buildspec
 		buildspec, err := templates.GetAsset(common.TemplateBuildspec,
-			templates.AddData(nil))
+			templates.ExecuteTemplate(nil))
 		if err != nil {
 			return err
 		}

workflows/pipeline_upsert.go

@@ -269,7 +269,7 @@ func PipelineParams(workflow *pipelineWorkflow, namespace string, params map[str
 
 	// get default buildspec
 	buildspec, err := templates.GetAsset(common.TemplateBuildspec,
-		templates.AddData(nil))
+		templates.ExecuteTemplate(nil))
 	if err != nil {
 		return nil, err
 	}