add resolver

cmd/bundle/init.go

@@ -1,40 +1,15 @@
 package bundle
 
 import (
-	"context"
 	"errors"
 	"fmt"
-	"path/filepath"
-	"strings"
 
 	"github.com/databricks/cli/cmd/root"
 	"github.com/databricks/cli/libs/cmdio"
-	"github.com/databricks/cli/libs/dbr"
-	"github.com/databricks/cli/libs/filer"
 	"github.com/databricks/cli/libs/template"
 	"github.com/spf13/cobra"
 )
 
-func constructOutputFiler(ctx context.Context, outputDir string) (filer.Filer, error) {
-	outputDir, err := filepath.Abs(outputDir)
-	if err != nil {
-		return nil, err
-	}
-
-	// If the CLI is running on DBR and we're writing to the workspace file system,
-	// use the extension-aware workspace filesystem filer to instantiate the template.
-	//
-	// It is not possible to write notebooks through the workspace filesystem's FUSE mount.
-	// Therefore this is the only way we can initialize templates that contain notebooks
-	// when running the CLI on DBR and initializing a template to the workspace.
-	//
-	if strings.HasPrefix(outputDir, "/Workspace/") && dbr.RunsOnRuntime(ctx) {
-		return filer.NewWorkspaceFilesExtensionsClient(root.WorkspaceClient(ctx), outputDir)
-	}
-
-	return filer.NewLocalClient(outputDir)
-}
-
 func newInitCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "init [TEMPLATE_PATH]",
@@ -62,35 +37,18 @@ See https://docs.databricks.com/en/dev-tools/bundles/templates.html for more inf
 	cmd.Flags().StringVar(&tag, "branch", "", "Git branch to use for template initialization")
 
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
-		if tag != "" && branch != "" {
+		r := template.Resolver{
-			return errors.New("only one of --tag or --branch can be specified")
+			TemplatePathOrUrl: args[0],
+			ConfigFile:        configFile,
+			OutputDir:         outputDir,
+			TemplateDir:       templateDir,
+			Tag:               tag,
+			Branch:            branch,
 		}
 
-		// Git ref to use for template initialization
-		ref := branch
-		if tag != "" {
-			ref = tag
-		}
-
-		var tmpl *template.Template
-		var err error
 		ctx := cmd.Context()
-
+		tmpl, err := r.Resolve(ctx)
-		if len(args) > 0 {
+		if errors.Is(err, template.ErrCustomSelected) {
-			// User already specified a template local path or a Git URL. Use that
-			// information to configure a reader for the template
-			tmpl = template.Get(template.Custom)
-			// TODO: Get rid of the name arg.
-			if template.IsGitRepoUrl(args[0]) {
-				tmpl.SetReader(template.NewGitReader("", args[0], ref, templateDir))
-			} else {
-				tmpl.SetReader(template.NewLocalReader("", args[0]))
-			}
-		} else {
-			tmplId, err := template.PromptForTemplateId(cmd.Context(), ref, templateDir)
-			if tmplId == template.Custom {
-				// If a user selects custom during the prompt, ask them to provide a path or Git URL
-				// as a positional argument.
 			cmdio.LogString(ctx, "Please specify a path or Git repository to use a custom template.")
 			cmdio.LogString(ctx, "See https://docs.databricks.com/en/dev-tools/bundles/templates.html to learn more about custom templates.")
 			return nil
@@ -98,25 +56,9 @@ See https://docs.databricks.com/en/dev-tools/bundles/templates.html for more inf
 		if err != nil {
 			return err
 		}
-
-			tmpl = template.Get(tmplId)
-		}
-
 		defer tmpl.Reader.Close()
 
-		outputFiler, err := constructOutputFiler(ctx, outputDir)
+		return tmpl.Writer.Materialize(ctx, tmpl.Reader)
-		if err != nil {
-			return err
-		}
-
-		tmpl.Writer.Initialize(tmpl.Reader, configFile, outputFiler)
-
-		err = tmpl.Writer.Materialize(ctx)
-		if err != nil {
-			return err
-		}
-
-		return tmpl.Writer.LogTelemetry(ctx)
 	}
 	return cmd
 }

libs/template/reader.go

@@ -21,12 +21,10 @@ type Reader interface {
 	// Close releases any resources associated with the reader
 	// like cleaning up temporary directories.
 	Close() error
-
-	Name() string
 }
 
 type builtinReader struct {
-	name     string
+	name     TemplateName
 	fsCached fs.FS
 }
 
@@ -43,7 +41,7 @@ func (r *builtinReader) FS(ctx context.Context) (fs.FS, error) {
 
 	var templateFS fs.FS
 	for _, entry := range builtin {
-		if entry.Name == r.name {
+		if entry.Name == string(r.name) {
 			templateFS = entry.FS
 			break
 		}
@@ -57,13 +55,7 @@ func (r *builtinReader) Close() error {
 	return nil
 }
 
-func (r *builtinReader) Name() string {
-	return r.name
-}
-
 type gitReader struct {
-	name string
-	// URL of the git repository that contains the template
 	gitUrl string
 	// tag or branch to checkout
 	ref string
@@ -88,7 +80,7 @@ var gitUrlPrefixes = []string{
 	"git@",
 }
 
-// TODO: Copy over tests for this function.
+// TODO: Make private?
 func IsGitRepoUrl(url string) bool {
 	result := false
 	for _, prefix := range gitUrlPrefixes {
@@ -100,16 +92,6 @@ func IsGitRepoUrl(url string) bool {
 	return result
 }
 
-// TODO: Can I remove the name from here and other readers?
-func NewGitReader(name, gitUrl, ref, templateDir string) Reader {
-	return &gitReader{
-		name:        name,
-		gitUrl:      gitUrl,
-		ref:         ref,
-		templateDir: templateDir,
-	}
-}
-
 // TODO: Test the idempotency of this function as well.
 func (r *gitReader) FS(ctx context.Context) (fs.FS, error) {
 	// If the FS has already been loaded, return it.
@@ -147,10 +129,6 @@ func (r *gitReader) Close() error {
 	return os.RemoveAll(r.tmpRepoDir)
 }
 
-func (r *gitReader) Name() string {
-	return r.name
-}
-
 type localReader struct {
 	name string
 	// Path on the local filesystem that contains the template
@@ -159,13 +137,6 @@ type localReader struct {
 	fsCached fs.FS
 }
 
-func NewLocalReader(name, path string) Reader {
-	return &localReader{
-		name: name,
-		path: path,
-	}
-}
-
 func (r *localReader) FS(ctx context.Context) (fs.FS, error) {
 	// If the FS has already been loaded, return it.
 	if r.fsCached != nil {
@@ -180,10 +151,6 @@ func (r *localReader) Close() error {
 	return nil
 }
 
-func (r *localReader) Name() string {
-	return r.name
-}
-
 type failReader struct{}
 
 func (r *failReader) FS(ctx context.Context) (fs.FS, error) {
@@ -193,7 +160,3 @@ func (r *failReader) FS(ctx context.Context) (fs.FS, error) {
 func (r *failReader) Close() error {
 	return fmt.Errorf("this is a placeholder reader that always fails. Please configure a real reader.")
 }
-
-func (r *failReader) Name() string {
-	return "failReader"
-}

libs/template/resolve.go

@@ -0,0 +1,70 @@
+package template
+
+import (
+	"context"
+	"errors"
+)
+
+type Resolver struct {
+	TemplatePathOrUrl string
+	ConfigFile        string
+	OutputDir         string
+	TemplateDir       string
+	Tag               string
+	Branch            string
+}
+
+var ErrCustomSelected = errors.New("custom template selected")
+
+// Configures the reader and the writer for template and returns
+// a handle to the template.
+// Prompts the user if needed.
+func (r Resolver) Resolve(ctx context.Context) (*Template, error) {
+	if r.Tag != "" && r.Branch != "" {
+		return nil, errors.New("only one of --tag or --branch can be specified")
+	}
+
+	// Git ref to use for template initialization
+	ref := r.Branch
+	if r.Tag != "" {
+		ref = r.Tag
+	}
+
+	var tmpl *Template
+	if r.TemplatePathOrUrl == "" {
+		// Prompt the user to select a template
+		// if a template path or URL is not provided.
+		tmplId, err := SelectTemplate(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		if tmplId == Custom {
+			return nil, ErrCustomSelected
+		}
+
+		tmpl = Get(tmplId)
+	} else {
+		// Based on the provided template path or URL,
+		// configure a reader for the template.
+		tmpl = Get(Custom)
+		if IsGitRepoUrl(r.TemplatePathOrUrl) {
+			tmpl.Reader = &gitReader{
+				gitUrl:      r.TemplatePathOrUrl,
+				ref:         ref,
+				templateDir: r.TemplateDir,
+			}
+		} else {
+			tmpl.Reader = &localReader{
+				path: r.TemplatePathOrUrl,
+			}
+		}
+	}
+
+	err := tmpl.Writer.Configure(ctx, r.ConfigFile, r.OutputDir)
+	if err != nil {
+		return nil, err
+	}
+
+	return tmpl, nil
+}

libs/template/template.go

@@ -6,14 +6,14 @@ import (
 	"strings"
 
 	"github.com/databricks/cli/libs/cmdio"
-	"github.com/databricks/cli/libs/filer"
 )
 
 type Template struct {
+	// TODO: Make private as much as possible.
 	Reader Reader
 	Writer Writer
 
-	Id          TemplateId
+	Name        TemplateName
 	Description string
 	Aliases     []string
 	Hidden      bool
@@ -30,52 +30,52 @@ type NativeTemplate struct {
 	IsOwnedByDatabricks bool
 }
 
-type TemplateId string
+type TemplateName string
 
 const (
-	DefaultPython TemplateId = "default-python"
+	DefaultPython TemplateName = "default-python"
-	DefaultSql    TemplateId = "default-sql"
+	DefaultSql    TemplateName = "default-sql"
-	DbtSql        TemplateId = "dbt-sql"
+	DbtSql        TemplateName = "dbt-sql"
-	MlopsStacks   TemplateId = "mlops-stacks"
+	MlopsStacks   TemplateName = "mlops-stacks"
-	DefaultPydabs TemplateId = "default-pydabs"
+	DefaultPydabs TemplateName = "default-pydabs"
-	Custom        TemplateId = "custom"
+	Custom        TemplateName = "custom"
 )
 
 var allTemplates = []Template{
 	{
-		Id:          DefaultPython,
+		Name:        DefaultPython,
 		Description: "The default Python template for Notebooks / Delta Live Tables / Workflows",
 		Reader:      &builtinReader{name: "default-python"},
 		Writer:      &writerWithTelemetry{},
 	},
 	{
-		Id:          DefaultSql,
+		Name:        DefaultSql,
 		Description: "The default SQL template for .sql files that run with Databricks SQL",
 		Reader:      &builtinReader{name: "default-sql"},
 		Writer:      &writerWithTelemetry{},
 	},
 	{
-		Id:          DbtSql,
+		Name:        DbtSql,
 		Description: "The dbt SQL template (databricks.com/blog/delivering-cost-effective-data-real-time-dbt-and-databricks)",
 		Reader:      &builtinReader{name: "dbt-sql"},
 		Writer:      &writerWithTelemetry{},
 	},
 	{
-		Id:          MlopsStacks,
+		Name:        MlopsStacks,
 		Description: "The Databricks MLOps Stacks template (github.com/databricks/mlops-stacks)",
 		Aliases:     []string{"mlops-stack"},
 		Reader:      &gitReader{gitUrl: "https://github.com/databricks/mlops-stacks"},
 		Writer:      &writerWithTelemetry{},
 	},
 	{
-		Id:          DefaultPydabs,
+		Name:        DefaultPydabs,
 		Hidden:      true,
 		Description: "The default PyDABs template",
 		Reader:      &gitReader{gitUrl: "https://databricks.github.io/workflows-authoring-toolkit/pydabs-template.git"},
 		Writer:      &writerWithTelemetry{},
 	},
 	{
-		Id:          Custom,
+		Name:        Custom,
 		Description: "Bring your own template",
 		Reader:      &failReader{},
 		Writer:      &defaultWriter{},
@@ -85,8 +85,8 @@ var allTemplates = []Template{
 func HelpDescriptions() string {
 	var lines []string
 	for _, template := range allTemplates {
-		if template.Id != Custom && !template.Hidden {
+		if template.Name != Custom && !template.Hidden {
-			lines = append(lines, fmt.Sprintf("- %s: %s", template.Id, template.Description))
+			lines = append(lines, fmt.Sprintf("- %s: %s", template.Name, template.Description))
 		}
 	}
 	return strings.Join(lines, "\n")
@@ -99,7 +99,7 @@ func options() []cmdio.Tuple {
 			continue
 		}
 		tuple := cmdio.Tuple{
-			Name: string(template.Id),
+			Name: string(template.Name),
 			Id:   template.Description,
 		}
 		names = append(names, tuple)
@@ -108,7 +108,7 @@ func options() []cmdio.Tuple {
 }
 
 // TODO CONTINUE defining the methods that the init command will finally rely on.
-func PromptForTemplateId(ctx context.Context, ref, templateDir string) (TemplateId, error) {
+func SelectTemplate(ctx context.Context) (TemplateName, error) {
 	if !cmdio.IsPromptSupported(ctx) {
 		return "", fmt.Errorf("please specify a template")
 	}
@@ -119,24 +119,16 @@ func PromptForTemplateId(ctx context.Context, ref, templateDir string) (Template
 
 	for _, template := range allTemplates {
 		if template.Description == description {
-			return template.Id, nil
+			return template.Name, nil
 		}
 	}
 
 	panic("this should never happen - template not found")
 }
 
-func (tmpl *Template) InitializeWriter(configPath string, outputFiler filer.Filer) {
+func Get(name TemplateName) *Template {
-	tmpl.Writer.Initialize(tmpl.Reader, configPath, outputFiler)
-}
-
-func (tmpl *Template) SetReader(r Reader) {
-	tmpl.Reader = r
-}
-
-func Get(id TemplateId) *Template {
 	for _, template := range allTemplates {
-		if template.Id == id {
+		if template.Name == name {
 			return &template
 		}
 	}

libs/template/writer.go

@@ -5,8 +5,12 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
+	"path/filepath"
+	"strings"
 
+	"github.com/databricks/cli/cmd/root"
 	"github.com/databricks/cli/libs/cmdio"
+	"github.com/databricks/cli/libs/dbr"
 	"github.com/databricks/cli/libs/filer"
 )
 
@@ -30,7 +34,6 @@ import (
 // 	assert.EqualError(t, err, fmt.Sprintf("not a bundle template: expected to find a template schema file at %s", schemaFileName))
 // }
 
-
 // TODO: Add tests for these writers, mocking the cmdio library
 // at the same time.
 const (
@@ -40,13 +43,12 @@ const (
 )
 
 type Writer interface {
-	Initialize(reader Reader, configPath string, outputFiler filer.Filer)
+	Configure(ctx context.Context, configPath, outputDir string) error
-	Materialize(ctx context.Context) error
+	Materialize(ctx context.Context, r Reader) error
 	LogTelemetry(ctx context.Context) error
 }
 
 type defaultWriter struct {
-	reader      Reader
 	configPath  string
 	outputFiler filer.Filer
 
@@ -55,13 +57,40 @@ type defaultWriter struct {
 	renderer *renderer
 }
 
-func (tmpl *defaultWriter) Initialize(reader Reader, configPath string, outputFiler filer.Filer) {
+func constructOutputFiler(ctx context.Context, outputDir string) (filer.Filer, error) {
-	tmpl.configPath = configPath
+	outputDir, err := filepath.Abs(outputDir)
-	tmpl.outputFiler = outputFiler
+	if err != nil {
+		return nil, err
+	}
+
+	// If the CLI is running on DBR and we're writing to the workspace file system,
+	// use the extension-aware workspace filesystem filer to instantiate the template.
+	//
+	// It is not possible to write notebooks through the workspace filesystem's FUSE mount.
+	// Therefore this is the only way we can initialize templates that contain notebooks
+	// when running the CLI on DBR and initializing a template to the workspace.
+	//
+	if strings.HasPrefix(outputDir, "/Workspace/") && dbr.RunsOnRuntime(ctx) {
+		return filer.NewWorkspaceFilesExtensionsClient(root.WorkspaceClient(ctx), outputDir)
+	}
+
+	return filer.NewLocalClient(outputDir)
 }
 
-func (tmpl *defaultWriter) promptForInput(ctx context.Context) error {
+func (tmpl *defaultWriter) Configure(ctx context.Context, configPath string, outputDir string) error {
-	readerFs, err := tmpl.reader.FS(ctx)
+	tmpl.configPath = configPath
+
+	outputFiler, err := constructOutputFiler(ctx, outputDir)
+	if err != nil {
+		return err
+	}
+
+	tmpl.outputFiler = outputFiler
+	return nil
+}
+
+func (tmpl *defaultWriter) promptForInput(ctx context.Context, reader Reader) error {
+	readerFs, err := reader.FS(ctx)
 	if err != nil {
 		return err
 	}
@@ -122,8 +151,8 @@ func (tmpl *defaultWriter) printSuccessMessage(ctx context.Context) error {
 	return nil
 }
 
-func (tmpl *defaultWriter) Materialize(ctx context.Context) error {
+func (tmpl *defaultWriter) Materialize(ctx context.Context, reader Reader) error {
-	err := tmpl.promptForInput(ctx)
+	err := tmpl.promptForInput(ctx, reader)
 	if err != nil {
 		return err
 	}
@@ -157,13 +186,3 @@ func (tmpl *writerWithTelemetry) LogTelemetry(ctx context.Context) error {
 	// Log telemetry. TODO.
 	return nil
 }
-
-func NewWriterWithTelemetry(reader Reader, configPath string, outputFiler filer.Filer) Writer {
-	return &writerWithTelemetry{
-		defaultWriter: defaultWriter{
-			reader:      reader,
-			configPath:  configPath,
-			outputFiler: outputFiler,
-		},
-	}
-}