mdatagen: get package name from metadata

I noticed a mistake in my previous PR #11232; some function calls did
not pass the correct package name in (passing in "metadata" instead of
the intended generated package name). This PR attempts to address the
potential for this mistake to even occur by providing a wrapper
`generateFile` function that automatically uses the generated package
name from the metadata. The original version of the function that
accepts a package name is intact for the templates that are going in the
base package instead of the generated one.

Makefile

@@ -539,3 +539,4 @@ mdatagen-test:
 	cd cmd/mdatagen && $(GOCMD) install .
 	cd cmd/mdatagen && $(GOCMD) generate ./...
 	cd cmd/mdatagen && $(GOCMD) test ./...
+	$(MAKE) -C cmd/mdatagen fmt

cmd/mdatagen/internal/command.go

@@ -81,16 +81,16 @@ func run(ymlPath string) error {
 	if md.Status != nil {
 		if md.Status.Class != "cmd" && md.Status.Class != "pkg" && !md.Status.NotComponent {
 			if err = generateFile(filepath.Join(tmplDir, "status.go.tmpl"),
-				filepath.Join(codeDir, "generated_status.go"), md, "metadata"); err != nil {
+				filepath.Join(codeDir, "generated_status.go"), md); err != nil {
 				return err
 			}
-			if err = generateFile(filepath.Join(tmplDir, "component_test.go.tmpl"),
+			if err = generateFileWithPackageName(filepath.Join(tmplDir, "component_test.go.tmpl"),
 				filepath.Join(ymlDir, "generated_component_test.go"), md, packageName); err != nil {
 				return err
 			}
 		}
 
-		if err = generateFile(filepath.Join(tmplDir, "package_test.go.tmpl"),
+		if err = generateFileWithPackageName(filepath.Join(tmplDir, "package_test.go.tmpl"),
 			filepath.Join(ymlDir, "generated_package_test.go"), md, packageName); err != nil {
 			return err
 		}
@@ -108,7 +108,7 @@ func run(ymlPath string) error {
 	toGenerate := map[string]string{}
 
 	if len(md.Telemetry.Metrics) != 0 { // if there are telemetry metrics, generate telemetry specific files
-		if err = generateFile(filepath.Join(tmplDir, "component_telemetry_test.go.tmpl"),
+		if err = generateFileWithPackageName(filepath.Join(tmplDir, "component_telemetry_test.go.tmpl"),
 			filepath.Join(ymlDir, "generated_component_telemetry_test.go"), md, packageName); err != nil {
 			return err
 		}
@@ -121,7 +121,7 @@ func run(ymlPath string) error {
 	}
 
 	for tmpl, dst := range toGenerate {
-		if err = generateFile(tmpl, dst, md, "metadata"); err != nil {
+		if err = generateFile(tmpl, dst, md); err != nil {
 			return err
 		}
 	}
@@ -151,7 +151,7 @@ func run(ymlPath string) error {
 	}
 
 	for tmpl, dst := range toGenerate {
-		if err = generateFile(tmpl, dst, md, md.GeneratedPackageName); err != nil {
+		if err = generateFile(tmpl, dst, md); err != nil {
 			return err
 		}
 	}
@@ -400,7 +400,11 @@ func inlineReplace(tmplFile string, outputFile string, md Metadata, start string
 	return nil
 }
 
-func generateFile(tmplFile string, outputFile string, md Metadata, goPackage string) error {
+func generateFile(tmplFile string, outputFile string, md Metadata) error {
+	return generateFileWithPackageName(tmplFile, outputFile, md, md.GeneratedPackageName)
+}
+
+func generateFileWithPackageName(tmplFile string, outputFile string, md Metadata, goPackage string) error {
 	if err := os.Remove(outputFile); err != nil && !errors.Is(err, os.ErrNotExist) {
 		return fmt.Errorf("unable to remove generated file %q: %w", outputFile, err)
 	}

cmd/mdatagen/internal/command_test.go

@@ -501,7 +501,8 @@ func TestGenerateStatusMetadata(t *testing.T) {
 		{
 			name: "foo component with beta status",
 			md: Metadata{
-				Type: "foo",
+				Type:                 "foo",
+				GeneratedPackageName: "metadata",
 				Status: &Status{
 					Stability: map[component.StabilityLevel][]string{
 						component.StabilityLevelBeta: {"metrics"},
@@ -531,7 +532,8 @@ const (
 		{
 			name: "foo component with alpha status",
 			md: Metadata{
-				Type: "foo",
+				Type:                 "foo",
+				GeneratedPackageName: "metadata",
 				Status: &Status{
 					Stability: map[component.StabilityLevel][]string{
 						component.StabilityLevelAlpha: {"metrics"},
@@ -564,7 +566,7 @@ const (
 		t.Run(tt.name, func(t *testing.T) {
 			tmpdir := t.TempDir()
 			err := generateFile("templates/status.go.tmpl",
-				filepath.Join(tmpdir, "generated_status.go"), tt.md, "metadata")
+				filepath.Join(tmpdir, "generated_status.go"), tt.md)
 			require.NoError(t, err)
 			actual, err := os.ReadFile(filepath.Join(tmpdir, "generated_status.go")) // nolint: gosec
 			require.NoError(t, err)
@@ -583,7 +585,8 @@ func TestGenerateTelemetryMetadata(t *testing.T) {
 		{
 			name: "foo component with beta status",
 			md: Metadata{
-				Type: "foo",
+				Type:                 "foo",
+				GeneratedPackageName: "metadata",
 				Status: &Status{
 					Stability: map[component.StabilityLevel][]string{
 						component.StabilityLevelBeta: {"metrics"},
@@ -621,7 +624,8 @@ func Tracer(settings component.TelemetrySettings) trace.Tracer {
 		{
 			name: "foo component with alpha status",
 			md: Metadata{
-				Type: "foo",
+				Type:                 "foo",
+				GeneratedPackageName: "metadata",
 				Status: &Status{
 					Stability: map[component.StabilityLevel][]string{
 						component.StabilityLevelAlpha: {"metrics"},
@@ -662,7 +666,7 @@ func Tracer(settings component.TelemetrySettings) trace.Tracer {
 		t.Run(tt.name, func(t *testing.T) {
 			tmpdir := t.TempDir()
 			err := generateFile("templates/telemetry.go.tmpl",
-				filepath.Join(tmpdir, "generated_telemetry.go"), tt.md, "metadata")
+				filepath.Join(tmpdir, "generated_telemetry.go"), tt.md)
 			require.NoError(t, err)
 			actual, err := os.ReadFile(filepath.Join(tmpdir, "generated_telemetry.go")) // nolint: gosec
 			require.NoError(t, err)

cmd/mdatagen/internal/sampleprocessor/doc.go

@@ -3,6 +3,7 @@
 
 // Generate a test metrics builder from a sample metrics set covering all configuration options.
 //go:generate mdatagen metadata.yaml
+//go:generate mdatagen metadata_custom.yaml
 
 // Deprecated: This package is moving to https://github.com/open-telemetry/opentelemetry-collector and will eventually be removed.
 // Please see https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/30497