chore(feature): adds context to manifest errors (opendatahub-io#1104)

During processing manifest files the names of the files were not
reported as part of the errors such as missing keys referred in the
templates. This commit adds this context to returned errors so the
problems can be located faster.

(cherry picked from commit 9f02899)

pkg/feature/manifest.go

@@ -33,19 +33,24 @@ type rawManifest struct {
 var _ Manifest = (*rawManifest)(nil)
 
 func (b *rawManifest) Process(_ any) ([]*unstructured.Unstructured, error) {
-	manifestFile, err := b.fsys.Open(b.path)
-	if err != nil {
-		return nil, err
+	manifestFile, openErr := b.fsys.Open(b.path)
+	if openErr != nil {
+		return nil, fmt.Errorf("failed opening file %s: %w", b.path, openErr)
 	}
 	defer manifestFile.Close()
 
-	content, err := io.ReadAll(manifestFile)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read file: %w", err)
+	content, readErr := io.ReadAll(manifestFile)
+	if readErr != nil {
+		return nil, fmt.Errorf("failed to read file %s: %w", b.path, readErr)
 	}
 	resources := string(content)
 
-	return convertToUnstructuredSlice(resources)
+	unstructuredObjs, convertErr := convertToUnstructuredSlice(resources)
+	if convertErr != nil {
+		return nil, fmt.Errorf("failed to convert resources defined in %s to unstructured objects: %w", b.path, convertErr)
+	}
+
+	return unstructuredObjs, nil
 }
 
 func (b *rawManifest) MarkAsManaged(objects []*unstructured.Unstructured) {
@@ -64,33 +69,38 @@ type templateManifest struct {
 }
 
 func (t *templateManifest) Process(data any) ([]*unstructured.Unstructured, error) {
-	manifestFile, err := t.fsys.Open(t.path)
-	if err != nil {
-		return nil, err
+	manifestFile, openErr := t.fsys.Open(t.path)
+	if openErr != nil {
+		return nil, fmt.Errorf("failed opening file %s: %w", t.path, openErr)
 	}
 	defer manifestFile.Close()
 
-	content, err := io.ReadAll(manifestFile)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create file: %w", err)
+	content, readErr := io.ReadAll(manifestFile)
+	if readErr != nil {
+		return nil, fmt.Errorf("failed to read file %s: %w", t.path, readErr)
 	}
 
-	tmpl, err := template.New(t.name).
+	tmpl, parseErr := template.New(t.name).
 		Option("missingkey=error").
 		Funcs(template.FuncMap{"ReplaceChar": ReplaceChar}).
 		Parse(string(content))
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse template: %w", err)
+	if parseErr != nil {
+		return nil, fmt.Errorf("failed to parse template %s: %w", t.path, parseErr)
 	}
 
 	var buffer bytes.Buffer
-	if err := tmpl.Execute(&buffer, data); err != nil {
-		return nil, fmt.Errorf("failed to execute template: %w", err)
+	if executeTmplErr := tmpl.Execute(&buffer, data); executeTmplErr != nil {
+		return nil, fmt.Errorf("failed to execute template %s: %w", t.path, executeTmplErr)
 	}
 
 	resources := buffer.String()
 
-	return convertToUnstructuredSlice(resources)
+	unstructuredObjs, convertErr := convertToUnstructuredSlice(resources)
+	if convertErr != nil {
+		return nil, fmt.Errorf("failed to convert resources defined in %s to unstructured objects: %w", t.path, convertErr)
+	}
+
+	return unstructuredObjs, nil
 }
 
 func (t *templateManifest) MarkAsManaged(objects []*unstructured.Unstructured) {