Merge pull request #13586 from jessesimpson36/cleaner-stacktraces

fix: add formatting for errors to make multiline stacktraces in helm templates

pkg/action/install_test.go

@@ -447,7 +447,9 @@ func TestInstallReleaseIncorrectTemplate_DryRun(t *testing.T) {
 	instAction.DryRun = true
 	vals := map[string]interface{}{}
 	_, err := instAction.Run(buildChart(withSampleIncludingIncorrectTemplates()), vals)
-	expectedErr := "\"hello/templates/incorrect\" at <.Values.bad.doh>: nil pointer evaluating interface {}.doh"
+	expectedErr := `hello/templates/incorrect:1:10
+  executing "hello/templates/incorrect" at <.Values.bad.doh>:
+    nil pointer evaluating interface {}.doh`
 	if err == nil {
 		t.Fatalf("Install should fail containing error: %s", expectedErr)
 	}

pkg/engine/engine.go

@@ -34,6 +34,18 @@ import (
 	chartutil "helm.sh/helm/v4/pkg/chart/v2/util"
 )
 
+// taken from https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=141
+// > "template: %s: executing %q at <%s>: %s"
+var execErrFmt = regexp.MustCompile(`^template: (?P<templateName>(?U).+): executing (?P<functionName>(?U).+) at (?P<location>(?U).+): (?P<errMsg>(?U).+)(?P<nextErr>( template:.*)?)$`)
+
+// taken from https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=138
+// > "template: %s: %s"
+var execErrFmtWithoutTemplate = regexp.MustCompile(`^template: (?P<templateName>(?U).+): (?P<errMsg>.*)(?P<nextErr>( template:.*)?)$`)
+
+// taken from https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=191
+// > "template: no template %q associated with template %q"
+var execErrNoTemplateAssociated = regexp.MustCompile(`^template: no template (?P<location>.*) associated with template (?P<functionName>(.*)?)$`)
+
 // Engine is an implementation of the Helm rendering implementation for templates.
 type Engine struct {
 	// If strict is enabled, template rendering will fail if a template references
@@ -303,7 +315,7 @@ func (e Engine) render(tpls map[string]renderable) (rendered map[string]string,
 		vals["Template"] = chartutil.Values{"Name": filename, "BasePath": tpls[filename].basePath}
 		var buf strings.Builder
 		if err := t.ExecuteTemplate(&buf, filename, vals); err != nil {
-			return map[string]string{}, cleanupExecError(filename, err)
+			return map[string]string{}, reformatExecErrorMsg(filename, err)
 		}
 
 		// Work around the issue where Go will emit "<no value>" even if Options(missing=zero)
@@ -329,7 +341,33 @@ func cleanupParseError(filename string, err error) error {
 	return fmt.Errorf("parse error at (%s): %s", string(location), errMsg)
 }
 
-func cleanupExecError(filename string, err error) error {
+type TraceableError struct {
+	location         string
+	message          string
+	executedFunction string
+}
+
+func (t TraceableError) String() string {
+	var errorString strings.Builder
+	if t.location != "" {
+		fmt.Fprintf(&errorString, "%s\n  ", t.location)
+	}
+	if t.executedFunction != "" {
+		fmt.Fprintf(&errorString, "%s\n    ", t.executedFunction)
+	}
+	if t.message != "" {
+		fmt.Fprintf(&errorString, "%s\n", t.message)
+	}
+	return errorString.String()
+}
+
+// reformatExecErrorMsg takes an error message for template rendering and formats it into a formatted
+// multi-line error string
+func reformatExecErrorMsg(filename string, err error) error {
+	// This function matches the error message against regex's for the text/template package.
+	// If the regex's can parse out details from that error message such as the line number, template it failed on,
+	// and error description, then it will construct a new error that displays these details in a structured way.
+	// If there are issues with parsing the error message, the err passed into the function should return instead.
 	if _, isExecError := err.(template.ExecError); !isExecError {
 		return err
 	}
@@ -348,8 +386,46 @@ func cleanupExecError(filename string, err error) error {
 	if len(parts) >= 2 {
 		return fmt.Errorf("execution error at (%s): %s", string(location), parts[1])
 	}
+	current := err
+	fileLocations := []TraceableError{}
+	for current != nil {
+		var traceable TraceableError
+		if matches := execErrFmt.FindStringSubmatch(current.Error()); matches != nil {
+			templateName := matches[execErrFmt.SubexpIndex("templateName")]
+			functionName := matches[execErrFmt.SubexpIndex("functionName")]
+			locationName := matches[execErrFmt.SubexpIndex("location")]
+			errMsg := matches[execErrFmt.SubexpIndex("errMsg")]
+			traceable = TraceableError{
+				location:         templateName,
+				message:          errMsg,
+				executedFunction: "executing " + functionName + " at " + locationName + ":",
+			}
+		} else if matches := execErrFmtWithoutTemplate.FindStringSubmatch(current.Error()); matches != nil {
+			templateName := matches[execErrFmt.SubexpIndex("templateName")]
+			errMsg := matches[execErrFmt.SubexpIndex("errMsg")]
+			traceable = TraceableError{
+				location: templateName,
+				message:  errMsg,
+			}
+		} else if matches := execErrNoTemplateAssociated.FindStringSubmatch(current.Error()); matches != nil {
+			traceable = TraceableError{
+				message: current.Error(),
+			}
+		} else {
+			return err
+		}
+		if len(fileLocations) == 0 || fileLocations[len(fileLocations)-1] != traceable {
+			fileLocations = append(fileLocations, traceable)
+		}
+		current = errors.Unwrap(current)
+	}
 
-	return err
+	var finalErrorString strings.Builder
+	for _, fileLocation := range fileLocations {
+		fmt.Fprintf(&finalErrorString, "%s", fileLocation.String())
+	}
+
+	return errors.New(strings.TrimSpace(finalErrorString.String()))
 }
 
 func sortTemplates(tpls map[string]renderable) []string {

pkg/engine/engine_test.go

@@ -24,6 +24,8 @@ import (
 	"testing"
 	"text/template"
 
+	"github.com/stretchr/testify/assert"
+
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -1289,16 +1291,82 @@ func TestRenderTplMissingKeyString(t *testing.T) {
 		t.Errorf("Expected error, got %v", out)
 		return
 	}
-	switch err.(type) {
+	errTxt := fmt.Sprint(err)
-	case (template.ExecError):
+	if !strings.Contains(errTxt, "noSuchKey") {
-		errTxt := fmt.Sprint(err)
+		t.Errorf("Expected error to contain 'noSuchKey', got %s", errTxt)
-		if !strings.Contains(errTxt, "noSuchKey") {
-			t.Errorf("Expected error to contain 'noSuchKey', got %s", errTxt)
-		}
-	default:
-		// Some unexpected error.
-		t.Fatal(err)
 	}
+
+}
+
+func TestNestedHelpersProducesMultilineStacktrace(t *testing.T) {
+	c := &chart.Chart{
+		Metadata: &chart.Metadata{Name: "NestedHelperFunctions"},
+		Templates: []*chart.File{
+			{Name: "templates/svc.yaml", Data: []byte(
+				`name: {{ include "nested_helper.name" . }}`,
+			)},
+			{Name: "templates/_helpers_1.tpl", Data: []byte(
+				`{{- define "nested_helper.name" -}}{{- include "common.names.get_name" . -}}{{- end -}}`,
+			)},
+			{Name: "charts/common/templates/_helpers_2.tpl", Data: []byte(
+				`{{- define "common.names.get_name" -}}{{- .Values.nonexistant.key | trunc 63 | trimSuffix "-" -}}{{- end -}}`,
+			)},
+		},
+	}
+
+	expectedErrorMessage := `NestedHelperFunctions/templates/svc.yaml:1:9
+  executing "NestedHelperFunctions/templates/svc.yaml" at <include "nested_helper.name" .>:
+    error calling include:
+NestedHelperFunctions/templates/_helpers_1.tpl:1:39
+  executing "nested_helper.name" at <include "common.names.get_name" .>:
+    error calling include:
+NestedHelperFunctions/charts/common/templates/_helpers_2.tpl:1:49
+  executing "common.names.get_name" at <.Values.nonexistant.key>:
+    nil pointer evaluating interface {}.key`
+
+	v := chartutil.Values{}
+
+	val, _ := chartutil.CoalesceValues(c, v)
+	vals := map[string]interface{}{
+		"Values": val.AsMap(),
+	}
+	_, err := Render(c, vals)
+
+	assert.NotNil(t, err)
+	assert.Equal(t, expectedErrorMessage, err.Error())
+}
+
+func TestMultilineNoTemplateAssociatedError(t *testing.T) {
+	c := &chart.Chart{
+		Metadata: &chart.Metadata{Name: "multiline"},
+		Templates: []*chart.File{
+			{Name: "templates/svc.yaml", Data: []byte(
+				`name: {{ include "nested_helper.name" . }}`,
+			)},
+			{Name: "templates/test.yaml", Data: []byte(
+				`{{ toYaml .Values }}`,
+			)},
+			{Name: "charts/common/templates/_helpers_2.tpl", Data: []byte(
+				`{{ toYaml .Values }}`,
+			)},
+		},
+	}
+
+	expectedErrorMessage := `multiline/templates/svc.yaml:1:9
+  executing "multiline/templates/svc.yaml" at <include "nested_helper.name" .>:
+    error calling include:
+template: no template "nested_helper.name" associated with template "gotpl"`
+
+	v := chartutil.Values{}
+
+	val, _ := chartutil.CoalesceValues(c, v)
+	vals := map[string]interface{}{
+		"Values": val.AsMap(),
+	}
+	_, err := Render(c, vals)
+
+	assert.NotNil(t, err)
+	assert.Equal(t, expectedErrorMessage, err.Error())
 }
 
 func TestRenderCustomTemplateFuncs(t *testing.T) {