feat: Allow helm templater plugin to get custom prefixes from kustomize

Author: liam-mackie

pkg/plugins/optional/helm/v2alpha/scaffolds/edit_kustomize.go

@@ -109,6 +109,7 @@ func (s *editKustomizeScaffolder) Scaffold() error {
 			slog.Warn("failed to remove stale generic ServiceMonitor", "path", staleSM, "error", rmErr)
 		}
 	}
+	namePrefix := resources.EstimatePrefix(s.config.GetProjectName())
 	chartConverter := kustomize.NewChartConverter(resources, s.config.GetProjectName(), s.outputDir)
 	deploymentConfig := chartConverter.ExtractDeploymentConfig()
 
@@ -119,7 +120,8 @@ func (s *editKustomizeScaffolder) Scaffold() error {
 	chartFiles := []machinery.Builder{
 		&github.HelmChartCI{},                        // GitHub Actions workflow for chart testing
 		&templates.HelmChart{OutputDir: s.outputDir}, // Chart.yaml metadata
-		&templates.HelmValuesBasic{ // values.yaml with dynamic config
+		&templates.HelmValuesBasic{
+			// values.yaml with dynamic config
 			HasWebhooks:      hasWebhooks,
 			HasMetrics:       hasMetrics,
 			DeploymentConfig: deploymentConfig,
@@ -134,7 +136,20 @@ func (s *editKustomizeScaffolder) Scaffold() error {
 	// provide one via kustomize (../prometheus). This avoids duplicate objects
 	// with the same name within the Helm chart.
 	if !hasPrometheus {
-		chartFiles = append(chartFiles, &charttemplates.ServiceMonitor{OutputDir: s.outputDir})
+		// Find the metrics service name from parsed resources
+		metricsServiceName := namePrefix + "-controller-manager-metrics-service"
+		for _, svc := range resources.Services {
+			if strings.Contains(svc.GetName(), "metrics-service") {
+				metricsServiceName = svc.GetName()
+				break
+			}
+		}
+
+		chartFiles = append(chartFiles, &charttemplates.ServiceMonitor{
+			OutputDir:   s.outputDir,
+			NamePrefix:  namePrefix,
+			ServiceName: metricsServiceName,
+		})
 	}
 
 	// Generate template files from kustomize output

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/kustomize/chart_writer.go

@@ -44,7 +44,8 @@ func NewChartWriter(templater *HelmTemplater, outputDir string) *ChartWriter {
 }
 
 // WriteResourceGroup writes a group of resources to a Helm template file
-func (w *ChartWriter) WriteResourceGroup(fs machinery.Filesystem, groupName string,
+func (w *ChartWriter) WriteResourceGroup(
+	fs machinery.Filesystem, groupName string,
 	resources []*unstructured.Unstructured,
 ) error {
 	// Special handling for namespace - write as single file
@@ -73,7 +74,8 @@ func (w *ChartWriter) writeNamespaceFile(fs machinery.Filesystem, namespace *uns
 }
 
 // writeGroupDirectory writes resources as files in a group-specific directory
-func (w *ChartWriter) writeGroupDirectory(fs machinery.Filesystem, groupName string,
+func (w *ChartWriter) writeGroupDirectory(
+	fs machinery.Filesystem, groupName string,
 	resources []*unstructured.Unstructured,
 ) error {
 	var finalContent bytes.Buffer
@@ -112,7 +114,8 @@ func (w *ChartWriter) shouldSplitFiles(groupName string) bool {
 }
 
 // writeSplitFiles writes each resource in the group to its own file
-func (w *ChartWriter) writeSplitFiles(fs machinery.Filesystem, groupName string,
+func (w *ChartWriter) writeSplitFiles(
+	fs machinery.Filesystem, groupName string,
 	resources []*unstructured.Unstructured,
 ) error {
 	// Create the group directory

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/kustomize/helm_templater.go

@@ -68,9 +68,6 @@ func (t *HelmTemplater) ApplyHelmSubstitutions(yamlContent string, resource *uns
 	// Apply namespace substitutions
 	yamlContent = t.substituteNamespace(yamlContent, resource)
 
-	// Template ServiceMonitor metadata.name to be chart.name-scoped for consistency
-	yamlContent = t.templateServiceMonitorNames(yamlContent, resource)
-
 	// Apply cert-manager and webhook-specific templating AFTER other substitutions
 	yamlContent = t.substituteCertManagerReferences(yamlContent, resource)
 
@@ -159,47 +156,6 @@ func (t *HelmTemplater) substituteCertManagerReferences(yamlContent string, _ *u
 	return yamlContent
 }
 
-// templateServiceNames ensures Service metadata.name uses Helm helpers for release-scoped naming.
-// It converts hardcoded names like "<project>-webhook-service" or
-// "<project>-controller-manager-metrics-service" to:
-//
-//	name: {{ include "chart.serviceName" (dict "suffix" "<suffix>" "context" .) }}
-// NOTE: Service names are intentionally left as project-scoped (no release prefix)
-// to match existing samples and e2e tests that refer to fixed service names.
-
-// templateServiceMonitorNames ensures ServiceMonitor metadata.name uses chart.name-based naming for consistency
-// with existing tests and samples. It converts names like "controller-manager-metrics-monitor" or
-// "<project>-controller-manager-metrics-monitor" to:
-//
-//	name: {{ include "chart.name" . }}-controller-manager-metrics-monitor
-func (t *HelmTemplater) templateServiceMonitorNames(yamlContent string, resource *unstructured.Unstructured) string {
-	if resource.GetKind() != kindServiceMonitor {
-		return yamlContent
-	}
-
-	origName := resource.GetName()
-	if origName == "" {
-		return yamlContent
-	}
-
-	// Normalize suffix by stripping the project prefix if present
-	suffix := origName
-	prefix := t.projectName + "-"
-	if strings.HasPrefix(origName, prefix) {
-		suffix = strings.TrimPrefix(origName, prefix)
-	}
-
-	// Only template if the intended target follows the conventional suffix
-	// This keeps any custom user-provided names intact
-	// For default scaffolding, suffix is typically "controller-manager-metrics-monitor"
-	templated := "{{ include \"chart.name\" . }}-" + suffix
-
-	nameRe := regexp.MustCompile("(?m)^([\t ]*)name:\\s*" + regexp.QuoteMeta(origName) + "\\s*$")
-	yamlContent = nameRe.ReplaceAllString(yamlContent, "${1}name: "+templated)
-
-	return yamlContent
-}
-
 // addHelmLabelsAndAnnotations replaces kustomize managed-by labels with Helm equivalents
 func (t *HelmTemplater) addHelmLabelsAndAnnotations(yamlContent string, _ *unstructured.Unstructured) string {
 	// Replace app.kubernetes.io/managed-by: kustomize with Helm template

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/kustomize/helm_templater_test.go

@@ -389,6 +389,23 @@ metadata:
 			Expect(result).To(ContainSubstring("name: test-project-controller-manager"))
 			Expect(result).NotTo(ContainSubstring("{{ include"))
 		})
+		It("should preserve name for ServiceMonitor", func() {
+			serviceMonitorResource := &unstructured.Unstructured{}
+			serviceMonitorResource.SetAPIVersion("monitoring.coreos.com/v1")
+			serviceMonitorResource.SetKind("ServiceMonitor")
+			serviceMonitorResource.SetName("test-project-controller-manager-metrics-monitor")
+
+			content := `apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: test-project-controller-manager-metrics-monitor`
+
+			result := templater.ApplyHelmSubstitutions(content, serviceMonitorResource)
+
+			// Name should remain unchanged
+			Expect(result).To(ContainSubstring("name: test-project-controller-manager-metrics-monitor"))
+			Expect(result).NotTo(ContainSubstring("{{ include"))
+		})
 	})
 
 	Context("edge cases", func() {

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/kustomize/parser.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strings"
 
 	"gopkg.in/yaml.v3"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -151,3 +152,26 @@ func (p *Parser) categorizeResource(obj *unstructured.Unstructured, resources *P
 		resources.Other = append(resources.Other, obj)
 	}
 }
+
+func (pr *ParsedResources) EstimatePrefix(projectName string) string {
+	prefix := projectName
+	if pr.Deployment != nil {
+		if name := pr.Deployment.GetName(); name != "" {
+			deploymentPrefix, found := strings.CutSuffix(name, "-controller-manager")
+			if found {
+				prefix = deploymentPrefix
+			}
+		}
+	}
+	// Double check that the prefix is also the prefix for the service names
+	for _, svc := range pr.Services {
+		if name := svc.GetName(); name != "" {
+			if !strings.HasPrefix(name, prefix) {
+				// If not, fallback to just project name
+				prefix = projectName
+				break
+			}
+		}
+	}
+	return prefix
+}

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/kustomize/parser_test.go

@@ -283,4 +283,42 @@ spec:
 			Expect(issuer.GetKind()).To(Equal("Issuer"))
 		})
 	})
+
+	Context("with custom prefix", func() {
+		BeforeEach(func() {
+			yamlContent := `---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: ln-controller-manager
+  namespace: long-name-test-system
+spec:
+  replicas: 1
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: ln-controller-manager-metrics-service
+  namespace: long-name-test-system
+spec:
+  ports:
+  - name: https
+    port: 8443
+    targetPort: 8443
+  selector:
+    control-plane: ln-controller-manager
+`
+			err := os.WriteFile(tempFile, []byte(yamlContent), 0o600)
+			Expect(err).NotTo(HaveOccurred())
+
+			parser = NewParser(tempFile)
+		})
+
+		It("should use the correct prefix", func() {
+			resources, err := parser.Parse()
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(resources.EstimatePrefix("long-name")).To(Equal("ln"))
+		})
+	})
 })

pkg/plugins/optional/helm/v2alpha/scaffolds/internal/templates/chart-templates/servicemonitor.go

@@ -29,7 +29,12 @@ var _ machinery.Template = &ServiceMonitor{}
 // ServiceMonitor scaffolds a ServiceMonitor for Prometheus monitoring in the Helm chart
 type ServiceMonitor struct {
 	machinery.TemplateMixin
-	machinery.ProjectNameMixin
+
+	// Prefix
+	NamePrefix string
+
+	// ServiceName is the full name of the metrics service, derived from Kustomize
+	ServiceName string
 
 	// OutputDir specifies the output directory for the chart
 	OutputDir string
@@ -59,7 +64,7 @@ metadata:
   labels:
     {{ "{{- include \"chart.labels\" . | nindent 4 }}" }}
     control-plane: controller-manager
-  name: {{ .ProjectName }}-controller-manager-metrics-monitor
+  name: {{ .NamePrefix }}-controller-manager-metrics-monitor
   namespace: {{ "{{ .Release.Namespace }}" }}
 spec:
   endpoints:
@@ -69,7 +74,7 @@ spec:
       bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
       tlsConfig:
         {{ "{{- if .Values.certManager.enable }}" }}
-        serverName: {{ .ProjectName }}-controller-manager-metrics-service.{{ "{{ .Release.Namespace }}" }}.svc
+        serverName: {{ .ServiceName }}.{{ "{{ .Release.Namespace }}" }}.svc
         # Apply secure TLS configuration with cert-manager
         insecureSkipVerify: false
         ca: