adds a ServiceAccount attribute to the MCPServer CRD (#1453)

Signed-off-by: ChrisJBurns <[email protected]>

Author: ChrisJBurns

cmd/thv-operator/api/v1alpha1/mcpserver_types.go

@@ -48,6 +48,11 @@ type MCPServerSpec struct {
 	// +optional
 	Secrets []SecretRef `json:"secrets,omitempty"`
 
+	// ServiceAccount is the name of an already existing service account to use by the MCP server.
+	// If not specified, a ServiceAccount will be created automatically and used by the MCP server.
+	// +optional
+	ServiceAccount *string `json:"serviceAccount,omitempty"`
+
 	// PermissionProfile defines the permission profile to use
 	// +optional
 	PermissionProfile *PermissionProfileRef `json:"permissionProfile,omitempty"`

cmd/thv-operator/api/v1alpha1/zz_generated.deepcopy.go

@@ -357,8 +357,7 @@ func (r *MCPServerReconciler) ensureRBACResources(ctx context.Context, mcpServer
 		return err
 	}
 
-	// Ensure RoleBinding
-	return r.ensureRBACResource(ctx, mcpServer, "RoleBinding", func() client.Object {
+	if err := r.ensureRBACResource(ctx, mcpServer, "RoleBinding", func() client.Object {
 		return &rbacv1.RoleBinding{
 			ObjectMeta: metav1.ObjectMeta{
 				Name:      proxyRunnerNameForRBAC,
@@ -377,6 +376,25 @@ func (r *MCPServerReconciler) ensureRBACResources(ctx context.Context, mcpServer
 				},
 			},
 		}
+	}); err != nil {
+		return err
+	}
+
+	// If a service account is specified, we don't need to create one
+	if mcpServer.Spec.ServiceAccount != nil {
+		return nil
+	}
+
+	// otherwise, create a service account for the MCP server
+	mcpServerServiceAccountName := mcpServerServiceAccountName(mcpServer.Name)
+	return r.ensureRBACResource(ctx, mcpServer, "ServiceAccount", func() client.Object {
+		mcpServer.Spec.ServiceAccount = &mcpServerServiceAccountName
+		return &corev1.ServiceAccount{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      mcpServerServiceAccountName,
+				Namespace: mcpServer.Namespace,
+			},
+		}
 	})
 }
 
@@ -399,8 +417,11 @@ func (r *MCPServerReconciler) deploymentForMCPServer(m *mcpv1alpha1.MCPServer) *
 	}
 
 	// Generate pod template patch for secrets and merge with user-provided patch
-	finalPodTemplateSpec := generateAndMergePodTemplateSpecs(m.Spec.Secrets, m.Spec.PodTemplateSpec)
 
+	finalPodTemplateSpec := NewMCPServerPodTemplateSpecBuilder(m.Spec.PodTemplateSpec).
+		WithServiceAccount(m.Spec.ServiceAccount).
+		WithSecrets(m.Spec.Secrets).
+		Build()
 	// Add pod template patch if we have one
 	if finalPodTemplateSpec != nil {
 		podTemplatePatch, err := json.Marshal(finalPodTemplateSpec)
@@ -941,7 +962,10 @@ func deploymentNeedsUpdate(deployment *appsv1.Deployment, mcpServer *mcpv1alpha1
 		}
 
 		// Check if the pod template spec has changed (including secrets)
-		expectedPodTemplateSpec := generateAndMergePodTemplateSpecs(mcpServer.Spec.Secrets, mcpServer.Spec.PodTemplateSpec)
+		expectedPodTemplateSpec := NewMCPServerPodTemplateSpecBuilder(mcpServer.Spec.PodTemplateSpec).
+			WithServiceAccount(mcpServer.Spec.ServiceAccount).
+			WithSecrets(mcpServer.Spec.Secrets).
+			Build()
 
 		// Find the current pod template patch in the container args
 		var currentPodTemplatePatch string
@@ -1089,6 +1113,11 @@ func proxyRunnerServiceAccountName(mcpServerName string) string {
 	return fmt.Sprintf("%s-proxy-runner", mcpServerName)
 }
 
+// mcpServerServiceAccountName returns the service account name for the mcp server
+func mcpServerServiceAccountName(mcpServerName string) string {
+	return fmt.Sprintf("%s-sa", mcpServerName)
+}
+
 // labelsForMCPServer returns the labels for selecting the resources
 // belonging to the given MCPServer CR name.
 func labelsForMCPServer(name string) map[string]string {
@@ -1511,103 +1540,6 @@ func int32Ptr(i int32) *int32 {
 	return &i
 }
 
-// generateSecretsPodTemplatePatch generates a podTemplateSpec patch for secrets
-func generateSecretsPodTemplatePatch(secrets []mcpv1alpha1.SecretRef) *corev1.PodTemplateSpec {
-	if len(secrets) == 0 {
-		return nil
-	}
-
-	envVars := make([]corev1.EnvVar, 0, len(secrets))
-	for _, secret := range secrets {
-		targetEnv := secret.Key
-		if secret.TargetEnvName != "" {
-			targetEnv = secret.TargetEnvName
-		}
-
-		envVars = append(envVars, corev1.EnvVar{
-			Name: targetEnv,
-			ValueFrom: &corev1.EnvVarSource{
-				SecretKeyRef: &corev1.SecretKeySelector{
-					LocalObjectReference: corev1.LocalObjectReference{
-						Name: secret.Name,
-					},
-					Key: secret.Key,
-				},
-			},
-		})
-	}
-
-	return &corev1.PodTemplateSpec{
-		Spec: corev1.PodSpec{
-			Containers: []corev1.Container{
-				{
-					Name: mcpContainerName,
-					Env:  envVars,
-				},
-			},
-		},
-	}
-}
-
-// mergePodTemplateSpecs merges a secrets patch with a user-provided podTemplateSpec
-func mergePodTemplateSpecs(secretsPatch, userPatch *corev1.PodTemplateSpec) *corev1.PodTemplateSpec {
-	// If no secrets, return user patch as-is
-	if secretsPatch == nil {
-		return userPatch
-	}
-
-	// If no user patch, return secrets patch
-	if userPatch == nil {
-		return secretsPatch
-	}
-
-	// Start with user patch as base (preserves all user customizations)
-	result := userPatch.DeepCopy()
-
-	// Find or create mcp container in result
-	mcpIndex := -1
-	for i, container := range result.Spec.Containers {
-		if container.Name == mcpContainerName {
-			mcpIndex = i
-			break
-		}
-	}
-
-	// Get secret env vars from secrets patch
-	var secretEnvVars []corev1.EnvVar
-	for _, container := range secretsPatch.Spec.Containers {
-		if container.Name == mcpContainerName {
-			secretEnvVars = container.Env
-			break
-		}
-	}
-
-	if mcpIndex >= 0 {
-		// Merge env vars into existing mcp container
-		result.Spec.Containers[mcpIndex].Env = append(
-			result.Spec.Containers[mcpIndex].Env,
-			secretEnvVars...,
-		)
-	} else {
-		// Add new mcp container with just env vars
-		result.Spec.Containers = append(result.Spec.Containers, corev1.Container{
-			Name: mcpContainerName,
-			Env:  secretEnvVars,
-		})
-	}
-
-	return result
-}
-
-// generateAndMergePodTemplateSpecs generates secrets patch and merges with user patch
-func generateAndMergePodTemplateSpecs(
-	secrets []mcpv1alpha1.SecretRef,
-	userPatch *corev1.PodTemplateSpec,
-) *corev1.PodTemplateSpec {
-	secretsPatch := generateSecretsPodTemplatePatch(secrets)
-	return mergePodTemplateSpecs(secretsPatch, userPatch)
-}
-
 // SetupWithManager sets up the controller with the Manager.
 func (r *MCPServerReconciler) SetupWithManager(mgr ctrl.Manager) error {
 	return ctrl.NewControllerManagedBy(mgr).

cmd/thv-operator/controllers/mcpserver_controller.go

@@ -0,0 +1,107 @@
+package controllers
+
+import (
+	corev1 "k8s.io/api/core/v1"
+
+	mcpv1alpha1 "github.com/stacklok/toolhive/cmd/thv-operator/api/v1alpha1"
+)
+
+// MCPServerPodTemplateSpecBuilder provides an interface for building PodTemplateSpec patches for MCP Servers
+type MCPServerPodTemplateSpecBuilder struct {
+	spec *corev1.PodTemplateSpec
+}
+
+// NewMCPServerPodTemplateSpecBuilder creates a new builder, optionally starting with a user-provided template
+func NewMCPServerPodTemplateSpecBuilder(userTemplate *corev1.PodTemplateSpec) *MCPServerPodTemplateSpecBuilder {
+	var spec *corev1.PodTemplateSpec
+	if userTemplate != nil {
+		spec = userTemplate.DeepCopy()
+	} else {
+		spec = &corev1.PodTemplateSpec{
+			Spec: corev1.PodSpec{
+				Containers: []corev1.Container{},
+			},
+		}
+	}
+
+	return &MCPServerPodTemplateSpecBuilder{spec: spec}
+}
+
+// WithServiceAccount sets the service account name
+func (b *MCPServerPodTemplateSpecBuilder) WithServiceAccount(serviceAccount *string) *MCPServerPodTemplateSpecBuilder {
+	if serviceAccount != nil && *serviceAccount != "" {
+		b.spec.Spec.ServiceAccountName = *serviceAccount
+	}
+	return b
+}
+
+// WithSecrets adds secret environment variables to the MCP container
+func (b *MCPServerPodTemplateSpecBuilder) WithSecrets(secrets []mcpv1alpha1.SecretRef) *MCPServerPodTemplateSpecBuilder {
+	if len(secrets) == 0 {
+		return b
+	}
+
+	// Generate secret env vars
+	secretEnvVars := make([]corev1.EnvVar, 0, len(secrets))
+	for _, secret := range secrets {
+		targetEnv := secret.Key
+		if secret.TargetEnvName != "" {
+			targetEnv = secret.TargetEnvName
+		}
+
+		secretEnvVars = append(secretEnvVars, corev1.EnvVar{
+			Name: targetEnv,
+			ValueFrom: &corev1.EnvVarSource{
+				SecretKeyRef: &corev1.SecretKeySelector{
+					LocalObjectReference: corev1.LocalObjectReference{
+						Name: secret.Name,
+					},
+					Key: secret.Key,
+				},
+			},
+		})
+	}
+
+	if len(secretEnvVars) == 0 {
+		return b
+	}
+
+	// add secret env vars to MCP container
+	mcpIndex := -1
+	for i, container := range b.spec.Spec.Containers {
+		if container.Name == mcpContainerName {
+			mcpIndex = i
+			break
+		}
+	}
+
+	if mcpIndex >= 0 {
+		// Merge env vars into existing MCP container
+		b.spec.Spec.Containers[mcpIndex].Env = append(
+			b.spec.Spec.Containers[mcpIndex].Env,
+			secretEnvVars...,
+		)
+	} else {
+		// Add new MCP container with env vars
+		b.spec.Spec.Containers = append(b.spec.Spec.Containers, corev1.Container{
+			Name: mcpContainerName,
+			Env:  secretEnvVars,
+		})
+	}
+	return b
+}
+
+// Build returns the final PodTemplateSpec, or nil if no customizations were made
+func (b *MCPServerPodTemplateSpecBuilder) Build() *corev1.PodTemplateSpec {
+	// Return nil if the spec is effectively empty (no meaningful customizations)
+	if b.isEmpty() {
+		return nil
+	}
+	return b.spec
+}
+
+// isEmpty checks if the builder contains any meaningful customizations
+func (b *MCPServerPodTemplateSpecBuilder) isEmpty() bool {
+	return b.spec.Spec.ServiceAccountName == "" &&
+		len(b.spec.Spec.Containers) == 0
+}