From 1e8b02e4f64018685957082aa9c5c1b59c4e9260 Mon Sep 17 00:00:00 2001
From: bmurray <bmurray@newrelic.com>
Date: Mon, 18 Mar 2024 13:10:02 -0700
Subject: [PATCH] adding logic to remove old instance templates as they're no
 longer needed.

---
 .../services/compute/instancegroups/client.go |  6 +++
 .../compute/instancegroups/instancegroups.go  | 47 +++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/cloud/services/compute/instancegroups/client.go b/cloud/services/compute/instancegroups/client.go
index 041dd3972..704f089d1 100644
--- a/cloud/services/compute/instancegroups/client.go
+++ b/cloud/services/compute/instancegroups/client.go
@@ -37,6 +37,7 @@ type Client interface {
 	ListInstanceGroupInstances(ctx context.Context, project, zone, name string) (*compute.InstanceGroupManagersListManagedInstancesResponse, error)
 	// InstanceGroupTemplate Interfaces
 	GetInstanceTemplate(ctx context.Context, project, name string) (*compute.InstanceTemplate, error)
+	ListInstanceTemplates(ctx context.Context, project string) (*compute.InstanceTemplateList, error)
 	CreateInstanceTemplate(ctx context.Context, project string, instanceTemplate *compute.InstanceTemplate) (*compute.Operation, error)
 	DeleteInstanceTemplate(ctx context.Context, project, name string) (*compute.Operation, error)
 	WaitUntilOperationCompleted(project, operation string) error
@@ -98,6 +99,11 @@ func (c *GCPClient) GetInstanceTemplate(_ context.Context, project, name string)
 	return c.service.InstanceTemplates.Get(project, name).Do()
 }
 
+// ListInstanceTemplates returns a list of instance templates in a project.
+func (c *GCPClient) ListInstanceTemplates(_ context.Context, project string) (*compute.InstanceTemplateList, error) {
+	return c.service.InstanceTemplates.List(project).Do()
+}
+
 // CreateInstanceTemplate creates a new instance template in a project.
 func (c *GCPClient) CreateInstanceTemplate(_ context.Context, project string, instanceTemplate *compute.InstanceTemplate) (*compute.Operation, error) {
 	return c.service.InstanceTemplates.Insert(project, instanceTemplate).Do()
diff --git a/cloud/services/compute/instancegroups/instancegroups.go b/cloud/services/compute/instancegroups/instancegroups.go
index c1622cd86..d6fb0e005 100644
--- a/cloud/services/compute/instancegroups/instancegroups.go
+++ b/cloud/services/compute/instancegroups/instancegroups.go
@@ -115,6 +115,11 @@ func (s *Service) Reconcile(ctx context.Context) (ctrl.Result, error) {
 			log.Error(err, "Error updating instance group")
 			return ctrl.Result{}, err
 		}
+		err = s.removeOldInstanceTemplate(ctx, instanceTemplateName)
+		if err != nil {
+			log.Error(err, "Error removing old instance templates")
+			return ctrl.Result{}, err
+		}
 	}
 
 	// Re-get the instance group after updating it. This is needed to get the latest status.
@@ -234,6 +239,48 @@ func (s *Service) patchInstanceGroup(ctx context.Context, instanceTemplateName s
 	return nil
 }
 
+// removeOldInstanceTemplate removes the old instance templates.
+func (s *Service) removeOldInstanceTemplate(ctx context.Context, instanceTemplateName string) error {
+	log := log.FromContext(ctx)
+	log.Info("Starting to remove old instance templates", "templateName", instanceTemplateName)
+
+	// List all instance templates.
+	instanceTemplates, err := s.Client.ListInstanceTemplates(ctx, s.scope.Project())
+	if err != nil {
+		log.Error(err, "Error listing instance templates")
+		return err
+	}
+
+	// Prepare to identify instance templates to remove.
+	lastIndex := strings.LastIndex(instanceTemplateName, "-")
+	if lastIndex == -1 {
+		log.Error(fmt.Errorf("invalid instance template name format"), "Invalid template name", "templateName", instanceTemplateName)
+		return fmt.Errorf("invalid instance template name format: %s", instanceTemplateName)
+	}
+
+	trimmedInstanceTemplateName := instanceTemplateName[:lastIndex]
+	var errors []error
+
+	for _, instanceTemplate := range instanceTemplates.Items {
+		if strings.HasPrefix(instanceTemplate.Name, trimmedInstanceTemplateName) && instanceTemplate.Name != instanceTemplateName {
+			log.Info("Deleting instance template", "templateName", instanceTemplate.Name)
+			_, err := s.Client.DeleteInstanceTemplate(ctx, s.scope.Project(), instanceTemplate.Name)
+			if err != nil {
+				log.Error(err, "Error deleting instance template", "templateName", instanceTemplate.Name)
+				errors = append(errors, err)
+				continue // Proceed to next template instead of returning immediately.
+			}
+		}
+	}
+
+	// Aggregate errors (if any).
+	if len(errors) > 0 {
+		return fmt.Errorf("encountered errors during deletion: %v", errors)
+	}
+
+	return nil
+}
+
 // Delete deletes the instance group.
 func (s *Service) Delete(ctx context.Context) (ctrl.Result, error) {
 	log := log.FromContext(ctx)