From 422b18c2a749a51b0d32ad87a0b93d5a9f7e8380 Mon Sep 17 00:00:00 2001
From: Yash Mehrotra <yashmehrotra95@gmail.com>
Date: Wed, 31 May 2023 14:05:40 +0530
Subject: [PATCH] feat: add generic reconciler

---
 manager.go    | 32 +++---------------
 reconciler.go | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 98 insertions(+), 27 deletions(-)
 create mode 100644 reconciler.go

diff --git a/manager.go b/manager.go
index 72bdaec..e71aaf7 100644
--- a/manager.go
+++ b/manager.go
@@ -12,11 +12,6 @@ import (
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
-
-	"github.com/flanksource/commons/collections"
-	missioncontrolv1 "github.com/flanksource/kopper/api/v1"
-	"github.com/flanksource/kopper/controllers"
-	//+kubebuilder:scaffold:imports
 )
 
 var (
@@ -25,22 +20,20 @@ var (
 
 func init() {
 	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
-
-	utilruntime.Must(missioncontrolv1.AddToScheme(scheme))
 }
 
 type ManagerOptions struct {
-	MetricsBindAddress     string
-	LeaderElectionID       string
-	Reconcilers            []string
-	ConnectionOnUpsertFunc func(missioncontrolv1.Connection) error
-	ConnectionOnDeleteFunc func(string) error
+	MetricsBindAddress string
+	LeaderElectionID   string
+	AddToSchemeFunc    func(*runtime.Scheme) error
 }
 
 func Manager(opts *ManagerOptions) (manager.Manager, error) {
 	if opts == nil {
 		opts = &ManagerOptions{}
 	}
+
+	utilruntime.Must(opts.AddToSchemeFunc(scheme))
 	// Use options for reconciling setup
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme:             scheme,
@@ -64,20 +57,5 @@ func Manager(opts *ManagerOptions) (manager.Manager, error) {
 		return nil, fmt.Errorf("error setting up manager: %w", err)
 	}
 
-	if len(opts.Reconcilers) == 0 {
-		return nil, fmt.Errorf("no reconcilers given")
-	}
-
-	if collections.Contains(opts.Reconcilers, "Connection") {
-		if err = (&controllers.ConnectionReconciler{
-			Client:       mgr.GetClient(),
-			Scheme:       mgr.GetScheme(),
-			OnUpsertFunc: opts.ConnectionOnUpsertFunc,
-			OnDeleteFunc: opts.ConnectionOnDeleteFunc,
-		}).SetupWithManager(mgr); err != nil {
-			return nil, fmt.Errorf("unable to create controller for Connection: %v", err)
-		}
-	}
-
 	return mgr, nil
 }
diff --git a/reconciler.go b/reconciler.go
new file mode 100644
index 0000000..4399581
--- /dev/null
+++ b/reconciler.go
@@ -0,0 +1,93 @@
+package kopper
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/flanksource/commons/logger"
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/runtime"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
+)
+
+func SetupReconciler[T any, PT interface {
+	*T
+	client.Object
+}](mgr ctrl.Manager, OnUpsertFunc func(PT) error, OnDeleteFunc func(string) error, finalizer string) error {
+	if finalizer == "" {
+		return fmt.Errorf("field Finalizer cannot be empty")
+	}
+
+	r := Reconciler[T, PT]{
+		Client:       mgr.GetClient(),
+		Scheme:       mgr.GetScheme(),
+		OnUpsertFunc: OnUpsertFunc,
+		OnDeleteFunc: OnDeleteFunc,
+		Finalizer:    finalizer,
+	}
+
+	return r.SetupWithManager(mgr)
+}
+
+type Reconciler[T any, PT interface {
+	*T
+	client.Object
+}] struct {
+	client.Client
+	Scheme       *runtime.Scheme
+	OnUpsertFunc func(PT) error
+	OnDeleteFunc func(string) error
+	Finalizer    string
+}
+
+func (r *Reconciler[T, PT]) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+	obj := PT(new(T))
+
+	err := r.Get(ctx, req.NamespacedName, obj)
+	if err != nil {
+		if errors.IsNotFound(err) {
+			return ctrl.Result{}, nil
+		}
+		return ctrl.Result{}, err
+	}
+
+	resourceName := fmt.Sprintf("%s[%s]", obj.GetObjectKind().GroupVersionKind().Kind, obj.GetUID())
+
+	if !obj.GetDeletionTimestamp().IsZero() {
+		logger.Infof("[kopper] deleting %s", resourceName)
+		if err := r.OnDeleteFunc(string(obj.GetUID())); err != nil {
+			logger.Errorf("[kopper] failed to delete %s: %v", resourceName, err)
+			return ctrl.Result{Requeue: true, RequeueAfter: 2 * time.Minute}, err
+		}
+		controllerutil.RemoveFinalizer(obj, r.Finalizer)
+		return ctrl.Result{}, r.Update(ctx, obj)
+	}
+
+	if !controllerutil.ContainsFinalizer(obj, r.Finalizer) {
+		controllerutil.AddFinalizer(obj, r.Finalizer)
+		if err := r.Update(ctx, obj); err != nil {
+			logger.Errorf("[kopper] failed to update finalizers %s: %v", resourceName, err)
+			return ctrl.Result{Requeue: true, RequeueAfter: 2 * time.Minute}, err
+		}
+	}
+
+	if err := r.OnUpsertFunc(obj); err != nil {
+		logger.Errorf("[kopper] failed to upsert %s: %v", resourceName, err)
+		return ctrl.Result{Requeue: true, RequeueAfter: 2 * time.Minute}, err
+	}
+
+	logger.Infof("[kopper] upserted %s", resourceName)
+	return ctrl.Result{}, nil
+
+}
+
+// SetupWithManager sets up the controller with the Manager.
+func (r *Reconciler[T, PT]) SetupWithManager(mgr ctrl.Manager) error {
+	pObj := PT(new(T))
+	return ctrl.NewControllerManagedBy(mgr).
+		For(pObj).
+		Complete(r)
+}