From e77ba0f9531433ceb27955898c4ca9a799943965 Mon Sep 17 00:00:00 2001
From: Viacheslav Sarzhan <slava.sarzhan@percona.com>
Date: Fri, 12 Sep 2025 20:29:22 +0300
Subject: [PATCH] K8SPSMDB-1466 improve MCS error handling to prevent operator
 crashes

---
 pkg/mcs/register.go      |  6 ++--
 pkg/mcs/register_test.go | 60 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 pkg/mcs/register_test.go

diff --git a/pkg/mcs/register.go b/pkg/mcs/register.go
index 402ae7886b..0137298b43 100644
--- a/pkg/mcs/register.go
+++ b/pkg/mcs/register.go
@@ -1,7 +1,6 @@
 package mcs
 
 import (
-	"github.com/pkg/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -36,7 +35,10 @@ func addKnownTypes(scheme *runtime.Scheme) error {
 func Register(dc *discovery.DiscoveryClient) error {
 	resources, err := dc.ServerPreferredResources()
 	if err != nil {
-		return errors.Wrap(err, "get api groups and resources")
+		// MCS is optional functionality - if discovery fails for any reason,
+		// mark it as unavailable and continue without crashing the operator
+		available = false
+		return nil
 	}
 
 outer:
diff --git a/pkg/mcs/register_test.go b/pkg/mcs/register_test.go
new file mode 100644
index 0000000000..3628d84f40
--- /dev/null
+++ b/pkg/mcs/register_test.go
@@ -0,0 +1,60 @@
+package mcs
+
+import (
+	"testing"
+)
+
+func TestIsAvailable(t *testing.T) {
+	// Test IsAvailable function
+	available = true
+	if !IsAvailable() {
+		t.Error("Expected IsAvailable to return true when available is true")
+	}
+
+	available = false
+	if IsAvailable() {
+		t.Error("Expected IsAvailable to return false when available is false")
+	}
+}
+
+func TestMCSSchemeGroupVersion(t *testing.T) {
+	// Test that MCSSchemeGroupVersion is initialized correctly
+	if MCSSchemeGroupVersion.Group != "" {
+		t.Errorf("Expected MCSSchemeGroupVersion.Group to be empty initially, got: %s", MCSSchemeGroupVersion.Group)
+	}
+	if MCSSchemeGroupVersion.Version != "" {
+		t.Errorf("Expected MCSSchemeGroupVersion.Version to be empty initially, got: %s", MCSSchemeGroupVersion.Version)
+	}
+}
+
+func TestServiceExport(t *testing.T) {
+	// Test ServiceExport creation
+	namespace := "test-namespace"
+	name := "test-service"
+	labels := map[string]string{
+		"app": "test",
+	}
+
+	se := ServiceExport(namespace, name, labels)
+
+	if se.Name != name {
+		t.Errorf("Expected ServiceExport name to be %s, got: %s", name, se.Name)
+	}
+
+	if se.Namespace != namespace {
+		t.Errorf("Expected ServiceExport namespace to be %s, got: %s", namespace, se.Namespace)
+	}
+
+	if se.Labels["app"] != "test" {
+		t.Errorf("Expected ServiceExport label 'app' to be 'test', got: %s", se.Labels["app"])
+	}
+}
+
+func TestServiceExportList(t *testing.T) {
+	// Test ServiceExportList creation
+	seList := ServiceExportList()
+
+	if seList.Kind != "ServiceExportList" {
+		t.Errorf("Expected ServiceExportList Kind to be 'ServiceExportList', got: %s", seList.Kind)
+	}
+}