Fix HasHighlyAvailableControlPlane to use AllInstanceGroups

When using 'kops update cluster' with --instance-group or
--instance-group-roles filters, the HasHighlyAvailableControlPlane
function was incorrectly using the filtered InstanceGroups list
instead of AllInstanceGroups.

This caused cluster-wide controllers like aws-load-balancer-controller
and node-termination-handler to incorrectly downscale replicas from 2
to 1 when updating a specific instance group in an HA cluster.

The fix changes HasHighlyAvailableControlPlane to use AllInstanceGroups
since HA status is a cluster-wide property, not specific to filtered
instance groups.

Fixes #17739

Signed-off-by: Peter Kubicsek <[email protected]>

Author: pkubicsek-sb

upup/pkg/fi/cloudup/template_functions.go

@@ -499,7 +499,7 @@ func (tf *TemplateFunctions) APIServerNodeRole() string {
 // HasHighlyAvailableControlPlane returns true of the cluster has more than one control plane node. False otherwise.
 func (tf *TemplateFunctions) HasHighlyAvailableControlPlane() bool {
 	cp := 0
-	for _, ig := range tf.InstanceGroups {
+	for _, ig := range tf.AllInstanceGroups {
 		if ig.Spec.Role == kops.InstanceGroupRoleControlPlane {
 			cp++
 			if cp > 1 {

upup/pkg/fi/cloudup/template_functions_test.go

@@ -21,6 +21,7 @@ import (
 	"reflect"
 	"testing"
 
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/pkg/featureflag"
 	"k8s.io/kops/upup/pkg/fi"
@@ -313,3 +314,130 @@ func TestKopsFeatureEnabled(t *testing.T) {
 		})
 	}
 }
+
+func TestHasHighlyAvailableControlPlane(t *testing.T) {
+	tests := []struct {
+		name              string
+		allInstanceGroups []*kops.InstanceGroup
+		instanceGroups    []*kops.InstanceGroup
+		expectedHA        bool
+	}{
+		{
+			name: "Single control plane node",
+			allInstanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1a"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			instanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			expectedHA: false,
+		},
+		{
+			name: "Multiple control plane nodes",
+			allInstanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1a"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1b"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			instanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			expectedHA: true,
+		},
+		{
+			name: "Multiple control plane nodes with filtered instance groups (regression test)",
+			allInstanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1a"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1b"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1c"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			instanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "nodes"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleNode},
+				},
+			},
+			expectedHA: true,
+		},
+		{
+			name: "Three control plane nodes",
+			allInstanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1a"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1b"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1c"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+			},
+			instanceGroups: []*kops.InstanceGroup{
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1a"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1b"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{Name: "master-us-east-1c"},
+					Spec:       kops.InstanceGroupSpec{Role: kops.InstanceGroupRoleControlPlane},
+				},
+			},
+			expectedHA: true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			tf := &TemplateFunctions{}
+			tf.AllInstanceGroups = tc.allInstanceGroups
+			tf.InstanceGroups = tc.instanceGroups
+
+			actual := tf.HasHighlyAvailableControlPlane()
+			if actual != tc.expectedHA {
+				t.Errorf("expected HA to be %t, got %t", tc.expectedHA, actual)
+			}
+		})
+	}
+}