From d341a5b9d31c6d2a61d1cbcf68b9736054534197 Mon Sep 17 00:00:00 2001
From: Fabio Kung <fkung@netflix.com>
Date: Wed, 22 Apr 2020 12:02:40 -0700
Subject: [PATCH] kube-scheduler: compatibility with ServerSideApply

avoid moving Pods that have been assumed back to the scheduling queue in
case they have annotations modified with ServerSideApply, which causes
Pod.ObjectMeta.ManagedFields to be modified automatically
---
 pkg/scheduler/eventhandlers.go      |  3 ++
 pkg/scheduler/eventhandlers_test.go | 79 +++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/pkg/scheduler/eventhandlers.go b/pkg/scheduler/eventhandlers.go
index f6d8bb1c96a..0b4f6d99011 100644
--- a/pkg/scheduler/eventhandlers.go
+++ b/pkg/scheduler/eventhandlers.go
@@ -335,6 +335,9 @@ func (sched *Scheduler) skipPodUpdate(pod *v1.Pod) bool {
 		// Annotations must be excluded for the reasons described in
 		// https://github.com/kubernetes/kubernetes/issues/52914.
 		p.Annotations = nil
+		// Same as above, when annotations are modified with ServerSideApply,
+		// ManagedFields may also change and must be excluded
+		p.ManagedFields = nil
 		return p
 	}
 	assumedPodCopy, podCopy := f(assumedPod), f(pod)
diff --git a/pkg/scheduler/eventhandlers_test.go b/pkg/scheduler/eventhandlers_test.go
index 1d267ba8ffc..406f7d7089b 100644
--- a/pkg/scheduler/eventhandlers_test.go
+++ b/pkg/scheduler/eventhandlers_test.go
@@ -80,6 +80,85 @@ func TestSkipPodUpdate(t *testing.T) {
 			},
 			expected: true,
 		},
+		{
+			name: "with ServerSideApply changes on Annotations",
+			pod: &v1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "pod-0",
+					Annotations:     map[string]string{"a": "b"},
+					ResourceVersion: "0",
+					ManagedFields: []metav1.ManagedFieldsEntry{
+						{
+							Manager:    "some-actor",
+							Operation:  metav1.ManagedFieldsOperationApply,
+							APIVersion: "v1",
+							FieldsType: "FieldsV1",
+							FieldsV1: &metav1.FieldsV1{
+								Raw: []byte(`
+									"f:metadata": {
+									  "f:annotations": {
+										"f:a: {}
+									  }
+									}
+								`),
+							},
+						},
+					},
+				},
+				Spec: v1.PodSpec{
+					NodeName: "node-0",
+				},
+			},
+			isAssumedPodFunc: func(*v1.Pod) bool {
+				return true
+			},
+			getPodFunc: func(*v1.Pod) *v1.Pod {
+				return &v1.Pod{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:            "pod-0",
+						Annotations:     map[string]string{"a": "c", "d": "e"},
+						ResourceVersion: "1",
+						ManagedFields: []metav1.ManagedFieldsEntry{
+							{
+								Manager:    "some-actor",
+								Operation:  metav1.ManagedFieldsOperationApply,
+								APIVersion: "v1",
+								FieldsType: "FieldsV1",
+								FieldsV1: &metav1.FieldsV1{
+									Raw: []byte(`
+										"f:metadata": {
+										  "f:annotations": {
+											"f:a: {}
+											"f:d: {}
+										  }
+										}
+									`),
+								},
+							},
+							{
+								Manager:    "some-actor",
+								Operation:  metav1.ManagedFieldsOperationApply,
+								APIVersion: "v1",
+								FieldsType: "FieldsV1",
+								FieldsV1: &metav1.FieldsV1{
+									Raw: []byte(`
+										"f:metadata": {
+										  "f:annotations": {
+											"f:a: {}
+										  }
+										}
+									`),
+								},
+							},
+						},
+					},
+					Spec: v1.PodSpec{
+						NodeName: "node-1",
+					},
+				}
+			},
+			expected: true,
+		},
 		{
 			name: "with changes on Labels",
 			pod: &v1.Pod{