Merge pull request #41617 from timothysc/affinity_annotations_flaggate

Automatic merge from submit-queue (batch tested with PRs 39373, 41585, 41617, 41707, 39958)

Feature-Gate affinity in annotations 

**What this PR does / why we need it**:
Adds back basic flaggated support for alpha Affinity annotations

**Special notes for your reviewer**:
Reconcile function is placed in the lowest common denominator, which in this case is schedulercache, because you can't place flag-gated functions in apimachinery. 

**Release note**:

```
NONE
```

/cc @davidopp

pkg/api/v1/helpers.go

@@ -277,6 +277,11 @@ const (
 	// an object (e.g. secret, config map) before fetching it again from apiserver.
 	// This annotation can be attached to node.
 	ObjectTTLAnnotationKey string = "node.alpha.kubernetes.io/ttl"
+
+	// AffinityAnnotationKey represents the key of affinity data (json serialized)
+	// in the Annotations of a Pod.
+	// TODO: remove when alpha support for affinity is removed
+	AffinityAnnotationKey string = "scheduler.alpha.kubernetes.io/affinity"
 )
 
 // GetTolerationsFromPodAnnotations gets the json serialized tolerations data from Pod.Annotations
@@ -646,3 +651,18 @@ func RemoveTaint(node *Node, taint *Taint) (*Node, bool, error) {
 	}
 	return newNode, true, nil
 }
+
+// GetAffinityFromPodAnnotations gets the json serialized affinity data from Pod.Annotations
+// and converts it to the Affinity type in api.
+// TODO: remove when alpha support for affinity is removed
+func GetAffinityFromPodAnnotations(annotations map[string]string) (*Affinity, error) {
+	if len(annotations) > 0 && annotations[AffinityAnnotationKey] != "" {
+		var affinity Affinity
+		err := json.Unmarshal([]byte(annotations[AffinityAnnotationKey]), &affinity)
+		if err != nil {
+			return nil, err
+		}
+		return &affinity, nil
+	}
+	return nil, nil
+}

pkg/api/v1/helpers_test.go

@@ -644,3 +644,60 @@ func TestSysctlsFromPodAnnotation(t *testing.T) {
 		}
 	}
 }
+
+// TODO: remove when alpha support for affinity is removed
+func TestGetAffinityFromPodAnnotations(t *testing.T) {
+	testCases := []struct {
+		pod       *Pod
+		expectErr bool
+	}{
+		{
+			pod:       &Pod{},
+			expectErr: false,
+		},
+		{
+			pod: &Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						AffinityAnnotationKey: `
+						{"nodeAffinity": { "requiredDuringSchedulingIgnoredDuringExecution": {
+							"nodeSelectorTerms": [{
+								"matchExpressions": [{
+									"key": "foo",
+									"operator": "In",
+									"values": ["value1", "value2"]
+								}]
+							}]
+						}}}`,
+					},
+				},
+			},
+			expectErr: false,
+		},
+		{
+			pod: &Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						AffinityAnnotationKey: `
+						{"nodeAffinity": { "requiredDuringSchedulingIgnoredDuringExecution": {
+							"nodeSelectorTerms": [{
+								"matchExpressions": [{
+									"key": "foo",
+						`,
+					},
+				},
+			},
+			expectErr: true,
+		},
+	}
+
+	for i, tc := range testCases {
+		_, err := GetAffinityFromPodAnnotations(tc.pod.Annotations)
+		if err == nil && tc.expectErr {
+			t.Errorf("[%v]expected error but got none.", i)
+		}
+		if err != nil && !tc.expectErr {
+			t.Errorf("[%v]did not expect error but got: %v", i, err)
+		}
+	}
+}