Support new labels zone, region, OS, Arch (#70)

* Support new labels zone, region, OS, Arch while scaling up machines from zero.

The old nodes label (zone, region, OS, Arch) was deprecated in favor of stable labels. This PR addresses this issue.
See: https://v1-18.docs.kubernetes.io/docs/reference/kubernetes-api/labels-annotations-taints/#failure-domainbetakubernetesiozone

cluster-autoscaler/cloudprovider/mcm/mcm_manager.go

@@ -64,8 +64,6 @@ const (
 	conflictRetryInterval   = 5 * time.Second
 	// machinePriorityAnnotation is the annotation to set machine priority while deletion
 	machinePriorityAnnotation = "machinepriority.machine.sapcloud.io"
-	// labelForFailureDomain is the label for failure domain used by kubernetes.io
-	labelForFailureDomain = "failure-domain.beta.kubernetes.io/zone"
 	// kindAWSMachineClass is the kind for machine class used by In-tree AWS provider
 	kindAWSMachineClass = "AWSMachineClass"
 	// kindAzureMachineClass is the kind for machine class used by In-tree Azure provider
@@ -441,10 +439,15 @@ func (m *McmManager) GetMachineDeploymentNodeTemplate(machinedeployment *Machine
 		return nil, fmt.Errorf("Unable to fetch MachineDeployment object %s, Error: %v", machinedeployment.Name, err)
 	}
 
-	var region, zone string
-	var instance instanceType
-	machineClass := md.Spec.Template.Spec.Class
-	nodeTemplateSpec := md.Spec.Template.Spec.NodeTemplateSpec
+	var (
+		region   string
+		zone     string
+		instance instanceType
+
+		machineClass     = md.Spec.Template.Spec.Class
+		nodeTemplateSpec = md.Spec.Template.Spec.NodeTemplateSpec
+	)
+
 	switch machineClass.Kind {
 	case kindAWSMachineClass:
 		mc, err := m.machineclient.AWSMachineClasses(m.namespace).Get(context.TODO(), machineClass.Name, metav1.GetOptions{})
@@ -459,9 +462,7 @@ func (m *McmManager) GetMachineDeploymentNodeTemplate(machinedeployment *Machine
 			GPU:          awsInstance.GPU,
 		}
 		region = mc.Spec.Region
-		if mc.Labels != nil {
-			zone = mc.Labels[labelForFailureDomain]
-		}
+		zone = getZoneValueFromMCLabels(mc.Labels)
 	case kindAzureMachineClass:
 		mc, err := m.machineclient.AzureMachineClasses(m.namespace).Get(context.TODO(), machineClass.Name, metav1.GetOptions{})
 		if err != nil {
@@ -499,9 +500,7 @@ func (m *McmManager) GetMachineDeploymentNodeTemplate(machinedeployment *Machine
 				GPU:          awsInstance.GPU,
 			}
 			region = providerSpec.Region
-			if mc.Labels != nil {
-				zone = mc.Labels[labelForFailureDomain]
-			}
+			zone = getZoneValueFromMCLabels(mc.Labels)
 		case providerAzure:
 			var providerSpec *azureapis.AzureProviderSpec
 			err = json.Unmarshal(mc.ProviderSpec.Raw, &providerSpec)
@@ -548,6 +547,22 @@ func (m *McmManager) GetMachineDeploymentNodeTemplate(machinedeployment *Machine
 	return nodeTmpl, nil
 }
 
+func getZoneValueFromMCLabels(labels map[string]string) string {
+	var zone string
+
+	if labels != nil {
+		if value, exists := labels[apiv1.LabelZoneFailureDomainStable]; exists {
+			// Prefer zone value from the new label
+			zone = value
+		} else if value, exists := labels[apiv1.LabelZoneFailureDomain]; exists {
+			// Fallback to zone value from deprecated label if new lable value doesn't exist
+			zone = value
+		}
+	}
+
+	return zone
+}
+
 func (m *McmManager) buildNodeFromTemplate(name string, template *nodeTemplate) (*apiv1.Node, error) {
 	node := apiv1.Node{}
 	nodeName := fmt.Sprintf("%s-%d", name, rand.Int63())
@@ -585,12 +600,20 @@ func buildGenericLabels(template *nodeTemplate, nodeName string) map[string]stri
 	result := make(map[string]string)
 	// TODO: extract from MCM
 	result[kubeletapis.LabelArch] = cloudprovider.DefaultArch
+	result[apiv1.LabelArchStable] = cloudprovider.DefaultArch
+
 	result[kubeletapis.LabelOS] = cloudprovider.DefaultOS
+	result[apiv1.LabelOSStable] = cloudprovider.DefaultOS
 
 	result[apiv1.LabelInstanceType] = template.InstanceType.InstanceType
+	result[apiv1.LabelInstanceTypeStable] = template.InstanceType.InstanceType
 
 	result[apiv1.LabelZoneRegion] = template.Region
+	result[apiv1.LabelZoneRegionStable] = template.Region
+
 	result[apiv1.LabelZoneFailureDomain] = template.Zone
+	result[apiv1.LabelZoneFailureDomainStable] = template.Zone
+
 	result[apiv1.LabelHostname] = nodeName
 	return result
 }

cluster-autoscaler/cloudprovider/mcm/mcm_manager_test.go

@@ -26,17 +26,73 @@ import (
 )
 
 func TestBuildGenericLabels(t *testing.T) {
+	var (
+		instanceTypeC4Large = "c4.large"
+		regionUSEast1       = "us-east-1"
+		zoneUSEast1a        = "us-east-1a"
+		testHostName        = "test-hostname"
+	)
+
 	labels := buildGenericLabels(&nodeTemplate{
 		InstanceType: &instanceType{
-			InstanceType: "c4.large",
+			InstanceType: instanceTypeC4Large,
 			VCPU:         2,
 			MemoryMb:     3840,
 		},
-		Region: "us-east-1",
-	}, "sillyname")
-	assert.Equal(t, "us-east-1", labels[apiv1.LabelZoneRegion])
-	assert.Equal(t, "sillyname", labels[apiv1.LabelHostname])
-	assert.Equal(t, "c4.large", labels[apiv1.LabelInstanceType])
+		Region: regionUSEast1,
+		Zone:   zoneUSEast1a,
+	}, testHostName)
+
 	assert.Equal(t, cloudprovider.DefaultArch, labels[kubeletapis.LabelArch])
+	assert.Equal(t, cloudprovider.DefaultArch, labels[apiv1.LabelArchStable])
+
 	assert.Equal(t, cloudprovider.DefaultOS, labels[kubeletapis.LabelOS])
+	assert.Equal(t, cloudprovider.DefaultOS, labels[apiv1.LabelOSStable])
+
+	assert.Equal(t, instanceTypeC4Large, labels[apiv1.LabelInstanceType])
+	assert.Equal(t, instanceTypeC4Large, labels[apiv1.LabelInstanceTypeStable])
+
+	assert.Equal(t, regionUSEast1, labels[apiv1.LabelZoneRegion])
+	assert.Equal(t, regionUSEast1, labels[apiv1.LabelZoneRegionStable])
+
+	assert.Equal(t, zoneUSEast1a, labels[apiv1.LabelZoneFailureDomain])
+	assert.Equal(t, zoneUSEast1a, labels[apiv1.LabelZoneFailureDomainStable])
+
+	assert.Equal(t, testHostName, labels[apiv1.LabelHostname])
+}
+
+func TestGenerationOfCorrectZoneValueFromMCLabel(t *testing.T) {
+	var (
+		resultingZone string
+		zoneA         = "zone-a"
+		zoneB         = "zone-b"
+		randomKey     = "random-key"
+		randomValue   = "random-value"
+	)
+
+	// Basic test to get zone value
+	resultingZone = getZoneValueFromMCLabels(map[string]string{
+		apiv1.LabelZoneFailureDomainStable: zoneA,
+	})
+	assert.Equal(t, resultingZone, zoneA)
+
+	// Prefer LabelZoneFailureDomainStable label over LabelZoneFailureDomain
+	resultingZone = getZoneValueFromMCLabels(map[string]string{
+		apiv1.LabelZoneFailureDomainStable: zoneA,
+		apiv1.LabelZoneFailureDomain:       zoneB,
+	})
+	assert.Equal(t, resultingZone, zoneA)
+
+	// Fallback to LabelZoneFailureDomain when LabelZoneFailureDomainStable is not found
+	resultingZone = getZoneValueFromMCLabels(map[string]string{
+		randomKey:                    randomValue,
+		apiv1.LabelZoneFailureDomain: zoneB,
+	})
+	assert.Equal(t, resultingZone, zoneB)
+
+	// When neither of the labels are found
+	resultingZone = getZoneValueFromMCLabels(map[string]string{
+		randomKey: randomValue,
+	})
+	assert.Equal(t, resultingZone, "")
 }