Add HPA status conditions to API types

This commit adds the new API status conditions to the API types.
The field exists as a field in autoscaling/v2alpha1, and is
round-tripped through an annotation in autoscaling/v1.

pkg/apis/autoscaling/annotations.go

@@ -24,6 +24,10 @@ const MetricSpecsAnnotation = "autoscaling.alpha.kubernetes.io/metrics"
 // statuses when converting the `CurrentMetrics` field from autoscaling/v2alpha1
 const MetricStatusesAnnotation = "autoscaling.alpha.kubernetes.io/current-metrics"
 
+// HorizontalPodAutoscalerConditionsAnnotation is the annotation which holds the conditions
+// of an HPA when converting the `Conditions` field from autoscaling/v2alpha1
+const HorizontalPodAutoscalerConditionsAnnotation = "autoscaling.alpha.kubernetes.io/conditions"
+
 // DefaultCPUUtilization is the default value for CPU utilization, provided no other
 // metrics are present.  This is here because it's used by both the v2alpha1 defaulting
 // logic, and the pseudo-defaulting done in v1 conversion.

pkg/apis/autoscaling/types.go

@@ -202,6 +202,59 @@ type HorizontalPodAutoscalerStatus struct {
 
 	// CurrentMetrics is the last read state of the metrics used by this autoscaler.
 	CurrentMetrics []MetricStatus
+
+	// Conditions is the set of conditions required for this autoscaler to scale its target,
+	// and indicates whether or not those conditions are met.
+	Conditions []HorizontalPodAutoscalerCondition
+}
+
+// ConditionStatus indicates the status of a condition (true, false, or unknown).
+type ConditionStatus string
+
+// These are valid condition statuses. "ConditionTrue" means a resource is in the condition;
+// "ConditionFalse" means a resource is not in the condition; "ConditionUnknown" means kubernetes
+// can't decide if a resource is in the condition or not. In the future, we could add other
+// intermediate conditions, e.g. ConditionDegraded.
+const (
+	ConditionTrue    ConditionStatus = "True"
+	ConditionFalse   ConditionStatus = "False"
+	ConditionUnknown ConditionStatus = "Unknown"
+)
+
+// HorizontalPodAutoscalerConditionType are the valid conditions of
+// a HorizontalPodAutoscaler.
+type HorizontalPodAutoscalerConditionType string
+
+var (
+	// ScalingActive indicates that the HPA controller is able to scale if necessary:
+	// it's correctly configured, can fetch the desired metrics, and isn't disabled.
+	ScalingActive HorizontalPodAutoscalerConditionType = "ScalingActive"
+	// AbleToScale indicates a lack of transient issues which prevent scaling from occuring,
+	// such as being in a backoff window, or being unable to access/update the target scale.
+	AbleToScale HorizontalPodAutoscalerConditionType = "AbleToScale"
+	// ScalingLimited indicates that the calculated scale based on metrics would be above or
+	// below the range for the HPA, and has thus been capped.
+	ScalingLimited HorizontalPodAutoscalerConditionType = "ScalingLimited"
+)
+
+// HorizontalPodAutoscalerCondition describes the state of
+// a HorizontalPodAutoscaler at a certain point.
+type HorizontalPodAutoscalerCondition struct {
+	// Type describes the current condition
+	Type HorizontalPodAutoscalerConditionType
+	// Status is the status of the condition (True, False, Unknown)
+	Status ConditionStatus
+	// LastTransitionTime is the last time the condition transitioned from
+	// one status to another
+	// +optional
+	LastTransitionTime metav1.Time
+	// Reason is the reason for the condition's last transition.
+	// +optional
+	Reason string
+	// Message is a human-readable explanation containing details about
+	// the transition
+	// +optional
+	Message string
 }
 
 // MetricStatus describes the last-read state of a single metric.

pkg/apis/autoscaling/v1/conversion.go

@@ -68,9 +68,17 @@ func Convert_autoscaling_HorizontalPodAutoscaler_To_v1_HorizontalPodAutoscaler(i
 		}
 	}
 
-	if len(otherMetrics) > 0 || len(in.Status.CurrentMetrics) > 0 {
+	// store HPA conditions in an annotation
+	currentConditions := make([]HorizontalPodAutoscalerCondition, len(in.Status.Conditions))
+	for i, currentCondition := range in.Status.Conditions {
+		if err := Convert_autoscaling_HorizontalPodAutoscalerCondition_To_v1_HorizontalPodAutoscalerCondition(&currentCondition, &currentConditions[i], s); err != nil {
+			return err
+		}
+	}
+
+	if len(otherMetrics) > 0 || len(in.Status.CurrentMetrics) > 0 || len(currentConditions) > 0 {
 		old := out.Annotations
-		out.Annotations = make(map[string]string, len(old)+2)
+		out.Annotations = make(map[string]string, len(old)+3)
 		if old != nil {
 			for k, v := range old {
 				out.Annotations[k] = v
@@ -94,6 +102,14 @@ func Convert_autoscaling_HorizontalPodAutoscaler_To_v1_HorizontalPodAutoscaler(i
 		out.Annotations[autoscaling.MetricStatusesAnnotation] = string(currentMetricsEnc)
 	}
 
+	if len(in.Status.Conditions) > 0 {
+		currentConditionsEnc, err := json.Marshal(currentConditions)
+		if err != nil {
+			return err
+		}
+		out.Annotations[autoscaling.HorizontalPodAutoscalerConditionsAnnotation] = string(currentConditionsEnc)
+	}
+
 	return nil
 }
 
@@ -154,6 +170,21 @@ func Convert_v1_HorizontalPodAutoscaler_To_autoscaling_HorizontalPodAutoscaler(i
 		*out.Spec.Metrics[0].Resource.TargetAverageUtilization = autoscaling.DefaultCPUUtilization
 	}
 
+	if currentConditionsEnc, hasCurrentConditions := out.Annotations[autoscaling.HorizontalPodAutoscalerConditionsAnnotation]; hasCurrentConditions {
+		var currentConditions []HorizontalPodAutoscalerCondition
+		if err := json.Unmarshal([]byte(currentConditionsEnc), &currentConditions); err != nil {
+			return err
+		}
+
+		out.Status.Conditions = make([]autoscaling.HorizontalPodAutoscalerCondition, len(currentConditions))
+		for i, currentCondition := range currentConditions {
+			if err := Convert_v1_HorizontalPodAutoscalerCondition_To_autoscaling_HorizontalPodAutoscalerCondition(&currentCondition, &out.Status.Conditions[i], s); err != nil {
+				return err
+			}
+		}
+		delete(out.Annotations, autoscaling.HorizontalPodAutoscalerConditionsAnnotation)
+	}
+
 	return nil
 }
 

pkg/apis/autoscaling/v1/types.go

@@ -251,6 +251,42 @@ type MetricStatus struct {
 	Resource *ResourceMetricStatus `json:"resource,omitempty" protobuf:"bytes,4,opt,name=resource"`
 }
 
+// HorizontalPodAutoscalerConditionType are the valid conditions of
+// a HorizontalPodAutoscaler.
+type HorizontalPodAutoscalerConditionType string
+
+var (
+	// ScalingActive indicates that the HPA controller is able to scale if necessary:
+	// it's correctly configured, can fetch the desired metrics, and isn't disabled.
+	ScalingActive HorizontalPodAutoscalerConditionType = "ScalingActive"
+	// AbleToScale indicates a lack of transient issues which prevent scaling from occuring,
+	// such as being in a backoff window, or being unable to access/update the target scale.
+	AbleToScale HorizontalPodAutoscalerConditionType = "AbleToScale"
+	// ScalingLimited indicates that the calculated scale based on metrics would be above or
+	// below the range for the HPA, and has thus been capped.
+	ScalingLimited HorizontalPodAutoscalerConditionType = "ScalingLimited"
+)
+
+// HorizontalPodAutoscalerCondition describes the state of
+// a HorizontalPodAutoscaler at a certain point.
+type HorizontalPodAutoscalerCondition struct {
+	// type describes the current condition
+	Type HorizontalPodAutoscalerConditionType `json:"type" protobuf:"bytes,1,name=type"`
+	// status is the status of the condition (True, False, Unknown)
+	Status v1.ConditionStatus `json:"status" protobuf:"bytes,2,name=status"`
+	// lastTransitionTime is the last time the condition transitioned from
+	// one status to another
+	// +optional
+	LastTransitionTime metav1.Time `json:"lastTransitionTime,omitempty" protobuf:"bytes,3,opt,name=lastTransitionTime"`
+	// reason is the reason for the condition's last transition.
+	// +optional
+	Reason string `json:"reason,omitempty" protobuf:"bytes,4,opt,name=reason"`
+	// message is a human-readable explanation containing details about
+	// the transition
+	// +optional
+	Message string `json:"message,omitempty" protobuf:"bytes,5,opt,name=message"`
+}
+
 // ObjectMetricStatus indicates the current value of a metric describing a
 // kubernetes object (for example, hits-per-second on an Ingress object).
 type ObjectMetricStatus struct {

pkg/apis/autoscaling/v2alpha1/types.go

@@ -166,6 +166,46 @@ type HorizontalPodAutoscalerStatus struct {
 
 	// currentMetrics is the last read state of the metrics used by this autoscaler.
 	CurrentMetrics []MetricStatus `json:"currentMetrics" protobuf:"bytes,5,rep,name=currentMetrics"`
+
+	// conditions is the set of conditions required for this autoscaler to scale its target,
+	// and indicates whether or not those conditions are met.
+	Conditions []HorizontalPodAutoscalerCondition `json:"conditions" protobuf:"bytes,6,rep,name=conditions"`
+}
+
+// HorizontalPodAutoscalerConditionType are the valid conditions of
+// a HorizontalPodAutoscaler.
+type HorizontalPodAutoscalerConditionType string
+
+var (
+	// ScalingActive indicates that the HPA controller is able to scale if necessary:
+	// it's correctly configured, can fetch the desired metrics, and isn't disabled.
+	ScalingActive HorizontalPodAutoscalerConditionType = "ScalingActive"
+	// AbleToScale indicates a lack of transient issues which prevent scaling from occuring,
+	// such as being in a backoff window, or being unable to access/update the target scale.
+	AbleToScale HorizontalPodAutoscalerConditionType = "AbleToScale"
+	// ScalingLimited indicates that the calculated scale based on metrics would be above or
+	// below the range for the HPA, and has thus been capped.
+	ScalingLimited HorizontalPodAutoscalerConditionType = "ScalingLimited"
+)
+
+// HorizontalPodAutoscalerCondition describes the state of
+// a HorizontalPodAutoscaler at a certain point.
+type HorizontalPodAutoscalerCondition struct {
+	// type describes the current condition
+	Type HorizontalPodAutoscalerConditionType `json:"type" protobuf:"bytes,1,name=type"`
+	// status is the status of the condition (True, False, Unknown)
+	Status v1.ConditionStatus `json:"status" protobuf:"bytes,2,name=status"`
+	// lastTransitionTime is the last time the condition transitioned from
+	// one status to another
+	// +optional
+	LastTransitionTime metav1.Time `json:"lastTransitionTime,omitempty" protobuf:"bytes,3,opt,name=lastTransitionTime"`
+	// reason is the reason for the condition's last transition.
+	// +optional
+	Reason string `json:"reason,omitempty" protobuf:"bytes,4,opt,name=reason"`
+	// message is a human-readable explanation containing details about
+	// the transition
+	// +optional
+	Message string `json:"message,omitempty" protobuf:"bytes,5,opt,name=message"`
 }
 
 // MetricStatus describes the last-read state of a single metric.