add label selector to DestinationRule subset config

networking/v1alpha3/destination_rule.proto

@@ -337,6 +337,8 @@ message Subset {
   // specified at the subset level will override the corresponding settings
   // specified at the DestinationRule level.
   TrafficPolicy traffic_policy = 3;
+
+  istio.type.v1beta1.LabelSelector selector = 4;
 }
 
 // Load balancing policies to apply for a specific destination. See Envoy's

type/v1beta1/selector.proto

@@ -129,3 +129,39 @@ message PolicyTargetReference {
   // +kubebuilder:validation:XValidation:message="cross namespace referencing is not currently supported",rule="self.size() == 0"
   string namespace = 4;
 }
+
+// A label selector requirement is a selector that contains values, a key, and an operator that
+// relates the key and values.
+// Copied from Kubernetes to avoid expensive dependency on Kubernetes libraries.
+message LabelSelector {
+  // matchLabels is a map of {key,value} pairs. A single {key,value} in the matchLabels
+  // map is equivalent to an element of matchExpressions, whose key field is "key", the
+  // operator is "In", and the values array contains only "value". The requirements are ANDed.
+  // +optional
+  map<string, string> matchLabels = 1;
+
+  // matchExpressions is a list of label selector requirements. The requirements are ANDed.
+  // +optional
+  repeated LabelSelectorRequirement matchExpressions = 2;
+}
+
+// A label selector requirement is a selector that contains values, a key, and an operator that
+// relates the key and values.
+// Copied from Kubernetes to avoid expensive dependency on Kubernetes libraries.
+message LabelSelectorRequirement {
+  // key is the label key that the selector applies to.
+  // +patchMergeKey=key
+  // +patchStrategy=merge
+  string key = 1;
+
+  // operator represents a key's relationship to a set of values.
+  // Valid operators are In, NotIn, Exists and DoesNotExist.
+  string operator = 2;
+
+  // values is an array of string values. If the operator is In or NotIn,
+  // the values array must be non-empty. If the operator is Exists or DoesNotExist,
+  // the values array must be empty. This array is replaced during a strategic
+  // merge patch.
+  // +optional
+  repeated string values = 3;
+}