Address some comments

Signed-off-by: Wenqi Qiu <wenqiq@vmware.com>

docs/antrea-network-policy.md

@@ -34,6 +34,7 @@
   - [K8s clusters with version 1.21 and above](#k8s-clusters-with-version-121-and-above)
   - [K8s clusters with version 1.20 and below](#k8s-clusters-with-version-120-and-below)
 - [FQDN based filtering](#fqdn-based-filtering)
+- [Node Selector](#node-selector)
 - [toServices instruction](#toservices-instruction)
 - [RBAC](#rbac)
 - [Notes](#notes)
@@ -491,7 +492,7 @@ Usage of ClusterGroups along with stand-alone selectors is not allowed.
 
 ### Behavior of *to* and *from* selectors
 
-There are six kinds of selectors that can be specified in an ingress `from`
+There are seven kinds of selectors that can be specified in an ingress `from`
 section or egress `to` section:
 
 **podSelector**: This selects particular Pods from all Namespaces as "sources",
@@ -505,6 +506,10 @@ with `namespaces` field.
 specifies both namespaceSelector and podSelector selects particular Pods within
 particular Namespaces.
 
+**nodeSelector**: This selects particular Nodes in cluster.
+The selected Node's IPs will set as "sources" if `nodeSelector` set in `ingress` section, or as "destinations" if set in
+`egress` section.
+
 **namespaces**: A `namespaces` field allows users to perform advanced matching on
 Namespace objects which cannot be done via label selectors. Currently, the
 `namespaces` field has only one matching strategy, `self`. If set to `self`, it indicates
@@ -526,9 +531,6 @@ since Pod IPs are ephemeral and unpredictable.
 select Fully Qualified Domain Names (FQDNs), specified either by exact name or wildcard
 expressions, when defining `egress` rules.
 
-**nodeSelector**: This selects certain Node IPs as ingress from address or egress to address.
-It is applicable only to the `from` section in an `ingress` block or the `to` section in an `egress` block.
-
 ### Key differences from K8s NetworkPolicy
 
 - ClusterNetworkPolicy is at the cluster scope, hence a `podSelector` without
@@ -1067,9 +1069,11 @@ spec:
 
 ## Node Selector 
 
-NodeSelector selects certain Nodes which match the label selector. Add Node IPs to address group memberSet.
-The following rule applied to Pods with label `app=antrea-test-app` and will `Drop` egress traffic to 
-Nodes which has labels `kubernetes.io/hostname=kind-control-plane`.
+NodeSelector selects certain Nodes which match the label selector. It adds Node IPs to egress rules in `to` field
+or ingress rules in `from` filed.
+The following rule applies to Pods with label `app=antrea-test-app` and will `Drop` egress traffic to 
+Nodes which have the labels `node-role.kubernetes.io/control-plane`.
+
 ```yaml
 apiVersion: crd.antrea.io/v1alpha1
 kind: ClusterNetworkPolicy
@@ -1085,11 +1089,8 @@ spec:
     - action: Drop
       to:
         - nodeSelector:
-            matchExpressions:
-              - key: kubernetes.io/hostname
-                operator: In
-                values:
-                  - kind-control-plane
+            matchLabels:
+              node-role.kubernetes.io/control-plane: ""
       ports:
         - protocol: TCP
           port: 6443

pkg/apis/crd/v1alpha1/types.go

@@ -15,7 +15,6 @@
 package v1alpha1
 
 import (
-	_ "github.com/golang/mock/mockgen/model"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/intstr"
@@ -436,8 +435,8 @@ type NetworkPolicyPeer struct {
 	//  Wildcard expressions, i.e. "*wayfair.com".
 	FQDN string `json:"fqdn,omitempty"`
 	// Select certain Nodes which match the label selector,
-	// if no nodeSelector is specified, then all Nodes will be selected
-	// in the cluster.
+	// if no nodeSelector is specified, then no additional Nodes IPs will be added
+	// in egress/ingress rules.
 	// +optional
 	NodeSelector *metav1.LabelSelector `json:"nodeSelector,omitempty"`
 }