Merge pull request #43271 from liggitt/affinity-namespace

Automatic merge from submit-queue (batch tested with PRs 43313, 43257, 43271, 43307)

Remove 'all namespaces' meaning of empty list in PodAffinityTerm

Removes the distinction between `null` and `[]` for the PodAffinityTerm#namespaces field (option 4 discussed in https://github.com/kubernetes/kubernetes/issues/43203#issuecomment-287237992), since we can't distinguish between them in protobuf (and it's a less than ideal API)

Leaves the door open to reintroducing "all namespaces" function via a dedicated field or a dedicated token in the list of namespaces

Wanted to get a PR open and tests green in case we went with this option.

Not sure what doc/release-note is needed if the "all namespaces" function is not present in 1.6

api/openapi-spec/swagger.json

@@ -39818,16 +39818,13 @@
    },
    "io.k8s.kubernetes.pkg.api.v1.PodAffinityTerm": {
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "description": "A label query over a set of resources, in this case pods.",
       "$ref": "#/definitions/io.k8s.apimachinery.pkg.apis.meta.v1.LabelSelector"
      },
      "namespaces": {
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details.",
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\"",
       "type": "array",
       "items": {
        "type": "string"

api/swagger-spec/apps_v1beta1.json

@@ -4259,9 +4259,6 @@
    "v1.PodAffinityTerm": {
     "id": "v1.PodAffinityTerm",
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "$ref": "v1.LabelSelector",
@@ -4272,7 +4269,7 @@
       "items": {
        "type": "string"
       },
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details."
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\""
      },
      "topologyKey": {
       "type": "string",

api/swagger-spec/batch_v1.json

@@ -3042,9 +3042,6 @@
    "v1.PodAffinityTerm": {
     "id": "v1.PodAffinityTerm",
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "$ref": "v1.LabelSelector",
@@ -3055,7 +3052,7 @@
       "items": {
        "type": "string"
       },
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details."
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\""
      },
      "topologyKey": {
       "type": "string",

api/swagger-spec/extensions_v1beta1.json

@@ -8506,9 +8506,6 @@
    "v1.PodAffinityTerm": {
     "id": "v1.PodAffinityTerm",
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "$ref": "v1.LabelSelector",
@@ -8519,7 +8516,7 @@
       "items": {
        "type": "string"
       },
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details."
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\""
      },
      "topologyKey": {
       "type": "string",

api/swagger-spec/v1.json

@@ -19857,9 +19857,6 @@
    "v1.PodAffinityTerm": {
     "id": "v1.PodAffinityTerm",
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "$ref": "v1.LabelSelector",
@@ -19870,7 +19867,7 @@
       "items": {
        "type": "string"
       },
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details."
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\""
      },
      "topologyKey": {
       "type": "string",

docs/api-reference/apps/v1beta1/definitions.html

@@ -1984,8 +1984,8 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 </tr>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">namespaces</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means "this pod&#8217;s namespace," empty list means "all namespaces" The json tag here is not "omitempty" since we need to distinguish nil and empty. See <a href="https://golang.org/pkg/encoding/json/#Marshal">https://golang.org/pkg/encoding/json/#Marshal</a> for more details.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means "this pod&#8217;s namespace"</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">true</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">string array</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>

docs/api-reference/batch/v1/definitions.html

@@ -2818,8 +2818,8 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 </tr>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">namespaces</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means "this pod&#8217;s namespace," empty list means "all namespaces" The json tag here is not "omitempty" since we need to distinguish nil and empty. See <a href="https://golang.org/pkg/encoding/json/#Marshal">https://golang.org/pkg/encoding/json/#Marshal</a> for more details.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means "this pod&#8217;s namespace"</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">true</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">string array</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>

docs/api-reference/extensions/v1beta1/definitions.html

@@ -2604,8 +2604,8 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 </tr>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">namespaces</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means "this pod&#8217;s namespace," empty list means "all namespaces" The json tag here is not "omitempty" since we need to distinguish nil and empty. See <a href="https://golang.org/pkg/encoding/json/#Marshal">https://golang.org/pkg/encoding/json/#Marshal</a> for more details.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means "this pod&#8217;s namespace"</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">true</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">string array</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>

docs/api-reference/v1/definitions.html

@@ -2737,8 +2737,8 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 </tr>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">namespaces</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means "this pod&#8217;s namespace," empty list means "all namespaces" The json tag here is not "omitempty" since we need to distinguish nil and empty. See <a href="https://golang.org/pkg/encoding/json/#Marshal">https://golang.org/pkg/encoding/json/#Marshal</a> for more details.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means "this pod&#8217;s namespace"</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">true</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">string array</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>

federation/apis/openapi-spec/swagger.json

@@ -10586,16 +10586,13 @@
    },
    "io.k8s.kubernetes.pkg.api.v1.PodAffinityTerm": {
     "description": "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key \u003ctopologyKey\u003e tches that of any node on which a pod of the set of pods is running",
-    "required": [
-     "namespaces"
-    ],
     "properties": {
      "labelSelector": {
       "description": "A label query over a set of resources, in this case pods.",
       "$ref": "#/definitions/io.k8s.apimachinery.pkg.apis.meta.v1.LabelSelector"
      },
      "namespaces": {
-      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details.",
+      "description": "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\"",
       "type": "array",
       "items": {
        "type": "string"

pkg/api/types.go

@@ -1886,9 +1886,7 @@ type PodAffinityTerm struct {
 	// +optional
 	LabelSelector *metav1.LabelSelector
 	// namespaces specifies which namespaces the labelSelector applies to (matches against);
-	// nil list means "this pod's namespace," empty list means "all namespaces"
+	// null or empty list means "this pod's namespace"
-	// The json tag here is not "omitempty" since we need to distinguish nil and empty.
-	// See https://golang.org/pkg/encoding/json/#Marshal for more details.
 	Namespaces []string
 	// This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching
 	// the labelSelector in the specified namespaces, where co-located is defined as running on a node

pkg/api/v1/generated.proto

@@ -2279,9 +2279,7 @@ message PodAffinityTerm {
   optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector labelSelector = 1;
 
   // namespaces specifies which namespaces the labelSelector applies to (matches against);
-  // nil list means "this pod's namespace," empty list means "all namespaces"
+  // null or empty list means "this pod's namespace"
-  // The json tag here is not "omitempty" since we need to distinguish nil and empty.
-  // See https://golang.org/pkg/encoding/json/#Marshal for more details.
   repeated string namespaces = 2;
 
   // This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching

pkg/api/v1/types.generated.go

@@ -32190,12 +32190,13 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 			_, _, _ = yysep2, yyq2, yy2arr2
 			const yyr2 bool = false
 			yyq2[0] = x.LabelSelector != nil
+			yyq2[1] = len(x.Namespaces) != 0
 			yyq2[2] = x.TopologyKey != ""
 			var yynn2 int
 			if yyr2 || yy2arr2 {
 				r.EncodeArrayStart(3)
 			} else {
-				yynn2 = 1
+				yynn2 = 0
 				for _, b := range yyq2 {
 					if b {
 						yynn2++
@@ -32241,6 +32242,7 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
+				if yyq2[1] {
 					if x.Namespaces == nil {
 						r.EncodeNil()
 					} else {
@@ -32252,6 +32254,10 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 						}
 					}
 				} else {
+					r.EncodeNil()
+				}
+			} else {
+				if yyq2[1] {
 					z.EncSendContainerState(codecSelfer_containerMapKey1234)
 					r.EncodeString(codecSelferC_UTF81234, string("namespaces"))
 					z.EncSendContainerState(codecSelfer_containerMapValue1234)
@@ -32266,6 +32272,7 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 						}
 					}
 				}
+			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
 				if yyq2[2] {

pkg/api/v1/types.go

@@ -2102,10 +2102,8 @@ type PodAffinityTerm struct {
 	// +optional
 	LabelSelector *metav1.LabelSelector `json:"labelSelector,omitempty" protobuf:"bytes,1,opt,name=labelSelector"`
 	// namespaces specifies which namespaces the labelSelector applies to (matches against);
-	// nil list means "this pod's namespace," empty list means "all namespaces"
+	// null or empty list means "this pod's namespace"
-	// The json tag here is not "omitempty" since we need to distinguish nil and empty.
+	Namespaces []string `json:"namespaces,omitempty" protobuf:"bytes,2,rep,name=namespaces"`
-	// See https://golang.org/pkg/encoding/json/#Marshal for more details.
-	Namespaces []string `json:"namespaces" protobuf:"bytes,2,rep,name=namespaces"`
 	// This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching
 	// the labelSelector in the specified namespaces, where co-located is defined as running on a node
 	// whose value of the label with key topologyKey matches that of any node on which any of the

pkg/api/v1/types_swagger_doc_generated.go

@@ -1189,7 +1189,7 @@ func (PodAffinity) SwaggerDoc() map[string]string {
 var map_PodAffinityTerm = map[string]string{
 	"":              "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key <topologyKey> tches that of any node on which a pod of the set of pods is running",
 	"labelSelector": "A label query over a set of resources, in this case pods.",
-	"namespaces":    "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details.",
+	"namespaces":    "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\"",
 	"topologyKey":   "This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching the labelSelector in the specified namespaces, where co-located is defined as running on a node whose value of the label with key topologyKey matches that of any node on which any of the selected pods is running. For PreferredDuringScheduling pod anti-affinity, empty topologyKey is interpreted as \"all topologies\" (\"all topologies\" here means all the topologyKeys indicated by scheduler command-line argument --failure-domains); for affinity and for RequiredDuringScheduling pod anti-affinity, empty topologyKey is not allowed.",
 }
 

pkg/generated/openapi/zz_generated.openapi.go

@@ -5925,7 +5925,7 @@ func GetOpenAPIDefinitions(ref openapi.ReferenceCallback) map[string]openapi.Ope
 						},
 						"namespaces": {
 							SchemaProps: spec.SchemaProps{
-								Description: "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details.",
+								Description: "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\"",
 								Type:        []string{"array"},
 								Items: &spec.SchemaOrArray{
 									Schema: &spec.Schema{
@@ -5945,7 +5945,6 @@ func GetOpenAPIDefinitions(ref openapi.ReferenceCallback) map[string]openapi.Ope
 							},
 						},
 					},
-					Required: []string{"namespaces"},
 				},
 			},
 			Dependencies: []string{

plugin/pkg/scheduler/algorithm/priorities/util/topologies.go

@@ -26,13 +26,12 @@ import (
 
 // GetNamespacesFromPodAffinityTerm returns a set of names
 // according to the namespaces indicated in podAffinityTerm.
-// 1. If the namespaces is nil considers the given pod's namespace
+// If namespaces is empty it considers the given pod's namespace.
-// 2. If the namespaces is empty list then considers all the namespaces
 func GetNamespacesFromPodAffinityTerm(pod *v1.Pod, podAffinityTerm *v1.PodAffinityTerm) sets.String {
 	names := sets.String{}
-	if podAffinityTerm.Namespaces == nil {
+	if len(podAffinityTerm.Namespaces) == 0 {
 		names.Insert(pod.Namespace)
-	} else if len(podAffinityTerm.Namespaces) != 0 {
+	} else {
 		names.Insert(podAffinityTerm.Namespaces...)
 	}
 	return names
@@ -41,7 +40,7 @@ func GetNamespacesFromPodAffinityTerm(pod *v1.Pod, podAffinityTerm *v1.PodAffini
 // PodMatchesTermsNamespaceAndSelector returns true if the given <pod>
 // matches the namespace and selector defined by <affinityPod>`s <term>.
 func PodMatchesTermsNamespaceAndSelector(pod *v1.Pod, namespaces sets.String, selector labels.Selector) bool {
-	if len(namespaces) != 0 && !namespaces.Has(pod.Namespace) {
+	if !namespaces.Has(pod.Namespace) {
 		return false
 	}
 

staging/src/k8s.io/client-go/pkg/api/types.go

@@ -1886,9 +1886,7 @@ type PodAffinityTerm struct {
 	// +optional
 	LabelSelector *metav1.LabelSelector
 	// namespaces specifies which namespaces the labelSelector applies to (matches against);
-	// nil list means "this pod's namespace," empty list means "all namespaces"
+	// null or empty list means "this pod's namespace"
-	// The json tag here is not "omitempty" since we need to distinguish nil and empty.
-	// See https://golang.org/pkg/encoding/json/#Marshal for more details.
 	Namespaces []string
 	// This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching
 	// the labelSelector in the specified namespaces, where co-located is defined as running on a node

staging/src/k8s.io/client-go/pkg/api/v1/generated.proto

@@ -2279,9 +2279,7 @@ message PodAffinityTerm {
   optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector labelSelector = 1;
 
   // namespaces specifies which namespaces the labelSelector applies to (matches against);
-  // nil list means "this pod's namespace," empty list means "all namespaces"
+  // null or empty list means "this pod's namespace"
-  // The json tag here is not "omitempty" since we need to distinguish nil and empty.
-  // See https://golang.org/pkg/encoding/json/#Marshal for more details.
   repeated string namespaces = 2;
 
   // This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching

staging/src/k8s.io/client-go/pkg/api/v1/types.generated.go

@@ -32190,12 +32190,13 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 			_, _, _ = yysep2, yyq2, yy2arr2
 			const yyr2 bool = false
 			yyq2[0] = x.LabelSelector != nil
+			yyq2[1] = len(x.Namespaces) != 0
 			yyq2[2] = x.TopologyKey != ""
 			var yynn2 int
 			if yyr2 || yy2arr2 {
 				r.EncodeArrayStart(3)
 			} else {
-				yynn2 = 1
+				yynn2 = 0
 				for _, b := range yyq2 {
 					if b {
 						yynn2++
@@ -32241,6 +32242,7 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
+				if yyq2[1] {
 					if x.Namespaces == nil {
 						r.EncodeNil()
 					} else {
@@ -32252,6 +32254,10 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 						}
 					}
 				} else {
+					r.EncodeNil()
+				}
+			} else {
+				if yyq2[1] {
 					z.EncSendContainerState(codecSelfer_containerMapKey1234)
 					r.EncodeString(codecSelferC_UTF81234, string("namespaces"))
 					z.EncSendContainerState(codecSelfer_containerMapValue1234)
@@ -32266,6 +32272,7 @@ func (x *PodAffinityTerm) CodecEncodeSelf(e *codec1978.Encoder) {
 						}
 					}
 				}
+			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
 				if yyq2[2] {

staging/src/k8s.io/client-go/pkg/api/v1/types.go

@@ -2102,10 +2102,8 @@ type PodAffinityTerm struct {
 	// +optional
 	LabelSelector *metav1.LabelSelector `json:"labelSelector,omitempty" protobuf:"bytes,1,opt,name=labelSelector"`
 	// namespaces specifies which namespaces the labelSelector applies to (matches against);
-	// nil list means "this pod's namespace," empty list means "all namespaces"
+	// null or empty list means "this pod's namespace"
-	// The json tag here is not "omitempty" since we need to distinguish nil and empty.
+	Namespaces []string `json:"namespaces,omitempty" protobuf:"bytes,2,rep,name=namespaces"`
-	// See https://golang.org/pkg/encoding/json/#Marshal for more details.
-	Namespaces []string `json:"namespaces" protobuf:"bytes,2,rep,name=namespaces"`
 	// This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching
 	// the labelSelector in the specified namespaces, where co-located is defined as running on a node
 	// whose value of the label with key topologyKey matches that of any node on which any of the

staging/src/k8s.io/client-go/pkg/api/v1/types_swagger_doc_generated.go

@@ -1189,7 +1189,7 @@ func (PodAffinity) SwaggerDoc() map[string]string {
 var map_PodAffinityTerm = map[string]string{
 	"":              "Defines a set of pods (namely those matching the labelSelector relative to the given namespace(s)) that this pod should be co-located (affinity) or not co-located (anti-affinity) with, where co-located is defined as running on a node whose value of the label with key <topologyKey> tches that of any node on which a pod of the set of pods is running",
 	"labelSelector": "A label query over a set of resources, in this case pods.",
-	"namespaces":    "namespaces specifies which namespaces the labelSelector applies to (matches against); nil list means \"this pod's namespace,\" empty list means \"all namespaces\" The json tag here is not \"omitempty\" since we need to distinguish nil and empty. See https://golang.org/pkg/encoding/json/#Marshal for more details.",
+	"namespaces":    "namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means \"this pod's namespace\"",
 	"topologyKey":   "This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching the labelSelector in the specified namespaces, where co-located is defined as running on a node whose value of the label with key topologyKey matches that of any node on which any of the selected pods is running. For PreferredDuringScheduling pod anti-affinity, empty topologyKey is interpreted as \"all topologies\" (\"all topologies\" here means all the topologyKeys indicated by scheduler command-line argument --failure-domains); for affinity and for RequiredDuringScheduling pod anti-affinity, empty topologyKey is not allowed.",
 }