AllowExpandedDNSConfig if haveSameExpandedDNSConfig(newPod, oldPod)

pkg/api/pod/util.go

@@ -390,6 +390,37 @@ func usesIndivisibleHugePagesValues(podSpec *api.PodSpec) bool {
 	return false
 }
 
+// haveSameExpandedDNSConfig returns true if the oldPodSpec already had
+// ExpandedDNSConfig and podSpec has the same DNSConfig
+func haveSameExpandedDNSConfig(podSpec, oldPodSpec *api.PodSpec) bool {
+	if oldPodSpec == nil || oldPodSpec.DNSConfig == nil {
+		return false
+	}
+	if podSpec == nil || podSpec.DNSConfig == nil {
+		return false
+	}
+
+	if len(oldPodSpec.DNSConfig.Searches) <= apivalidation.MaxDNSSearchPathsLegacy &&
+		len(strings.Join(oldPodSpec.DNSConfig.Searches, " ")) <= apivalidation.MaxDNSSearchListCharsLegacy {
+		// didn't have ExpandedDNSConfig
+		return false
+	}
+
+	if len(oldPodSpec.DNSConfig.Searches) != len(podSpec.DNSConfig.Searches) {
+		// updates DNSConfig
+		return false
+	}
+
+	for i, oldSearch := range oldPodSpec.DNSConfig.Searches {
+		if podSpec.DNSConfig.Searches[i] != oldSearch {
+			// updates DNSConfig
+			return false
+		}
+	}
+
+	return true
+}
+
 // GetValidationOptionsFromPodSpecAndMeta returns validation options based on pod specs and metadata
 func GetValidationOptionsFromPodSpecAndMeta(podSpec, oldPodSpec *api.PodSpec, podMeta, oldPodMeta *metav1.ObjectMeta) apivalidation.PodValidationOptions {
 	// default pod validation options based on feature gate
@@ -403,7 +434,7 @@ func GetValidationOptionsFromPodSpecAndMeta(podSpec, oldPodSpec *api.PodSpec, po
 		AllowIndivisibleHugePagesValues: false,
 		AllowWindowsHostProcessField:    utilfeature.DefaultFeatureGate.Enabled(features.WindowsHostProcessContainers),
 		// Allow pod spec with expanded DNS configuration
-		AllowExpandedDNSConfig: utilfeature.DefaultFeatureGate.Enabled(features.ExpandedDNSConfig),
+		AllowExpandedDNSConfig: utilfeature.DefaultFeatureGate.Enabled(features.ExpandedDNSConfig) || haveSameExpandedDNSConfig(podSpec, oldPodSpec),
 	}
 
 	if oldPodSpec != nil {

pkg/api/pod/util_test.go

@@ -1474,6 +1474,365 @@ func TestValidatePodDeletionCostOption(t *testing.T) {
 	}
 }
 
+func TestHaveSameExpandedDNSConfig(t *testing.T) {
+	testCases := []struct {
+		desc       string
+		podSpec    *api.PodSpec
+		oldPodSpec *api.PodSpec
+		want       bool
+	}{
+		{
+			desc:       "nil DNSConfig",
+			podSpec:    &api.PodSpec{},
+			oldPodSpec: &api.PodSpec{},
+			want:       false,
+		},
+		{
+			desc: "empty DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{},
+			},
+			want: false,
+		},
+		{
+			desc: "same legacy DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			want: false,
+		},
+		{
+			desc: "update legacy DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"baz.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			want: false,
+		},
+		{
+			desc: "same expanded DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"7.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"7.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			want: true,
+		},
+		{
+			desc: "update expanded DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"baz.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"7.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			want: false,
+		},
+		{
+			desc: "update to legacy DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"baz.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"7.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			want: false,
+		},
+		{
+			desc: "update to expanded DNSConfig",
+			podSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+						"baz.expanded.com",
+						"8.expanded.com",
+						"9.expanded.com",
+						"10.expanded.com",
+						"11.expanded.com",
+						"12.expanded.com",
+						"13.expanded.com",
+						"14.expanded.com",
+						"15.expanded.com",
+						"16.expanded.com",
+						"17.expanded.com",
+						"18.expanded.com",
+						"19.expanded.com",
+						"20.expanded.com",
+						"21.expanded.com",
+						"22.expanded.com",
+						"23.expanded.com",
+						"24.expanded.com",
+						"25.expanded.com",
+						"26.expanded.com",
+						"27.expanded.com",
+						"28.expanded.com",
+						"29.expanded.com",
+						"30.expanded.com",
+						"31.expanded.com",
+						"32.expanded.com",
+					},
+				},
+			},
+			oldPodSpec: &api.PodSpec{
+				DNSConfig: &api.PodDNSConfig{
+					Searches: []string{
+						"foo.com",
+						"bar.io",
+						"3.com",
+						"4.com",
+						"5.com",
+						"6.com",
+					},
+				},
+			},
+			want: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			got := haveSameExpandedDNSConfig(tc.podSpec, tc.oldPodSpec)
+			if tc.want != got {
+				t.Errorf("unexpected diff, want: %v, got: %v", tc.want, got)
+			}
+		})
+	}
+}
+
 func TestDropDisabledPodAffinityTermFields(t *testing.T) {
 	testCases := []struct {
 		name        string