From 249f763c7ee6033ebfe7c398879bac439017d30b Mon Sep 17 00:00:00 2001
From: Katarzyna Lach <katarzynalach@google.com>
Date: Fri, 23 Dec 2022 12:36:04 +0000
Subject: [PATCH] Generate warning for EndpointSlice AddressType FQDN

Change-Id: Ibc213acdffa741e630821f371ea25e2b5187a011
---
 pkg/apis/discovery/types.go                   |  2 +-
 .../discovery/endpointslice/strategy.go       | 17 ++++++++-
 .../discovery/endpointslice/strategy_test.go  | 36 +++++++++++++++++++
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/pkg/apis/discovery/types.go b/pkg/apis/discovery/types.go
index 8b4dc265a60..efc2d331ec9 100644
--- a/pkg/apis/discovery/types.go
+++ b/pkg/apis/discovery/types.go
@@ -37,7 +37,7 @@ type EndpointSlice struct {
 	// supported:
 	// * IPv4: Represents an IPv4 Address.
 	// * IPv6: Represents an IPv6 Address.
-	// * FQDN: Represents a Fully Qualified Domain Name.
+	// * FQDN: Represents a Fully Qualified Domain Name. [DEPRECATED]
 	AddressType AddressType
 	// endpoints is a list of unique endpoints in this slice. Each slice may
 	// include a maximum of 1000 endpoints.
diff --git a/pkg/registry/discovery/endpointslice/strategy.go b/pkg/registry/discovery/endpointslice/strategy.go
index 6bb8359f1e4..62571f294be 100644
--- a/pkg/registry/discovery/endpointslice/strategy.go
+++ b/pkg/registry/discovery/endpointslice/strategy.go
@@ -18,6 +18,7 @@ package endpointslice
 
 import (
 	"context"
+	"fmt"
 
 	corev1 "k8s.io/api/core/v1"
 	discoveryv1beta1 "k8s.io/api/discovery/v1beta1"
@@ -92,7 +93,13 @@ func (endpointSliceStrategy) Validate(ctx context.Context, obj runtime.Object) f
 
 // WarningsOnCreate returns warnings for the creation of the given object.
 func (endpointSliceStrategy) WarningsOnCreate(ctx context.Context, obj runtime.Object) []string {
-	return nil
+	eps := obj.(*discovery.EndpointSlice)
+	if eps == nil {
+		return nil
+	}
+	var warnings []string
+	warnings = append(warnings, warnOnDeprecatedAddressType(eps.AddressType)...)
+	return warnings
 }
 
 // Canonicalize normalizes the object after validation.
@@ -207,3 +214,11 @@ func getDeprecatedTopologyNodeNames(eps *discovery.EndpointSlice) sets.String {
 	}
 	return names
 }
+
+// warnOnDeprecatedAddressType returns a warning for endpointslices with FQDN AddressType
+func warnOnDeprecatedAddressType(addressType discovery.AddressType) []string {
+	if addressType == discovery.AddressTypeFQDN {
+		return []string{fmt.Sprintf("%s: FQDN endpoints are deprecated", field.NewPath("spec").Child("addressType"))}
+	}
+	return nil
+}
diff --git a/pkg/registry/discovery/endpointslice/strategy_test.go b/pkg/registry/discovery/endpointslice/strategy_test.go
index 6204fe5af62..b0158abca03 100644
--- a/pkg/registry/discovery/endpointslice/strategy_test.go
+++ b/pkg/registry/discovery/endpointslice/strategy_test.go
@@ -978,3 +978,39 @@ func Test_getDeprecatedTopologyNodeNames(t *testing.T) {
 		})
 	}
 }
+
+func TestWarningsOnEndpointSliceAddressType(t *testing.T) {
+	tests := []struct {
+		name        string
+		addressType discovery.AddressType
+		wantWarning bool
+	}{
+		{
+			name:        "AddressType = FQDN",
+			addressType: discovery.AddressTypeFQDN,
+			wantWarning: true,
+		},
+		{
+			name:        "AddressType = IPV4",
+			addressType: discovery.AddressTypeIPv4,
+			wantWarning: false,
+		},
+		{
+			name:        "AddressType = IPV6",
+			addressType: discovery.AddressTypeIPv6,
+			wantWarning: false,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx := genericapirequest.WithRequestInfo(genericapirequest.NewContext(), &genericapirequest.RequestInfo{APIGroup: "discovery.k8s.io", APIVersion: "v1", Resource: "endpointslices"})
+			edp := discovery.EndpointSlice{AddressType: tc.addressType}
+			got := Strategy.WarningsOnCreate(ctx, &edp)
+			if tc.wantWarning && len(got) == 0 {
+				t.Fatal("Failed warning was not returned")
+			} else if !tc.wantWarning && len(got) != 0 {
+				t.Fatalf("Failed warning  was returned (%v)", got)
+			}
+		})
+	}
+}