cri: add deprecation warning for mirrors

Signed-off-by: Samuel Karp <samuelkarp@google.com>

pkg/cri/config/config.go

@@ -397,6 +397,7 @@ func ValidatePluginConfig(ctx context.Context, c *PluginConfig) ([]deprecation.W
 		if useConfigPath {
 			return warnings, errors.New("`mirrors` cannot be set when `config_path` is provided")
 		}
+		warnings = append(warnings, deprecation.CRIRegistryMirrors)
 		log.G(ctx).Warning("`mirrors` is deprecated, please use `config_path` instead")
 	}
 

pkg/cri/config/config_test.go

@@ -115,6 +115,37 @@ func TestValidateConfig(t *testing.T) {
 			},
 			expectedErr: "`mirrors` cannot be set when `config_path` is provided",
 		},
+		"deprecated mirrors": {
+			config: &PluginConfig{
+				ContainerdConfig: ContainerdConfig{
+					DefaultRuntimeName: RuntimeDefault,
+					Runtimes: map[string]Runtime{
+						RuntimeDefault: {},
+					},
+				},
+				Registry: Registry{
+					Mirrors: map[string]Mirror{
+						"example.com": {},
+					},
+				},
+			},
+			expected: &PluginConfig{
+				ContainerdConfig: ContainerdConfig{
+					DefaultRuntimeName: RuntimeDefault,
+					Runtimes: map[string]Runtime{
+						RuntimeDefault: {
+							Sandboxer: string(ModePodSandbox),
+						},
+					},
+				},
+				Registry: Registry{
+					Mirrors: map[string]Mirror{
+						"example.com": {},
+					},
+				},
+			},
+			warnings: []deprecation.Warning{deprecation.CRIRegistryMirrors},
+		},
 		"privileged_without_host_devices_all_devices_allowed without privileged_without_host_devices": {
 			config: &PluginConfig{
 				ContainerdConfig: ContainerdConfig{

pkg/deprecation/deprecation.go

@@ -25,12 +25,16 @@ const (
 	PullSchema1Image Warning = Prefix + "pull-schema-1-image"
 	// GoPluginLibrary is a warning for the use of dynamic library Go plugins
 	GoPluginLibrary Warning = Prefix + "go-plugin-library"
+	// CRIRegistryMirrors is a warning for the use of the `mirrors` property
+	CRIRegistryMirrors Warning = Prefix + "cri-registry-mirrors"
 )
 
 var messages = map[Warning]string{
 	PullSchema1Image: "Schema 1 images are deprecated since containerd v1.7 and removed in containerd v2.0. " +
 		`Since containerd v1.7.8, schema 1 images are identified by the "io.containerd.image/converted-docker-schema1" label.`,
 	GoPluginLibrary: "Dynamically-linked Go plugins as containerd runtimes are deprecated since containerd v2.0 and removed in containerd v2.1.",
+	CRIRegistryMirrors: "The `mirrors` property of `[plugins.\"io.containerd.grpc.v1.cri\".registry]` is deprecated since containerd v1.5 and will be removed in containerd v2.0." +
+		"Use `config_path` instead.",
 }
 
 // Valid checks whether a given Warning is valid