Merge pull request #9258 from samuelkarp/introspection-deprecation-warning

Expose usage of deprecated features

api/next.pb.txt

@@ -4344,6 +4344,7 @@ file {
   dependency: "github.com/containerd/containerd/api/types/platform.proto"
   dependency: "google/rpc/status.proto"
   dependency: "google/protobuf/empty.proto"
+  dependency: "google/protobuf/timestamp.proto"
   message_type {
     name: "Plugin"
     field {
@@ -4463,6 +4464,39 @@ file {
       type: TYPE_UINT64
       json_name: "pidns"
     }
+    field {
+      name: "deprecations"
+      number: 4
+      label: LABEL_REPEATED
+      type: TYPE_MESSAGE
+      type_name: ".containerd.services.introspection.v1.DeprecationWarning"
+      json_name: "deprecations"
+    }
+  }
+  message_type {
+    name: "DeprecationWarning"
+    field {
+      name: "id"
+      number: 1
+      label: LABEL_OPTIONAL
+      type: TYPE_STRING
+      json_name: "id"
+    }
+    field {
+      name: "message"
+      number: 2
+      label: LABEL_OPTIONAL
+      type: TYPE_STRING
+      json_name: "message"
+    }
+    field {
+      name: "last_occurrence"
+      number: 3
+      label: LABEL_OPTIONAL
+      type: TYPE_MESSAGE
+      type_name: ".google.protobuf.Timestamp"
+      json_name: "lastOccurrence"
+    }
   }
   service {
     name: "Introspection"

api/services/introspection/v1/introspection.pb.go

@@ -27,6 +27,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	emptypb "google.golang.org/protobuf/types/known/emptypb"
+	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
 	reflect "reflect"
 	sync "sync"
 )
@@ -272,9 +273,10 @@ type ServerResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	UUID  string `protobuf:"bytes,1,opt,name=uuid,proto3" json:"uuid,omitempty"`
+	UUID         string                `protobuf:"bytes,1,opt,name=uuid,proto3" json:"uuid,omitempty"`
-	Pid   uint64 `protobuf:"varint,2,opt,name=pid,proto3" json:"pid,omitempty"`
+	Pid          uint64                `protobuf:"varint,2,opt,name=pid,proto3" json:"pid,omitempty"`
-	Pidns uint64 `protobuf:"varint,3,opt,name=pidns,proto3" json:"pidns,omitempty"` // PID namespace, such as 4026531836
+	Pidns        uint64                `protobuf:"varint,3,opt,name=pidns,proto3" json:"pidns,omitempty"` // PID namespace, such as 4026531836
+	Deprecations []*DeprecationWarning `protobuf:"bytes,4,rep,name=deprecations,proto3" json:"deprecations,omitempty"`
 }
 
 func (x *ServerResponse) Reset() {
@@ -330,6 +332,76 @@ func (x *ServerResponse) GetPidns() uint64 {
 	return 0
 }
 
+func (x *ServerResponse) GetDeprecations() []*DeprecationWarning {
+	if x != nil {
+		return x.Deprecations
+	}
+	return nil
+}
+
+type DeprecationWarning struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	ID             string                 `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
+	Message        string                 `protobuf:"bytes,2,opt,name=message,proto3" json:"message,omitempty"`
+	LastOccurrence *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=last_occurrence,json=lastOccurrence,proto3" json:"last_occurrence,omitempty"`
+}
+
+func (x *DeprecationWarning) Reset() {
+	*x = DeprecationWarning{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_msgTypes[4]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *DeprecationWarning) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*DeprecationWarning) ProtoMessage() {}
+
+func (x *DeprecationWarning) ProtoReflect() protoreflect.Message {
+	mi := &file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_msgTypes[4]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use DeprecationWarning.ProtoReflect.Descriptor instead.
+func (*DeprecationWarning) Descriptor() ([]byte, []int) {
+	return file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_rawDescGZIP(), []int{4}
+}
+
+func (x *DeprecationWarning) GetID() string {
+	if x != nil {
+		return x.ID
+	}
+	return ""
+}
+
+func (x *DeprecationWarning) GetMessage() string {
+	if x != nil {
+		return x.Message
+	}
+	return ""
+}
+
+func (x *DeprecationWarning) GetLastOccurrence() *timestamppb.Timestamp {
+	if x != nil {
+		return x.LastOccurrence
+	}
+	return nil
+}
+
 var File_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto protoreflect.FileDescriptor
 
 var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_rawDesc = []byte{
@@ -347,63 +419,79 @@ var file_github_com_containerd_containerd_api_services_introspection_v1_introspe
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-	0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x76, 0x31, 0x2e, 0x50, 0x6c, 0x75, 0x67,
-	0x69, 0x6e, 0x52, 0x07, 0x70, 0x6c, 0x75, 0x67, 0x69, 0x6e, 0x73, 0x22, 0x4c, 0x0a, 0x0e, 0x53,
-	0x65, 0x72, 0x76, 0x65, 0x72, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12, 0x12, 0x0a,
-	0x04, 0x75, 0x75, 0x69, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x75, 0x75, 0x69,
-	0x64, 0x12, 0x10, 0x0a, 0x03, 0x70, 0x69, 0x64, 0x18, 0x02, 0x20, 0x01, 0x28, 0x04, 0x52, 0x03,
-	0x70, 0x69, 0x64, 0x12, 0x14, 0x0a, 0x05, 0x70, 0x69, 0x64, 0x6e, 0x73, 0x18, 0x03, 0x20, 0x01,
-	0x28, 0x04, 0x52, 0x05, 0x70, 0x69, 0x64, 0x6e, 0x73, 0x32, 0xdf, 0x01, 0x0a, 0x0d, 0x49, 0x6e,
-	0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x12, 0x76, 0x0a, 0x07, 0x50,
-	0x6c, 0x75, 0x67, 0x69, 0x6e, 0x73, 0x12, 0x34, 0x2e, 0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e,
-	0x65, 0x72, 0x64, 0x2e, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x73, 0x2e, 0x69, 0x6e, 0x74,
-	0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x76, 0x31, 0x2e, 0x50, 0x6c,
-	0x75, 0x67, 0x69, 0x6e, 0x73, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a, 0x35, 0x2e, 0x63,
 	0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65, 0x72, 0x64, 0x2e, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63,
 	0x65, 0x73, 0x2e, 0x69, 0x6e, 0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e,
-	0x2e, 0x76, 0x31, 0x2e, 0x50, 0x6c, 0x75, 0x67, 0x69, 0x6e, 0x73, 0x52, 0x65, 0x73, 0x70, 0x6f,
+	0x2e, 0x76, 0x31, 0x2e, 0x50, 0x6c, 0x75, 0x67, 0x69, 0x6e, 0x73, 0x52, 0x65, 0x71, 0x75, 0x65,
-	0x6e, 0x73, 0x65, 0x12, 0x56, 0x0a, 0x06, 0x53, 0x65, 0x72, 0x76, 0x65, 0x72, 0x12, 0x16, 0x2e,
+	0x73, 0x74, 0x1a, 0x35, 0x2e, 0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65, 0x72, 0x64, 0x2e,
-	0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e,
+	0x73, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x73, 0x2e, 0x69, 0x6e, 0x74, 0x72, 0x6f, 0x73, 0x70,
-	0x45, 0x6d, 0x70, 0x74, 0x79, 0x1a, 0x34, 0x2e, 0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65,
+	0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x76, 0x31, 0x2e, 0x50, 0x6c, 0x75, 0x67, 0x69, 0x6e,
-	0x72, 0x64, 0x2e, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x73, 0x2e, 0x69, 0x6e, 0x74, 0x72,
+	0x73, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12, 0x56, 0x0a, 0x06, 0x53, 0x65, 0x72,
-	0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x76, 0x31, 0x2e, 0x53, 0x65, 0x72,
+	0x76, 0x65, 0x72, 0x12, 0x16, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f,
-	0x76, 0x65, 0x72, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x42, 0x4e, 0x5a, 0x4c, 0x67,
+	0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x45, 0x6d, 0x70, 0x74, 0x79, 0x1a, 0x34, 0x2e, 0x63, 0x6f,
-	0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69,
+	0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65, 0x72, 0x64, 0x2e, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65,
-	0x6e, 0x65, 0x72, 0x64, 0x2f, 0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65, 0x72, 0x64, 0x2f,
+	0x73, 0x2e, 0x69, 0x6e, 0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e,
-	0x61, 0x70, 0x69, 0x2f, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x73, 0x2f, 0x69, 0x6e, 0x74,
+	0x76, 0x31, 0x2e, 0x53, 0x65, 0x72, 0x76, 0x65, 0x72, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73,
-	0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2f, 0x76, 0x31, 0x3b, 0x69, 0x6e,
+	0x65, 0x42, 0x4e, 0x5a, 0x4c, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f,
-	0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x62, 0x06, 0x70, 0x72, 0x6f,
+	0x63, 0x6f, 0x6e, 0x74, 0x61, 0x69, 0x6e, 0x65, 0x72, 0x64, 0x2f, 0x63, 0x6f, 0x6e, 0x74, 0x61,
-	0x74, 0x6f, 0x33,
+	0x69, 0x6e, 0x65, 0x72, 0x64, 0x2f, 0x61, 0x70, 0x69, 0x2f, 0x73, 0x65, 0x72, 0x76, 0x69, 0x63,
+	0x65, 0x73, 0x2f, 0x69, 0x6e, 0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e,
+	0x2f, 0x76, 0x31, 0x3b, 0x69, 0x6e, 0x74, 0x72, 0x6f, 0x73, 0x70, 0x65, 0x63, 0x74, 0x69, 0x6f,
+	0x6e, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -418,31 +506,35 @@ func file_github_com_containerd_containerd_api_services_introspection_v1_introsp
 	return file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_rawDescData
 }
 
-var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
+var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_msgTypes = make([]protoimpl.MessageInfo, 6)
 var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_goTypes = []interface{}{
-	(*Plugin)(nil),          // 0: containerd.services.introspection.v1.Plugin
+	(*Plugin)(nil),                // 0: containerd.services.introspection.v1.Plugin
-	(*PluginsRequest)(nil),  // 1: containerd.services.introspection.v1.PluginsRequest
+	(*PluginsRequest)(nil),        // 1: containerd.services.introspection.v1.PluginsRequest
-	(*PluginsResponse)(nil), // 2: containerd.services.introspection.v1.PluginsResponse
+	(*PluginsResponse)(nil),       // 2: containerd.services.introspection.v1.PluginsResponse
-	(*ServerResponse)(nil),  // 3: containerd.services.introspection.v1.ServerResponse
+	(*ServerResponse)(nil),        // 3: containerd.services.introspection.v1.ServerResponse
-	nil,                     // 4: containerd.services.introspection.v1.Plugin.ExportsEntry
+	(*DeprecationWarning)(nil),    // 4: containerd.services.introspection.v1.DeprecationWarning
-	(*types.Platform)(nil),  // 5: containerd.types.Platform
+	nil,                           // 5: containerd.services.introspection.v1.Plugin.ExportsEntry
-	(*status.Status)(nil),   // 6: google.rpc.Status
+	(*types.Platform)(nil),        // 6: containerd.types.Platform
-	(*emptypb.Empty)(nil),   // 7: google.protobuf.Empty
+	(*status.Status)(nil),         // 7: google.rpc.Status
+	(*timestamppb.Timestamp)(nil), // 8: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),         // 9: google.protobuf.Empty
 }
 var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_depIdxs = []int32{
-	5, // 0: containerd.services.introspection.v1.Plugin.platforms:type_name -> containerd.types.Platform
+	6, // 0: containerd.services.introspection.v1.Plugin.platforms:type_name -> containerd.types.Platform
-	4, // 1: containerd.services.introspection.v1.Plugin.exports:type_name -> containerd.services.introspection.v1.Plugin.ExportsEntry
+	5, // 1: containerd.services.introspection.v1.Plugin.exports:type_name -> containerd.services.introspection.v1.Plugin.ExportsEntry
-	6, // 2: containerd.services.introspection.v1.Plugin.init_err:type_name -> google.rpc.Status
+	7, // 2: containerd.services.introspection.v1.Plugin.init_err:type_name -> google.rpc.Status
 	0, // 3: containerd.services.introspection.v1.PluginsResponse.plugins:type_name -> containerd.services.introspection.v1.Plugin
-	1, // 4: containerd.services.introspection.v1.Introspection.Plugins:input_type -> containerd.services.introspection.v1.PluginsRequest
+	4, // 4: containerd.services.introspection.v1.ServerResponse.deprecations:type_name -> containerd.services.introspection.v1.DeprecationWarning
-	7, // 5: containerd.services.introspection.v1.Introspection.Server:input_type -> google.protobuf.Empty
+	8, // 5: containerd.services.introspection.v1.DeprecationWarning.last_occurrence:type_name -> google.protobuf.Timestamp
-	2, // 6: containerd.services.introspection.v1.Introspection.Plugins:output_type -> containerd.services.introspection.v1.PluginsResponse
+	1, // 6: containerd.services.introspection.v1.Introspection.Plugins:input_type -> containerd.services.introspection.v1.PluginsRequest
-	3, // 7: containerd.services.introspection.v1.Introspection.Server:output_type -> containerd.services.introspection.v1.ServerResponse
+	9, // 7: containerd.services.introspection.v1.Introspection.Server:input_type -> google.protobuf.Empty
-	6, // [6:8] is the sub-list for method output_type
+	2, // 8: containerd.services.introspection.v1.Introspection.Plugins:output_type -> containerd.services.introspection.v1.PluginsResponse
-	4, // [4:6] is the sub-list for method input_type
+	3, // 9: containerd.services.introspection.v1.Introspection.Server:output_type -> containerd.services.introspection.v1.ServerResponse
-	4, // [4:4] is the sub-list for extension type_name
+	8, // [8:10] is the sub-list for method output_type
-	4, // [4:4] is the sub-list for extension extendee
+	6, // [6:8] is the sub-list for method input_type
-	0, // [0:4] is the sub-list for field type_name
+	6, // [6:6] is the sub-list for extension type_name
+	6, // [6:6] is the sub-list for extension extendee
+	0, // [0:6] is the sub-list for field type_name
 }
 
 func init() {
@@ -501,6 +593,18 @@ func file_github_com_containerd_containerd_api_services_introspection_v1_introsp
 				return nil
 			}
 		}
+		file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*DeprecationWarning); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
 	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
@@ -508,7 +612,7 @@ func file_github_com_containerd_containerd_api_services_introspection_v1_introsp
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   5,
+			NumMessages:   6,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

api/services/introspection/v1/introspection.proto

@@ -21,6 +21,7 @@ package containerd.services.introspection.v1;
 import "github.com/containerd/containerd/api/types/platform.proto";
 import "google/rpc/status.proto";
 import "google/protobuf/empty.proto";
+import "google/protobuf/timestamp.proto";
 
 option go_package = "github.com/containerd/containerd/api/services/introspection/v1;introspection";
 
@@ -102,4 +103,11 @@ message ServerResponse {
 	string uuid = 1;
 	uint64 pid = 2;
 	uint64 pidns = 3; // PID namespace, such as 4026531836
+	repeated DeprecationWarning deprecations = 4;
+}
+
+message DeprecationWarning {
+	string id = 1;
+	string message = 2;
+	google.protobuf.Timestamp last_occurrence = 3;
 }

cmd/containerd/builtins/builtins.go

@@ -46,4 +46,5 @@ import (
 	_ "github.com/containerd/containerd/services/tasks"
 	_ "github.com/containerd/containerd/services/transfer"
 	_ "github.com/containerd/containerd/services/version"
+	_ "github.com/containerd/containerd/services/warning"
 )

cmd/ctr/app/main.go

@@ -20,8 +20,13 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/containerd/log"
+	"github.com/urfave/cli"
+	"google.golang.org/grpc/grpclog"
+
 	"github.com/containerd/containerd/cmd/ctr/commands/containers"
 	"github.com/containerd/containerd/cmd/ctr/commands/content"
+	"github.com/containerd/containerd/cmd/ctr/commands/deprecations"
 	"github.com/containerd/containerd/cmd/ctr/commands/events"
 	"github.com/containerd/containerd/cmd/ctr/commands/images"
 	"github.com/containerd/containerd/cmd/ctr/commands/info"
@@ -39,9 +44,6 @@ import (
 	"github.com/containerd/containerd/defaults"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/version"
-	"github.com/containerd/log"
-	"github.com/urfave/cli"
-	"google.golang.org/grpc/grpclog"
 )
 
 var extraCmds = []cli.Command{}
@@ -118,6 +120,7 @@ containerd CLI
 		ociCmd.Command,
 		sandboxes.Command,
 		info.Command,
+		deprecations.Command,
 	}, extraCmds...)
 	app.Before = func(context *cli.Context) error {
 		if context.GlobalBool("debug") {

cmd/ctr/commands/deprecations/deprecations.go

@@ -0,0 +1,113 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package deprecations
+
+import (
+	"fmt"
+	"os"
+	"text/tabwriter"
+	"time"
+
+	"github.com/urfave/cli"
+
+	api "github.com/containerd/containerd/api/services/introspection/v1"
+	"github.com/containerd/containerd/cmd/ctr/commands"
+	"github.com/containerd/containerd/protobuf"
+	ptypes "github.com/containerd/containerd/protobuf/types"
+)
+
+// Command is the parent for all commands under "deprecations"
+var Command = cli.Command{
+	Name: "deprecations",
+	Subcommands: []cli.Command{
+		listCommand,
+	},
+}
+var listCommand = cli.Command{
+	Name:  "list",
+	Usage: "Print warnings for deprecations",
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "format",
+			Usage: "output format to use (Examples: 'default', 'json')",
+		},
+	},
+	Action: func(context *cli.Context) error {
+		client, ctx, cancel, err := commands.NewClient(context)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+
+		resp, err := client.IntrospectionService().Server(ctx, &ptypes.Empty{})
+		if err != nil {
+			return err
+		}
+		wrn := warnings(resp)
+		if len(wrn) > 0 {
+			switch context.String("format") {
+			case "json":
+				commands.PrintAsJSON(warnings(resp))
+				return nil
+			default:
+				w := tabwriter.NewWriter(os.Stdout, 4, 8, 4, ' ', 0)
+				fmt.Fprintln(w, "ID\tLAST OCCURRENCE\tMESSAGE\t")
+				for _, dw := range wrn {
+					if _, err := fmt.Fprintf(w, "%s\t%s\t%s\n",
+						dw.ID,
+						dw.LastOccurrence.Format(time.RFC3339Nano),
+						dw.Message,
+					); err != nil {
+						return err
+					}
+				}
+				return w.Flush()
+			}
+
+		}
+		return nil
+	},
+}
+
+type deprecationWarning struct {
+	ID             string    `json:"id"`
+	Message        string    `json:"message"`
+	LastOccurrence time.Time `json:"lastOccurrence"`
+}
+
+func warnings(in *api.ServerResponse) []deprecationWarning {
+	var warnings []deprecationWarning
+	for _, dw := range in.Deprecations {
+		wrn := deprecationWarningFromPB(dw)
+		if wrn == nil {
+			continue
+		}
+		warnings = append(warnings, *wrn)
+	}
+	return warnings
+}
+func deprecationWarningFromPB(in *api.DeprecationWarning) *deprecationWarning {
+	if in == nil {
+		return nil
+	}
+	lo := protobuf.FromTimestamp(in.LastOccurrence)
+	return &deprecationWarning{
+		ID:             in.ID,
+		Message:        in.Message,
+		LastOccurrence: lo,
+	}
+}

images/labels.go

@@ -0,0 +1,21 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package images
+
+const (
+	ConvertedDockerSchema1LabelKey = "io.containerd.image/converted-docker-schema1"
+)

pkg/deprecation/deprecation.go

@@ -0,0 +1,46 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package deprecation
+
+type Warning string
+
+const (
+	// Prefix is a standard prefix for all Warnings, used for filtering plugin Exports
+	Prefix = "io.containerd.deprecation/"
+	// PullSchema1Image is a warning for the use of schema 1 images
+	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"
+)
+
+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.",
+}
+
+// Valid checks whether a given Warning is valid
+func Valid(id Warning) bool {
+	_, ok := messages[id]
+	return ok
+}
+
+// Message returns the human-readable message for a given Warning
+func Message(id Warning) (string, bool) {
+	msg, ok := messages[id]
+	return msg, ok
+}

plugin/context.go

@@ -127,6 +127,19 @@ func (ps *Set) Get(t Type) (interface{}, error) {
 	return nil, fmt.Errorf("no plugins registered for %s: %w", t, ErrPluginNotFound)
 }
 
+// GetByID returns the plugin of the given type and ID
+func (ps *Set) GetByID(t Type, id string) (*Plugin, error) {
+	typSet, ok := ps.byTypeAndID[t]
+	if !ok || len(typSet) == 0 {
+		return nil, fmt.Errorf("no plugins registered for %s: %w", t, ErrPluginNotFound)
+	}
+	p, ok := typSet[id]
+	if !ok {
+		return nil, fmt.Errorf("no plugins registered for %s %q: %w", t, id, ErrPluginNotFound)
+	}
+	return p, nil
+}
+
 // GetAll returns all initialized plugins
 func (ps *Set) GetAll() []*Plugin {
 	return ps.ordered

plugin/dynamic/dynamic.go

@@ -23,7 +23,7 @@ import "fmt"
 // Load is currently only implemented on non-static, non-gccgo builds for amd64
 // and arm64, and plugins must be built with the exact same version of Go as
 // containerd itself.
-func Load(path string) (err error) {
+func Load(path string) (loaded int, err error) {
 	defer func() {
 		if v := recover(); v != nil {
 			rerr, ok := v.(error)

plugin/dynamic/dynamic_supported.go

@@ -25,12 +25,13 @@ import (
 	"runtime"
 )
 
-// loadPlugins loads all plugins for the OS and Arch
+// loadPlugins loads all plugins for the OS and Arch that containerd is built
-// that containerd is built for inside the provided path
+// for inside the provided path and returns the count of successfully-loaded
-func loadPlugins(path string) error {
+// plugins
+func loadPlugins(path string) (int, error) {
 	abs, err := filepath.Abs(path)
 	if err != nil {
-		return err
+		return 0, err
 	}
 	pattern := filepath.Join(abs, fmt.Sprintf(
 		"*-%s-%s.%s",
@@ -40,14 +41,16 @@ func loadPlugins(path string) error {
 	))
 	libs, err := filepath.Glob(pattern)
 	if err != nil {
-		return err
+		return 0, err
 	}
+	loaded := 0
 	for _, lib := range libs {
 		if _, err := plugin.Open(lib); err != nil {
-			return err
+			return loaded, err
 		}
+		loaded++
 	}
-	return nil
+	return loaded, nil
 }
 
 // getLibExt returns a platform specific lib extension for

plugin/dynamic/dynamic_unsupported.go

@@ -23,6 +23,6 @@ package dynamic
 // - with gccgo: gccgo has no plugin support golang/go#36403
 // - on static builds; https://github.com/containerd/containerd/commit/0d682e24a1ba8e93e5e54a73d64f7d256f87492f
 // - on architectures other than amd64 and arm64 (other architectures need to be tested)
-func loadPlugins(path string) error {
+func loadPlugins(path string) (int, error) {
-	return nil
+	return 0, nil
 }

plugins/types.go

@@ -65,11 +65,15 @@ const (
 	SandboxControllerPlugin plugin.Type = "io.containerd.sandbox.controller.v1"
 	// ImageVerifierPlugin implements an image verifier service
 	ImageVerifierPlugin plugin.Type = "io.containerd.image-verifier.v1"
+	// WarningPlugin implements a warning service
+	WarningPlugin plugin.Type = "io.containerd.warning.v1"
 )
 
 const (
 	// RuntimeRuncV2 is the runc runtime that supports multiple containers per shim
 	RuntimeRuncV2 = "io.containerd.runc.v2"
+
+	DeprecationsPlugin = "deprecations"
 )
 
 const (

pull.go

@@ -21,6 +21,9 @@ import (
 	"errors"
 	"fmt"
 
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/sync/semaphore"
+
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/pkg/unpack"
@@ -29,13 +32,10 @@ import (
 	"github.com/containerd/containerd/remotes/docker"
 	"github.com/containerd/containerd/remotes/docker/schema1" //nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
 	"github.com/containerd/containerd/tracing"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"golang.org/x/sync/semaphore"
 )
 
 const (
-	pullSpanPrefix                 = "pull"
+	pullSpanPrefix = "pull"
-	convertedDockerSchema1LabelKey = "io.containerd.image/converted-docker-schema1"
 )
 
 // Pull downloads the provided content into containerd's content store
@@ -278,7 +278,7 @@ func (c *Client) fetch(ctx context.Context, rCtx *RemoteContext, ref string, lim
 		if rCtx.Labels == nil {
 			rCtx.Labels = make(map[string]string)
 		}
-		rCtx.Labels[convertedDockerSchema1LabelKey] = originalSchema1Digest
+		rCtx.Labels[images.ConvertedDockerSchema1LabelKey] = originalSchema1Digest
 	}
 
 	return images.Image{

services/images/local.go

@@ -19,6 +19,11 @@ package images
 import (
 	"context"
 
+	"github.com/containerd/log"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
 	eventstypes "github.com/containerd/containerd/api/events"
 	imagesapi "github.com/containerd/containerd/api/services/images/v1"
 	"github.com/containerd/containerd/errdefs"
@@ -26,16 +31,14 @@ import (
 	"github.com/containerd/containerd/gc"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/pkg/deprecation"
 	"github.com/containerd/containerd/pkg/epoch"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/plugin/registry"
 	"github.com/containerd/containerd/plugins"
 	ptypes "github.com/containerd/containerd/protobuf/types"
 	"github.com/containerd/containerd/services"
-	"github.com/containerd/log"
+	"github.com/containerd/containerd/services/warning"
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 func init() {
@@ -46,6 +49,7 @@ func init() {
 			plugins.EventPlugin,
 			plugins.MetadataPlugin,
 			plugins.GCPlugin,
+			plugins.WarningPlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
 			m, err := ic.Get(plugins.MetadataPlugin)
@@ -56,16 +60,20 @@ func init() {
 			if err != nil {
 				return nil, err
 			}
-
 			ep, err := ic.Get(plugins.EventPlugin)
 			if err != nil {
 				return nil, err
 			}
+			w, err := ic.Get(plugins.WarningPlugin)
+			if err != nil {
+				return nil, err
+			}
 
 			return &local{
 				store:     metadata.NewImageStore(m.(*metadata.DB)),
 				publisher: ep.(events.Publisher),
 				gc:        g.(gcScheduler),
+				warnings:  w.(warning.Service),
 			}, nil
 		},
 	})
@@ -79,6 +87,7 @@ type local struct {
 	store     images.Store
 	gc        gcScheduler
 	publisher events.Publisher
+	warnings  warning.Service
 }
 
 var _ imagesapi.ImagesClient = &local{}
@@ -134,6 +143,7 @@ func (l *local) Create(ctx context.Context, req *imagesapi.CreateImageRequest, _
 		return nil, err
 	}
 
+	l.emitSchema1DeprecationWarning(ctx, &image)
 	return &resp, nil
 
 }
@@ -172,6 +182,7 @@ func (l *local) Update(ctx context.Context, req *imagesapi.UpdateImageRequest, _
 		return nil, err
 	}
 
+	l.emitSchema1DeprecationWarning(ctx, &image)
 	return &resp, nil
 }
 
@@ -203,3 +214,15 @@ func (l *local) Delete(ctx context.Context, req *imagesapi.DeleteImageRequest, _
 
 	return &ptypes.Empty{}, nil
 }
+
+func (l *local) emitSchema1DeprecationWarning(ctx context.Context, image *images.Image) {
+	if image == nil {
+		return
+	}
+	dgst, ok := image.Labels[images.ConvertedDockerSchema1LabelKey]
+	if !ok {
+		return
+	}
+	log.G(ctx).WithField("name", image.Name).WithField("schema1digest", dgst).Warn("conversion from schema 1 images is deprecated")
+	l.warnings.Emit(ctx, deprecation.PullSchema1Image)
+}

services/introspection/local.go

@@ -18,11 +18,18 @@ package introspection
 
 import (
 	context "context"
+	"errors"
 	"os"
 	"path/filepath"
 	"runtime"
 	"sync"
 
+	"github.com/google/uuid"
+	"google.golang.org/genproto/googleapis/rpc/code"
+	rpc "google.golang.org/genproto/googleapis/rpc/status"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/status"
+
 	api "github.com/containerd/containerd/api/services/introspection/v1"
 	"github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/errdefs"
@@ -30,25 +37,42 @@ import (
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/plugin/registry"
 	"github.com/containerd/containerd/plugins"
+	"github.com/containerd/containerd/protobuf"
 	ptypes "github.com/containerd/containerd/protobuf/types"
 	"github.com/containerd/containerd/services"
-	"github.com/google/uuid"
+	"github.com/containerd/containerd/services/warning"
-	"google.golang.org/genproto/googleapis/rpc/code"
-	rpc "google.golang.org/genproto/googleapis/rpc/status"
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/status"
 )
 
 func init() {
 	registry.Register(&plugin.Registration{
 		Type:     plugins.ServicePlugin,
 		ID:       services.IntrospectionService,
-		Requires: []plugin.Type{},
+		Requires: []plugin.Type{plugins.WarningPlugin},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			sps, err := ic.GetByType(plugins.WarningPlugin)
+			if err != nil {
+				return nil, err
+			}
+			p, ok := sps[plugins.DeprecationsPlugin]
+			if !ok {
+				return nil, errors.New("warning service not found")
+			}
+
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+
+			warningClient, ok := i.(warning.Service)
+			if !ok {
+				return nil, errors.New("could not create a local client for warning service")
+			}
+
 			// this service fetches all plugins through the plugin set of the plugin context
 			return &Local{
-				plugins: ic.Plugins(),
+				plugins:       ic.Plugins(),
-				root:    ic.Properties[plugins.PropertyRootDir],
+				root:          ic.Properties[plugins.PropertyRootDir],
+				warningClient: warningClient,
 			}, nil
 		},
 	})
@@ -56,10 +80,11 @@ func init() {
 
 // Local is a local implementation of the introspection service
 type Local struct {
-	mu          sync.Mutex
+	mu            sync.Mutex
-	root        string
+	root          string
-	plugins     *plugin.Set
+	plugins       *plugin.Set
-	pluginCache []*api.Plugin
+	pluginCache   []*api.Plugin
+	warningClient warning.Service
 }
 
 var _ = (api.IntrospectionClient)(&Local{})
@@ -117,9 +142,10 @@ func (l *Local) Server(ctx context.Context, _ *ptypes.Empty, _ ...grpc.CallOptio
 		}
 	}
 	return &api.ServerResponse{
-		UUID:  u,
+		UUID:         u,
-		Pid:   uint64(pid),
+		Pid:          uint64(pid),
-		Pidns: pidns,
+		Pidns:        pidns,
+		Deprecations: l.getWarnings(ctx),
 	}, nil
 }
 
@@ -161,6 +187,10 @@ func (l *Local) uuidPath() string {
 	return filepath.Join(l.root, "uuid")
 }
 
+func (l *Local) getWarnings(ctx context.Context) []*api.DeprecationWarning {
+	return warningsPB(ctx, l.warningClient.Warnings())
+}
+
 func adaptPlugin(o interface{}) filters.Adaptor {
 	obj := o.(*api.Plugin)
 	return filters.AdapterFunc(func(fieldpath []string) (string, bool) {
@@ -233,3 +263,16 @@ func pluginsToPB(plugins []*plugin.Plugin) []*api.Plugin {
 
 	return pluginsPB
 }
+
+func warningsPB(ctx context.Context, warnings []warning.Warning) []*api.DeprecationWarning {
+	var pb []*api.DeprecationWarning
+
+	for _, w := range warnings {
+		pb = append(pb, &api.DeprecationWarning{
+			ID:             string(w.ID),
+			Message:        w.Message,
+			LastOccurrence: protobuf.ToTimestamp(w.LastOccurrence),
+		})
+	}
+	return pb
+}

services/server/server.go

@@ -34,26 +34,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	csapi "github.com/containerd/containerd/api/services/content/v1"
-	diffapi "github.com/containerd/containerd/api/services/diff/v1"
-	sbapi "github.com/containerd/containerd/api/services/sandbox/v1"
-	ssapi "github.com/containerd/containerd/api/services/snapshots/v1"
-	"github.com/containerd/containerd/content/local"
-	csproxy "github.com/containerd/containerd/content/proxy"
-	"github.com/containerd/containerd/defaults"
-	"github.com/containerd/containerd/diff"
-	diffproxy "github.com/containerd/containerd/diff/proxy"
-	"github.com/containerd/containerd/pkg/dialer"
-	"github.com/containerd/containerd/pkg/timeout"
-	"github.com/containerd/containerd/platforms"
-	"github.com/containerd/containerd/plugin"
-	"github.com/containerd/containerd/plugin/dynamic"
-	"github.com/containerd/containerd/plugin/registry"
-	"github.com/containerd/containerd/plugins"
-	sbproxy "github.com/containerd/containerd/sandbox/proxy"
-	srvconfig "github.com/containerd/containerd/services/server/config"
-	ssproxy "github.com/containerd/containerd/snapshots/proxy"
-	"github.com/containerd/containerd/sys"
 	"github.com/containerd/log"
 	"github.com/containerd/ttrpc"
 	"github.com/docker/go-metrics"
@@ -65,6 +45,29 @@ import (
 	"google.golang.org/grpc/backoff"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+
+	csapi "github.com/containerd/containerd/api/services/content/v1"
+	diffapi "github.com/containerd/containerd/api/services/diff/v1"
+	sbapi "github.com/containerd/containerd/api/services/sandbox/v1"
+	ssapi "github.com/containerd/containerd/api/services/snapshots/v1"
+	"github.com/containerd/containerd/content/local"
+	csproxy "github.com/containerd/containerd/content/proxy"
+	"github.com/containerd/containerd/defaults"
+	"github.com/containerd/containerd/diff"
+	diffproxy "github.com/containerd/containerd/diff/proxy"
+	"github.com/containerd/containerd/pkg/deprecation"
+	"github.com/containerd/containerd/pkg/dialer"
+	"github.com/containerd/containerd/pkg/timeout"
+	"github.com/containerd/containerd/platforms"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/plugin/dynamic"
+	"github.com/containerd/containerd/plugin/registry"
+	"github.com/containerd/containerd/plugins"
+	sbproxy "github.com/containerd/containerd/sandbox/proxy"
+	srvconfig "github.com/containerd/containerd/services/server/config"
+	"github.com/containerd/containerd/services/warning"
+	ssproxy "github.com/containerd/containerd/snapshots/proxy"
+	"github.com/containerd/containerd/sys"
 )
 
 // CreateTopLevelDirectories creates the top-level root and state directories.
@@ -330,9 +333,35 @@ func New(ctx context.Context, config *srvconfig.Config) (*Server, error) {
 			return nil, err
 		}
 	}
+
+	recordConfigDeprecations(ctx, config, initialized)
 	return s, nil
 }
 
+// recordConfigDeprecations attempts to record use of any deprecated config field.  Failures are logged and ignored.
+func recordConfigDeprecations(ctx context.Context, config *srvconfig.Config, set *plugin.Set) {
+	// record any detected deprecations without blocking server startup
+	plugin, err := set.GetByID(plugins.WarningPlugin, plugins.DeprecationsPlugin)
+	if err != nil {
+		log.G(ctx).WithError(err).Warn("failed to load warning service to record deprecations")
+		return
+	}
+	instance, err := plugin.Instance()
+	if err != nil {
+		log.G(ctx).WithError(err).Warn("failed to load warning service to record deprecations")
+		return
+	}
+	warn, ok := instance.(warning.Service)
+	if !ok {
+		log.G(ctx).WithError(err).Warn("failed to load warning service to record deprecations, unexpected plugin type")
+		return
+	}
+
+	if config.PluginDir != "" { //nolint:staticcheck
+		warn.Emit(ctx, deprecation.GoPluginLibrary)
+	}
+}
+
 // Server is the containerd main daemon
 type Server struct {
 	grpcServer  *grpc.Server
@@ -433,13 +462,15 @@ func (s *Server) Wait() {
 // of all plugins.
 func LoadPlugins(ctx context.Context, config *srvconfig.Config) ([]plugin.Registration, error) {
 	// load all plugins into containerd
-	path := config.PluginDir //nolint: staticcheck
+	path := config.PluginDir //nolint:staticcheck
 	if path == "" {
 		path = filepath.Join(config.Root, "plugins")
 	}
-	log.G(ctx).Warning("`go_plugin` is deprecated, please use `external plugins` instead")
+	if count, err := dynamic.Load(path); err != nil {
-	if err := dynamic.Load(path); err != nil {
 		return nil, err
+	} else if count > 0 || config.PluginDir != "" { //nolint:staticcheck
+		config.PluginDir = path //nolint:staticcheck
+		log.G(ctx).Warningf("loaded %d dynamic plugins. `go_plugin` is deprecated, please use `external plugins` instead", count)
 	}
 	// load additional plugins that don't automatically register themselves
 	registry.Register(&plugin.Registration{

services/warning/service.go

@@ -0,0 +1,85 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package warning
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/containerd/log"
+
+	deprecation "github.com/containerd/containerd/pkg/deprecation"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/plugin/registry"
+	"github.com/containerd/containerd/plugins"
+)
+
+type Service interface {
+	Emit(context.Context, deprecation.Warning)
+	Warnings() []Warning
+}
+
+func init() {
+	registry.Register(&plugin.Registration{
+		Type: plugins.WarningPlugin,
+		ID:   plugins.DeprecationsPlugin,
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			return &service{warnings: make(map[deprecation.Warning]time.Time)}, nil
+		},
+	})
+}
+
+type Warning struct {
+	ID             deprecation.Warning
+	LastOccurrence time.Time
+	Message        string
+}
+
+var _ Service = (*service)(nil)
+
+type service struct {
+	warnings map[deprecation.Warning]time.Time
+	m        sync.RWMutex
+}
+
+func (s *service) Emit(ctx context.Context, warning deprecation.Warning) {
+	if !deprecation.Valid(warning) {
+		log.G(ctx).WithField("warningID", string(warning)).Warn("invalid deprecation warning")
+		return
+	}
+	s.m.Lock()
+	defer s.m.Unlock()
+	s.warnings[warning] = time.Now()
+}
+func (s *service) Warnings() []Warning {
+	s.m.RLock()
+	defer s.m.RUnlock()
+	var warnings []Warning
+	for k, v := range s.warnings {
+		msg, ok := deprecation.Message(k)
+		if !ok {
+			continue
+		}
+		warnings = append(warnings, Warning{
+			ID:             k,
+			LastOccurrence: v,
+			Message:        msg,
+		})
+	}
+	return warnings
+}