clientv3: embed api version in metadata

ref.
#11687

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>

clientv3/client.go

@@ -37,7 +37,6 @@ import (
 	"google.golang.org/grpc/codes"
 	grpccredentials "google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
-	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
 
@@ -393,13 +392,6 @@ func (c *Client) dialWithBalancerCreds(ep string) grpccredentials.TransportCrede
 	return creds
 }
 
-// WithRequireLeader requires client requests to only succeed
-// when the cluster has a leader.
-func WithRequireLeader(ctx context.Context) context.Context {
-	md := metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
-	return metadata.NewOutgoingContext(ctx, md)
-}
-
 func newClient(cfg *Config) (*Client, error) {
 	if cfg == nil {
 		cfg = &Config{}

clientv3/ctx.go

@@ -0,0 +1,62 @@
+// Copyright 2020 The etcd 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 clientv3
+
+import (
+	"context"
+	"strings"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	"github.com/coreos/etcd/version"
+	"google.golang.org/grpc/metadata"
+)
+
+// WithRequireLeader requires client requests to only succeed
+// when the cluster has a leader.
+func WithRequireLeader(ctx context.Context) context.Context {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok { // no outgoing metadata ctx key, create one
+		md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+		return metadata.NewOutgoingContext(ctx, md)
+	}
+	// overwrite/add 'hasleader' key/value
+	metadataSet(md, rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+	return metadata.NewOutgoingContext(ctx, md)
+}
+
+// embeds client version
+func withVersion(ctx context.Context) context.Context {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok { // no outgoing metadata ctx key, create one
+		md = metadata.Pairs(rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
+		return metadata.NewOutgoingContext(ctx, md)
+	}
+	// overwrite/add version key/value
+	metadataSet(md, rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
+	return metadata.NewOutgoingContext(ctx, md)
+}
+
+func metadataGet(md metadata.MD, k string) []string {
+	k = strings.ToLower(k)
+	return md[k]
+}
+
+func metadataSet(md metadata.MD, k string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	k = strings.ToLower(k)
+	md[k] = vals
+}

clientv3/ctx_test.go

@@ -0,0 +1,67 @@
+// Copyright 2020 The etcd 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 clientv3
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	"github.com/coreos/etcd/version"
+	"google.golang.org/grpc/metadata"
+)
+
+func TestMetadataWithRequireLeader(t *testing.T) {
+	ctx := context.TODO()
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if ok {
+		t.Fatal("expected no outgoing metadata ctx key")
+	}
+
+	// add a conflicting key with some other value
+	md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, "invalid")
+	// add a key, and expect not be overwritten
+	metadataSet(md, "hello", "1", "2")
+	ctx = metadata.NewOutgoingContext(ctx, md)
+
+	// expect overwrites but still keep other keys
+	ctx = WithRequireLeader(ctx)
+	md, ok = metadata.FromOutgoingContext(ctx)
+	if !ok {
+		t.Fatal("expected outgoing metadata ctx key")
+	}
+	if ss := metadataGet(md, rpctypes.MetadataRequireLeaderKey); !reflect.DeepEqual(ss, []string{rpctypes.MetadataHasLeader}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataRequireLeaderKey, ss)
+	}
+	if ss := metadataGet(md, "hello"); !reflect.DeepEqual(ss, []string{"1", "2"}) {
+		t.Fatalf("unexpected metadata for 'hello' %v", ss)
+	}
+}
+
+func TestMetadataWithClientAPIVersion(t *testing.T) {
+	ctx := withVersion(WithRequireLeader(context.TODO()))
+
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		t.Fatal("expected outgoing metadata ctx key")
+	}
+	if ss := metadataGet(md, rpctypes.MetadataRequireLeaderKey); !reflect.DeepEqual(ss, []string{rpctypes.MetadataHasLeader}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataRequireLeaderKey, ss)
+	}
+	if ss := metadataGet(md, rpctypes.MetadataClientAPIVersionKey); !reflect.DeepEqual(ss, []string{version.APIVersion}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataClientAPIVersionKey, ss)
+	}
+}

clientv3/retry_interceptor.go

@@ -38,6 +38,7 @@ import (
 func (c *Client) unaryClientInterceptor(logger *zap.Logger, optFuncs ...retryOption) grpc.UnaryClientInterceptor {
 	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
 	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+		ctx = withVersion(ctx)
 		grpcOpts, retryOpts := filterCallOptions(opts)
 		callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
 		// short circuit for simplicity, and avoiding allocations.
@@ -103,6 +104,7 @@ func (c *Client) unaryClientInterceptor(logger *zap.Logger, optFuncs ...retryOpt
 func (c *Client) streamClientInterceptor(logger *zap.Logger, optFuncs ...retryOption) grpc.StreamClientInterceptor {
 	intOpts := reuseOrNewWithCallOptions(defaultOptions, optFuncs)
 	return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+		ctx = withVersion(ctx)
 		grpcOpts, retryOpts := filterCallOptions(opts)
 		callOpts := reuseOrNewWithCallOptions(intOpts, retryOpts)
 		// short circuit for simplicity, and avoiding allocations.