Merge pull request #101 from unistack-org/metadata

support response metadata

.github/workflows/build.yml

@@ -34,7 +34,7 @@ jobs:
       - name: checkout
         uses: actions/checkout@v3
       - name: lint
-        uses: golangci/golangci-lint-action@v3.2.0
+        uses: golangci/golangci-lint-action@v3.3.1
         continue-on-error: true
         with:
           # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.

.github/workflows/dependabot-automerge.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - name: metadata
         id: metadata
-        uses: dependabot/fetch-metadata@v1.3.1
+        uses: dependabot/fetch-metadata@v1.3.5
         with:
           github-token: "${{ secrets.TOKEN }}"
       - name: merge

.github/workflows/pr.yml

@@ -34,7 +34,7 @@ jobs:
       - name: checkout
         uses: actions/checkout@v3
       - name: lint
-        uses: golangci/golangci-lint-action@v3.2.0
+        uses: golangci/golangci-lint-action@v3.3.1
         continue-on-error: true
         with:
           # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.

go.mod

@@ -3,10 +3,9 @@ module go.unistack.org/micro-client-grpc/v3
 go 1.16
 
 require (
-	github.com/google/gnostic v0.6.9 // indirect
-	go.unistack.org/micro/v3 v3.9.8
+	go.unistack.org/micro/v3 v3.9.13
 	golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4 // indirect
 	golang.org/x/sys v0.0.0-20220429233432-b5fbb4746d32 // indirect
 	google.golang.org/genproto v0.0.0-20220429170224-98d788798c3e // indirect
-	google.golang.org/grpc v1.47.0
+	google.golang.org/grpc v1.50.1
 )

go.sum

@@ -20,7 +20,6 @@ github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ3
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/docopt/docopt-go v0.0.0-20180111231733-ee0de3bc6815/go.mod h1:WwZ+bS3ebgob9U8Nd0kOddGdZWjyMGR8Wziv+TBNwSE=
-github.com/ef-ds/deque v1.0.4/go.mod h1:gXDnTC3yqvBcHbq2lcExjtAcVrOnJCbMcZXmuj8Z4tg=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
@@ -31,7 +30,6 @@ github.com/envoyproxy/go-control-plane v0.10.2-0.20220325020618-49ff273808a1/go.
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/flowstack/go-jsonschema v0.1.1/go.mod h1:yL7fNggx1o8rm9RlgXv7hTBWxdBM0rVwpMwimd3F3N0=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
-github.com/golang-jwt/jwt/v4 v4.4.1/go.mod h1:m21LjoU+eqJr34lmDMbreY2eSTRJ1cv77w39/MY0Ch0=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
@@ -48,8 +46,6 @@ github.com/golang/protobuf v1.4.3/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
-github.com/google/gnostic v0.6.6/go.mod h1:Nm8234We1lq6iB9OmlgNv3nH91XLLVZHCDayfA3xq+E=
-github.com/google/gnostic v0.6.8/go.mod h1:Nm8234We1lq6iB9OmlgNv3nH91XLLVZHCDayfA3xq+E=
 github.com/google/gnostic v0.6.9 h1:ZK/5VhkoX835RikCHpSUJV9a+S3e1zLh59YnyWeBW+0=
 github.com/google/gnostic v0.6.9/go.mod h1:Nm8234We1lq6iB9OmlgNv3nH91XLLVZHCDayfA3xq+E=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
@@ -63,7 +59,7 @@ github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
 github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
-github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
+github.com/imdario/mergo v0.3.13/go.mod h1:4lJ1jqUDcsbIECGy0RUJAXNIhg+6ocWgb1ALK2O4oXg=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
@@ -86,10 +82,10 @@ github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2
 github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415/go.mod h1:GwrjFmJcFw6At/Gs6z4yjiIwzuJ1/+UwLxMQDVQXShQ=
 github.com/xeipuuv/gojsonschema v1.2.0/go.mod h1:anYRn/JVcOK2ZgGU+IjEV4nwlhoK5sQluxsYJ78Id3Y=
 go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqeYNgFYFoEGnI=
-go.unistack.org/micro-proto/v3 v3.2.7 h1:zG6d69kHc+oij2lwQ3AfrCgdjiEVRG2A7TlsxjusWs4=
-go.unistack.org/micro-proto/v3 v3.2.7/go.mod h1:ZltVWNECD5yK+40+OCONzGw4OtmSdTpVi8/KFgo9dqM=
-go.unistack.org/micro/v3 v3.9.8 h1:wnNVO3JH+hNK9Hw07iWQ8jcQYnMRPvyYCZRc2IJvymg=
-go.unistack.org/micro/v3 v3.9.8/go.mod h1:SKr1XwfDLsytOixTDei+Ek/tr2OpIjLd9Rg5ET9RqXs=
+go.unistack.org/micro-proto/v3 v3.3.1 h1:nQ0MtWvP2G3QrpOgawVOPhpZZYkq6umTGDqs8FxJYIo=
+go.unistack.org/micro-proto/v3 v3.3.1/go.mod h1:cwRyv8uInM2I7EbU7O8Fx2Ls3N90Uw9UCCcq4olOdfE=
+go.unistack.org/micro/v3 v3.9.13 h1:x1/H4rDgvz2JWXx6UvFiWDyRLxg2Kpp6V1kjzpLlyvo=
+go.unistack.org/micro/v3 v3.9.13/go.mod h1:gI4RkJKHLPW7KV6h4+ZBOZD997MRvFRXMPQIHpozikI=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -106,7 +102,6 @@ golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81R
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20220225172249-27dd8689420f/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4 h1:HVyaeDAYux4pnY+D/SiwmLOR36ewZ4iGQIIrtnuCjFA=
 golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -162,8 +157,8 @@ google.golang.org/grpc v1.33.1/go.mod h1:fr5YgcSWrqhRRxogOsw7RzIpsmvOZ6IcH4kBYTp
 google.golang.org/grpc v1.36.0/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAGRRjU=
 google.golang.org/grpc v1.40.0/go.mod h1:ogyxbiOoUXAkP+4+xa6PZSE9DZgIHtSpzjDTB9KAK34=
 google.golang.org/grpc v1.45.0/go.mod h1:lN7owxKUQEqMfSyQikvvk5tf/6zMPsrK+ONuO11+0rQ=
-google.golang.org/grpc v1.47.0 h1:9n77onPX5F3qfFCqjy9dhn8PbNQsIKeVU04J9G7umt8=
-google.golang.org/grpc v1.47.0/go.mod h1:vN9eftEi1UMyUsIF80+uQXhHjbXYbm0uXoFCACuMGWk=
+google.golang.org/grpc v1.50.1 h1:DS/BukOZWp8s6p4Dt/tOaJaTQyPyOoCcrjroHuCeLzY=
+google.golang.org/grpc v1.50.1/go.mod h1:ZgQEeidpAuNRZ8iRrlBKXZQP1ghovWIVhdJRyCDK+GI=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
 google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQJ+fmap5saPgwCLgHXTUD7jkjRqWcaiX5VyM=
@@ -176,18 +171,18 @@ google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlba
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.28.0 h1:w43yiav+6bVFTBQFZX0r7ipe9JQ1QsbMgHwbBziscLw=
 google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
+google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0 h1:hjy8E9ON/egN1tAYqKb61G10WtihqetD4sz2H+8nIeA=
+gopkg.in/yaml.v3 v3.0.0/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

grpc.go

@@ -78,10 +78,15 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 	} else {
 		header = make(map[string]string, 2)
 	}
-
+	if opts.RequestMetadata != nil {
+		for k, v := range opts.RequestMetadata {
+			header[k] = v
+		}
+	}
 	// set timeout in nanoseconds
 	header["Grpc-Timeout"] = fmt.Sprintf("%dn", opts.RequestTimeout)
 	header["timeout"] = fmt.Sprintf("%dn", opts.RequestTimeout)
+	header["content-type"] = req.ContentType()
 
 	md := gmetadata.New(header)
 	ctx = gmetadata.NewOutgoingContext(ctx, md)
@@ -113,7 +118,7 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 		),
 	}
 
-	if opts := g.getGrpcDialOptions(); opts != nil {
+	if opts := g.getGrpcDialOptions(opts.Context); opts != nil {
 		grpcDialOptions = append(grpcDialOptions, opts...)
 	}
 
@@ -127,15 +132,22 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 	}()
 
 	ch := make(chan error, 1)
+	var gmd gmetadata.MD
+
+	grpcCallOptions := []grpc.CallOption{
+		grpc.CallContentSubtype((&wrapMicroCodec{cf}).Name()),
+	}
+
+	if opts := g.getGrpcCallOptions(opts.Context); opts != nil {
+		grpcCallOptions = append(grpcCallOptions, opts...)
+	}
+
+	if opts.ResponseMetadata != nil {
+		gmd = gmetadata.MD{}
+		grpcCallOptions = append(grpcCallOptions, grpc.Header(&gmd))
+	}
 
 	go func() {
-		grpcCallOptions := []grpc.CallOption{
-			grpc.ForceCodec(&wrapMicroCodec{cf}),
-			grpc.CallContentSubtype((&wrapMicroCodec{cf}).Name()),
-		}
-		if opts := g.getGrpcCallOptions(); opts != nil {
-			grpcCallOptions = append(grpcCallOptions, opts...)
-		}
 		err := cc.Invoke(ctx, methodToGRPC(req.Service(), req.Endpoint()), req.Body(), rsp, grpcCallOptions...)
 		ch <- microError(err)
 	}()
@@ -147,6 +159,13 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 		grr = errors.Timeout("go.micro.client", "%v", ctx.Err())
 	}
 
+	if opts.ResponseMetadata != nil {
+		*opts.ResponseMetadata = metadata.New(gmd.Len())
+		for k, v := range gmd {
+			opts.ResponseMetadata.Set(k, strings.Join(v, ","))
+		}
+	}
+
 	return grr
 }
 
@@ -168,7 +187,7 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 		header["timeout"] = fmt.Sprintf("%dn", opts.StreamTimeout)
 	}
 	// set the content type for the request
-	header["x-content-type"] = req.ContentType()
+	header["content-type"] = req.ContentType()
 
 	md := gmetadata.New(header)
 	ctx = gmetadata.NewOutgoingContext(ctx, md)
@@ -200,7 +219,7 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 		),
 	}
 
-	if opts := g.getGrpcDialOptions(); opts != nil {
+	if opts := g.getGrpcDialOptions(opts.Context); opts != nil {
 		grpcDialOptions = append(grpcDialOptions, opts...)
 	}
 
@@ -216,12 +235,17 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 	}
 
 	grpcCallOptions := []grpc.CallOption{
-		grpc.ForceCodec(wc),
+		// grpc.ForceCodec(wc),
 		grpc.CallContentSubtype(wc.Name()),
 	}
-	if opts := g.getGrpcCallOptions(); opts != nil {
+	if opts := g.getGrpcCallOptions(opts.Context); opts != nil {
 		grpcCallOptions = append(grpcCallOptions, opts...)
 	}
+	var gmd gmetadata.MD
+	if opts.ResponseMetadata != nil {
+		gmd = gmetadata.MD{}
+		grpcCallOptions = append(grpcCallOptions, grpc.Header(&gmd))
+	}
 
 	// create a new cancelling context
 	newCtx, cancel := context.WithCancel(ctx)
@@ -267,6 +291,7 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 	// set the stream as the response
 	val := reflect.ValueOf(rsp).Elem()
 	val.Set(reflect.ValueOf(stream).Elem())
+
 	return nil
 }
 
@@ -391,6 +416,7 @@ func (g *grpcClient) Call(ctx context.Context, req client.Request, rsp interface
 	}
 	// make a copy of call opts
 	callOpts := g.opts.CallOptions
+
 	for _, opt := range opts {
 		opt(&callOpts)
 	}
@@ -728,41 +754,45 @@ func (g *grpcClient) Name() string {
 	return g.opts.Name
 }
 
-func (g *grpcClient) getGrpcDialOptions() []grpc.DialOption {
-	if g.opts.CallOptions.Context == nil {
-		return nil
+func (g *grpcClient) getGrpcDialOptions(ctx context.Context) []grpc.DialOption {
+	var opts []grpc.DialOption
+
+	if g.opts.CallOptions.Context != nil {
+		if v := g.opts.CallOptions.Context.Value(grpcDialOptions{}); v != nil {
+			if vopts, ok := v.([]grpc.DialOption); ok {
+				opts = append(opts, vopts...)
+			}
+		}
 	}
 
-	v := g.opts.CallOptions.Context.Value(grpcDialOptions{})
-
-	if v == nil {
-		return nil
-	}
-
-	opts, ok := v.([]grpc.DialOption)
-
-	if !ok {
-		return nil
+	if ctx != nil {
+		if v := ctx.Value(grpcDialOptions{}); v != nil {
+			if vopts, ok := v.([]grpc.DialOption); ok {
+				opts = append(opts, vopts...)
+			}
+		}
 	}
 
 	return opts
 }
 
-func (g *grpcClient) getGrpcCallOptions() []grpc.CallOption {
-	if g.opts.CallOptions.Context == nil {
-		return nil
+func (g *grpcClient) getGrpcCallOptions(ctx context.Context) []grpc.CallOption {
+	var opts []grpc.CallOption
+
+	if g.opts.CallOptions.Context != nil {
+		if v := g.opts.CallOptions.Context.Value(grpcCallOptions{}); v != nil {
+			if vopts, ok := v.([]grpc.CallOption); ok {
+				opts = append(opts, vopts...)
+			}
+		}
 	}
 
-	v := g.opts.CallOptions.Context.Value(grpcCallOptions{})
-
-	if v == nil {
-		return nil
-	}
-
-	opts, ok := v.([]grpc.CallOption)
-
-	if !ok {
-		return nil
+	if ctx != nil {
+		if v := ctx.Value(grpcCallOptions{}); v != nil {
+			if vopts, ok := v.([]grpc.CallOption); ok {
+				opts = append(opts, vopts...)
+			}
+		}
 	}
 
 	return opts
@@ -771,7 +801,9 @@ func (g *grpcClient) getGrpcCallOptions() []grpc.CallOption {
 func NewClient(opts ...client.Option) client.Client {
 	options := client.NewOptions(opts...)
 	// default content type for grpc
-	options.ContentType = DefaultContentType
+	if options.ContentType == "" {
+		options.ContentType = DefaultContentType
+	}
 
 	rc := &grpcClient{
 		opts: options,

options.go

@@ -70,9 +70,7 @@ func Codec(contentType string, c encoding.Codec) client.Option {
 
 type maxRecvMsgSizeKey struct{}
 
-//
 // MaxRecvMsgSize set the maximum size of message that client can receive.
-//
 func MaxRecvMsgSize(s int) client.Option {
 	return func(o *client.Options) {
 		if o.Context == nil {
@@ -84,9 +82,7 @@ func MaxRecvMsgSize(s int) client.Option {
 
 type maxSendMsgSizeKey struct{}
 
-//
 // MaxSendMsgSize set the maximum size of message that client can send.
-//
 func MaxSendMsgSize(s int) client.Option {
 	return func(o *client.Options) {
 		if o.Context == nil {
@@ -98,9 +94,7 @@ func MaxSendMsgSize(s int) client.Option {
 
 type grpcDialOptions struct{}
 
-//
 // DialOptions to be used to configure gRPC dial options
-//
 func DialOptions(opts ...grpc.DialOption) client.CallOption {
 	return func(o *client.CallOptions) {
 		if o.Context == nil {
@@ -112,9 +106,7 @@ func DialOptions(opts ...grpc.DialOption) client.CallOption {
 
 type grpcCallOptions struct{}
 
-//
 // CallOptions to be used to configure gRPC call options
-//
 func CallOptions(opts ...grpc.CallOption) client.CallOption {
 	return func(o *client.CallOptions) {
 		if o.Context == nil {

request.go

@@ -38,15 +38,12 @@ func methodToGRPC(service, method string) string {
 	return fmt.Sprintf("/%s.%s/%s", service, mParts[0], mParts[1])
 }
 
-func newGRPCRequest(service, method string, request interface{}, contentType string, reqOpts ...client.RequestOption) client.Request {
-	var opts client.RequestOptions
-	for _, o := range reqOpts {
-		o(&opts)
-	}
+func newGRPCRequest(service, method string, request interface{}, contentType string, opts ...client.RequestOption) client.Request {
+	options := client.NewRequestOptions(opts...)
 
 	// set the content-type specified
-	if len(opts.ContentType) > 0 {
-		contentType = opts.ContentType
+	if len(options.ContentType) > 0 {
+		contentType = options.ContentType
 	}
 
 	return &grpcRequest{
@@ -54,7 +51,7 @@ func newGRPCRequest(service, method string, request interface{}, contentType str
 		method:      method,
 		request:     request,
 		contentType: contentType,
-		opts:        opts,
+		opts:        options,
 	}
 }
 

response.go

@@ -23,7 +23,7 @@ func (r *response) Codec() codec.Codec {
 func (r *response) Header() metadata.Metadata {
 	meta, err := r.stream.Header()
 	if err != nil {
-		return metadata.New(0)
+		return nil
 	}
 	md := metadata.New(len(meta))
 	for k, v := range meta {