Refactor loops over SupportedMediaTypes() where mediaType is used to match a single SerializerInfo{}

We have an existing helper function for this:  runtime.SerializerInfoForMediaType()

This is common prep-work for encoding runtime.Objects into JSON/YAML for transmission over the wire or writing to ComponentConfigs.

cmd/kube-proxy/app/BUILD

@@ -47,7 +47,6 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/serializer:go_default_library",
-        "//staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/server/healthz:go_default_library",

cmd/kube-proxy/app/server.go

@@ -32,7 +32,6 @@ import (
 	v1meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/server/healthz"
@@ -334,19 +333,13 @@ func (o *Options) runLoop() error {
 }
 
 func (o *Options) writeConfigFile() error {
-	var encoder runtime.Encoder
+	const mediaType = runtime.ContentTypeYAML
-	mediaTypes := o.codecs.SupportedMediaTypes()
+	info, ok := runtime.SerializerInfoForMediaType(o.codecs.SupportedMediaTypes(), mediaType)
-	for _, info := range mediaTypes {
+	if !ok {
-		if info.MediaType == "application/yaml" {
+		return fmt.Errorf("unable to locate encoder -- %q is not a supported media type", mediaType)
-			encoder = info.Serializer
-			break
-		}
 	}
-	if encoder == nil {
+
-		return errors.New("unable to locate yaml encoder")
+	encoder := o.codecs.EncoderForVersion(info.Serializer, v1alpha1.SchemeGroupVersion)
-	}
-	encoder = json.NewYAMLSerializer(json.DefaultMetaFactory, o.scheme, o.scheme)
-	encoder = o.codecs.EncoderForVersion(encoder, v1alpha1.SchemeGroupVersion)
 
 	configFile, err := os.Create(o.WriteConfigTo)
 	if err != nil {

cmd/kube-scheduler/app/options/BUILD

@@ -23,7 +23,6 @@ go_library(
         "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
-        "//staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/uuid:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/validation/field:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/server/options:go_default_library",

cmd/kube-scheduler/app/options/configfile.go

@@ -17,12 +17,11 @@ limitations under the License.
 package options
 
 import (
-	"errors"
+	"fmt"
 	"io/ioutil"
 	"os"
 
 	"k8s.io/apimachinery/pkg/runtime"
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
 	kubeschedulerconfig "k8s.io/kubernetes/pkg/scheduler/apis/config"
 	kubeschedulerscheme "k8s.io/kubernetes/pkg/scheduler/apis/config/scheme"
 	kubeschedulerconfigv1alpha1 "k8s.io/kubernetes/pkg/scheduler/apis/config/v1alpha1"
@@ -48,19 +47,13 @@ func loadConfig(data []byte) (*kubeschedulerconfig.KubeSchedulerConfiguration, e
 
 // WriteConfigFile writes the config into the given file name as YAML.
 func WriteConfigFile(fileName string, cfg *kubeschedulerconfig.KubeSchedulerConfiguration) error {
-	var encoder runtime.Encoder
+	const mediaType = runtime.ContentTypeYAML
-	mediaTypes := kubeschedulerscheme.Codecs.SupportedMediaTypes()
+	info, ok := runtime.SerializerInfoForMediaType(kubeschedulerscheme.Codecs.SupportedMediaTypes(), mediaType)
-	for _, info := range mediaTypes {
+	if !ok {
-		if info.MediaType == "application/yaml" {
+		return fmt.Errorf("unable to locate encoder -- %q is not a supported media type", mediaType)
-			encoder = info.Serializer
-			break
-		}
 	}
-	if encoder == nil {
+
-		return errors.New("unable to locate yaml encoder")
+	encoder := kubeschedulerscheme.Codecs.EncoderForVersion(info.Serializer, kubeschedulerconfigv1alpha1.SchemeGroupVersion)
-	}
-	encoder = json.NewYAMLSerializer(json.DefaultMetaFactory, kubeschedulerscheme.Scheme, kubeschedulerscheme.Scheme)
-	encoder = kubeschedulerscheme.Codecs.EncoderForVersion(encoder, kubeschedulerconfigv1alpha1.SchemeGroupVersion)
 
 	configFile, err := os.Create(fileName)
 	if err != nil {

cmd/kubeadm/app/util/marshal.go

@@ -42,7 +42,7 @@ func MarshalToYaml(obj runtime.Object, gv schema.GroupVersion) ([]byte, error) {
 // TODO: Is specifying the gv really needed here?
 // TODO: Can we support json out of the box easily here?
 func MarshalToYamlForCodecs(obj runtime.Object, gv schema.GroupVersion, codecs serializer.CodecFactory) ([]byte, error) {
-	mediaType := "application/yaml"
+	const mediaType = runtime.ContentTypeYAML
 	info, ok := runtime.SerializerInfoForMediaType(codecs.SupportedMediaTypes(), mediaType)
 	if !ok {
 		return []byte{}, errors.Errorf("unsupported media type %q", mediaType)
@@ -61,7 +61,7 @@ func UnmarshalFromYaml(buffer []byte, gv schema.GroupVersion) (runtime.Object, e
 // TODO: Is specifying the gv really needed here?
 // TODO: Can we support json out of the box easily here?
 func UnmarshalFromYamlForCodecs(buffer []byte, gv schema.GroupVersion, codecs serializer.CodecFactory) (runtime.Object, error) {
-	mediaType := "application/yaml"
+	const mediaType = runtime.ContentTypeYAML
 	info, ok := runtime.SerializerInfoForMediaType(codecs.SupportedMediaTypes(), mediaType)
 	if !ok {
 		return nil, errors.Errorf("unsupported media type %q", mediaType)

staging/src/k8s.io/apiserver/pkg/audit/request.go

@@ -197,22 +197,22 @@ func LogResponseObject(ae *auditinternal.Event, obj runtime.Object, gv schema.Gr
 }
 
 func encodeObject(obj runtime.Object, gv schema.GroupVersion, serializer runtime.NegotiatedSerializer) (*runtime.Unknown, error) {
-	supported := serializer.SupportedMediaTypes()
+	const mediaType = runtime.ContentTypeJSON
-	for i := range supported {
+	info, ok := runtime.SerializerInfoForMediaType(serializer.SupportedMediaTypes(), mediaType)
-		if supported[i].MediaType == "application/json" {
+	if !ok {
-			enc := serializer.EncoderForVersion(supported[i].Serializer, gv)
+		return nil, fmt.Errorf("unable to locate encoder -- %q is not a supported media type", mediaType)
-			var buf bytes.Buffer
-			if err := enc.Encode(obj, &buf); err != nil {
-				return nil, fmt.Errorf("encoding failed: %v", err)
-			}
-
-			return &runtime.Unknown{
-				Raw:         buf.Bytes(),
-				ContentType: runtime.ContentTypeJSON,
-			}, nil
-		}
 	}
-	return nil, fmt.Errorf("no json encoder found")
+
+	enc := serializer.EncoderForVersion(info.Serializer, gv)
+	var buf bytes.Buffer
+	if err := enc.Encode(obj, &buf); err != nil {
+		return nil, fmt.Errorf("encoding failed: %v", err)
+	}
+
+	return &runtime.Unknown{
+		Raw:         buf.Bytes(),
+		ContentType: runtime.ContentTypeJSON,
+	}, nil
 }
 
 // LogAnnotation fills in the Annotations according to the key value pair.

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/negotiation/negotiate.go

@@ -79,10 +79,7 @@ func NegotiateInputSerializerForMediaType(mediaType string, streaming bool, ns r
 		mediaType = mediaTypes[0].MediaType
 	}
 	if mediaType, _, err := mime.ParseMediaType(mediaType); err == nil {
-		for _, info := range mediaTypes {
+		if info, ok := runtime.SerializerInfoForMediaType(mediaTypes, mediaType); ok {
-			if info.MediaType != mediaType {
-				continue
-			}
 			return info, nil
 		}
 	}

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/watch.go

@@ -94,17 +94,12 @@ func serveWatch(watcher watch.Interface, scope *RequestScope, mediaTypeOptions n
 	var embeddedEncoder runtime.Encoder
 	contentKind, contentSerializer, transform := targetEncodingForTransform(scope, mediaTypeOptions, req)
 	if transform {
-		var embedded runtime.Serializer
+		info, ok := runtime.SerializerInfoForMediaType(contentSerializer.SupportedMediaTypes(), serializer.MediaType)
-		for _, supported := range contentSerializer.SupportedMediaTypes() {
+		if !ok {
-			if supported.MediaType == serializer.MediaType {
-				embedded = supported.Serializer
-			}
-		}
-		if embedded == nil {
 			scope.err(fmt.Errorf("no encoder for %q exists in the requested target %#v", serializer.MediaType, contentSerializer), w, req)
 			return
 		}
-		embeddedEncoder = contentSerializer.EncoderForVersion(embedded, contentKind.GroupVersion())
+		embeddedEncoder = contentSerializer.EncoderForVersion(info.Serializer, contentKind.GroupVersion())
 	} else {
 		embeddedEncoder = scope.Serializer.EncoderForVersion(serializer.Serializer, contentKind.GroupVersion())
 	}

staging/src/k8s.io/cli-runtime/pkg/resource/scheme.go

@@ -56,18 +56,12 @@ func (dynamicCodec) Encode(obj runtime.Object, w io.Writer) error {
 	return unstructured.UnstructuredJSONScheme.Encode(obj, w)
 }
 
-// ContentConfig returns a rest.ContentConfig for dynamic types.  It includes enough codecs to act as a "normal"
+// UnstructuredPlusDefaultContentConfig returns a rest.ContentConfig for dynamic types.  It includes enough codecs to act as a "normal"
 // serializer for the rest.client with options, status and the like.
 func UnstructuredPlusDefaultContentConfig() rest.ContentConfig {
-	var jsonInfo runtime.SerializerInfo
 	// TODO: scheme.Codecs here should become "pkg/apis/server/scheme" which is the minimal core you need
 	// to talk to a kubernetes server
-	for _, info := range scheme.Codecs.SupportedMediaTypes() {
+	jsonInfo, _ := runtime.SerializerInfoForMediaType(scheme.Codecs.SupportedMediaTypes(), runtime.ContentTypeJSON)
-		if info.MediaType == runtime.ContentTypeJSON {
-			jsonInfo = info
-			break
-		}
-	}
 
 	jsonInfo.Serializer = dynamicCodec{}
 	jsonInfo.PrettySerializer = nil

staging/src/k8s.io/client-go/deprecated-dynamic/bad_debt.go

@@ -59,15 +59,9 @@ func (dynamicCodec) Encode(obj runtime.Object, w io.Writer) error {
 // ContentConfig returns a rest.ContentConfig for dynamic types.
 // Deprecated only used by test code and its wrong
 func ContentConfig() rest.ContentConfig {
-	var jsonInfo runtime.SerializerInfo
 	// TODO: scheme.Codecs here should become "pkg/apis/server/scheme" which is the minimal core you need
 	// to talk to a kubernetes server
-	for _, info := range scheme.Codecs.SupportedMediaTypes() {
+	jsonInfo, _ := runtime.SerializerInfoForMediaType(scheme.Codecs.SupportedMediaTypes(), runtime.ContentTypeJSON)
-		if info.MediaType == runtime.ContentTypeJSON {
-			jsonInfo = info
-			break
-		}
-	}
 
 	jsonInfo.Serializer = dynamicCodec{}
 	jsonInfo.PrettySerializer = nil