Add config marshaler.

config/common.go

@@ -15,6 +15,7 @@
 package config // import "go.opentelemetry.io/collector/config"
 import (
 	"go.opentelemetry.io/collector/confmap"
+	"go.opentelemetry.io/collector/service/configmarshaler/configencoder"
 )
 
 // Type is the component type as it is used in the config.
@@ -32,6 +33,9 @@ type Unmarshallable interface {
 	// Unmarshal is a function that unmarshalls a confmap.Conf into the unmarshable struct in a custom way.
 	// The confmap.Conf for this specific component may be nil or empty if no config available.
 	Unmarshal(component *confmap.Conf) error
+	// Marshal is a function that marshals the config into an interface to be encoded by
+	// the YAML encoder. Provides the configencoder.Encoder.
+	Marshal(encoder configencoder.Encoder) (interface{}, error)
 }
 
 // DataType is a special Type that represents the data types supported by the collector. We currently support

config/configcompression/compressionType.go

@@ -32,6 +32,10 @@ func IsCompressed(compressionType CompressionType) bool {
 	return compressionType != empty && compressionType != none
 }
 
+func (ct CompressionType) MarshalText() (out []byte, err error) {
+	return []byte(ct), nil
+}
+
 func (ct *CompressionType) UnmarshalText(in []byte) error {
 	switch typ := CompressionType(in); typ {
 	case Gzip,

config/configtelemetry/configtelemetry.go

@@ -41,6 +41,7 @@ const (
 // that every component should generate.
 type Level int32
 
+var _ encoding.TextMarshaler = (*Level)(nil)
 var _ encoding.TextUnmarshaler = (*Level)(nil)
 
 func (l Level) String() string {
@@ -57,6 +58,11 @@ func (l Level) String() string {
 	return "unknown"
 }
 
+// MarshalText marshals Level to text.
+func (l Level) MarshalText() (text []byte, err error) {
+	return []byte(l.String()), nil
+}
+
 // UnmarshalText unmarshalls text to a Level.
 func (l *Level) UnmarshalText(text []byte) error {
 	if l == nil {

config/identifiable.go

@@ -69,6 +69,11 @@ func (id ComponentID) Name() string {
 	return id.nameVal
 }
 
+// MarshalText implements the encoding.TextMarshaler interface.
+func (id ComponentID) MarshalText() (text []byte, err error) {
+	return []byte(id.String()), nil
+}
+
 // UnmarshalText implements the encoding.TextUnmarshaler interface.
 func (id *ComponentID) UnmarshalText(text []byte) error {
 	idStr := string(text)

receiver/otlpreceiver/config.go

@@ -21,6 +21,7 @@ import (
 	"go.opentelemetry.io/collector/config/configgrpc"
 	"go.opentelemetry.io/collector/config/confighttp"
 	"go.opentelemetry.io/collector/confmap"
+	"go.opentelemetry.io/collector/service/configmarshaler/configencoder"
 )
 
 const (
@@ -32,8 +33,8 @@ const (
 
 // Protocols is the configuration for the supported protocols.
 type Protocols struct {
-	GRPC *configgrpc.GRPCServerSettings `mapstructure:"grpc"`
-	HTTP *confighttp.HTTPServerSettings `mapstructure:"http"`
+	GRPC *configgrpc.GRPCServerSettings `mapstructure:"grpc,omitempty"`
+	HTTP *confighttp.HTTPServerSettings `mapstructure:"http,omitempty"`
 }
 
 // Config defines configuration for OTLP receiver.
@@ -82,3 +83,7 @@ func (cfg *Config) Unmarshal(componentParser *confmap.Conf) error {
 
 	return nil
 }
+
+func (cfg *Config) Marshal(enc configencoder.Encoder) (interface{}, error) {
+	return enc.Encode(cfg)
+}

service/configmarshaler/configencoder/encoder.go

@@ -0,0 +1,20 @@
+// Copyright  The OpenTelemetry 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 configencoder // import "go.opentelemetry.io/collector/service/configmarshaler/configencoder"
+
+type Encoder interface {
+	// Encode encodes the input into the output.
+	Encode(in interface{}) (out interface{}, err error)
+}

service/configmarshaler/configencoder/encodertest/encoder.go

@@ -0,0 +1,40 @@
+// Copyright  The OpenTelemetry 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 encodertest // import "go.opentelemetry.io/collector/service/configmarshaler/configencoder/encodertest"
+
+import "go.opentelemetry.io/collector/service/configmarshaler/configencoder"
+
+// nopEncoder mocks a configencoder.Encoder for test purposes.
+type nopEncoder struct {
+	err error
+}
+
+var _ configencoder.Encoder = (*nopEncoder)(nil)
+
+// NewNop returns a new instance of nopEncoder.
+func NewNop() configencoder.Encoder {
+	return &nopEncoder{}
+}
+
+// NewNopWithErr returns a new instance of nopEncoder with
+// an error set.
+func NewNopWithErr(err error) configencoder.Encoder {
+	return &nopEncoder{err}
+}
+
+// Encode returns nil and the error if it is set.
+func (ne nopEncoder) Encode(interface{}) (interface{}, error) {
+	return nil, ne.err
+}

service/configmarshaler/configencoder/encodertest/encoder_test.go

@@ -0,0 +1,36 @@
+// Copyright  The OpenTelemetry 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 encodertest
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewNop(t *testing.T) {
+	encoder := NewNop()
+	got, err := encoder.Encode(nil)
+	require.NoError(t, err)
+	require.Nil(t, got)
+}
+
+func TestNewNopWithErr(t *testing.T) {
+	wantErr := errors.New("test")
+	encoder := NewNopWithErr(wantErr)
+	_, err := encoder.Encode(nil)
+	require.Equal(t, wantErr, err)
+}