Add ConfigUnmarshaler interface to allow mutations on the parsed Config

config/configtest/configtest.go

@@ -17,8 +17,8 @@ package configtest
 import (
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config"
-	"go.opentelemetry.io/collector/config/configloader"
 	"go.opentelemetry.io/collector/config/configparser"
+	"go.opentelemetry.io/collector/config/configunmarshaler"
 )
 
 // LoadConfig loads a config from file, and does NOT validate the configuration.
@@ -28,8 +28,8 @@ func LoadConfig(fileName string, factories component.Factories) (*config.Config,
 	if err != nil {
 		return nil, err
 	}
-	// Load the config using the given factories.
-	return configloader.Load(cp, factories)
+	// Unmarshal the config using the given factories.
+	return configunmarshaler.NewDefault().Unmarshal(cp, factories)
 }
 
 // LoadConfigAndValidate loads a config from the file, and validates the configuration.

config/configloader/config.go → config/configunmarshaler/defaultunmarshaler.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package configloader
+package configunmarshaler
 
 import (
 	"fmt"
@@ -26,8 +26,8 @@ import (
 	"go.opentelemetry.io/collector/config/configparser"
 )
 
-// These are errors that can be returned by Load(). Note that error codes are not part
-// of Load()'s public API, they are for internal unit testing only.
+// These are errors that can be returned by Unmarshal(). Note that error codes are not part
+// of Unmarshal()'s public API, they are for internal unit testing only.
 type configErrorCode int
 
 const (
@@ -89,12 +89,20 @@ type pipelineSettings struct {
 	Exporters  []string `mapstructure:"exporters"`
 }
 
-// Load loads a Config from Parser.
-// After loading the config, `Validate()` must be called to validate.
-func Load(v *configparser.Parser, factories component.Factories) (*config.Config, error) {
+type defaultUnmarshaler struct{}
+
+// NewDefault returns a default ConfigUnmarshaler that unmarshalls every configuration
+// using the custom unmarshaler if present or default to strict
+func NewDefault() ConfigUnmarshaler {
+	return &defaultUnmarshaler{}
+}
+
+// Unmarshal the Config from a Parser.
+// After the config is unmarshalled, `Validate()` must be called to validate.
+func (*defaultUnmarshaler) Unmarshal(v *configparser.Parser, factories component.Factories) (*config.Config, error) {
 	var cfg config.Config
 
-	// Load the config.
+	// Unmarshal the config.
 
 	// Struct to validate top level sections.
 	var rawCfg configSettings
@@ -111,34 +119,34 @@ func Load(v *configparser.Parser, factories component.Factories) (*config.Config
 
 	// Start with the service extensions.
 
-	extensions, err := loadExtensions(cast.ToStringMap(v.Get(extensionsKeyName)), factories.Extensions)
+	extensions, err := unmarshalExtensions(cast.ToStringMap(v.Get(extensionsKeyName)), factories.Extensions)
 	if err != nil {
 		return nil, err
 	}
 	cfg.Extensions = extensions
 
-	// Load data components (receivers, exporters, and processors).
+	// Unmarshal data components (receivers, exporters, and processors).
 
-	receivers, err := loadReceivers(cast.ToStringMap(v.Get(receiversKeyName)), factories.Receivers)
+	receivers, err := unmarshalReceivers(cast.ToStringMap(v.Get(receiversKeyName)), factories.Receivers)
 	if err != nil {
 		return nil, err
 	}
 	cfg.Receivers = receivers
 
-	exporters, err := loadExporters(cast.ToStringMap(v.Get(exportersKeyName)), factories.Exporters)
+	exporters, err := unmarshalExporters(cast.ToStringMap(v.Get(exportersKeyName)), factories.Exporters)
 	if err != nil {
 		return nil, err
 	}
 	cfg.Exporters = exporters
 
-	processors, err := loadProcessors(cast.ToStringMap(v.Get(processorsKeyName)), factories.Processors)
+	processors, err := unmarshalProcessors(cast.ToStringMap(v.Get(processorsKeyName)), factories.Processors)
 	if err != nil {
 		return nil, err
 	}
 	cfg.Processors = processors
 
-	// Load the service and its data pipelines.
-	service, err := loadService(rawCfg.Service)
+	// Unmarshal the service and its data pipelines.
+	service, err := unmarshalService(rawCfg.Service)
 	if err != nil {
 		return nil, err
 	}
@@ -175,7 +183,7 @@ func errorDuplicateName(component string, id config.ComponentID) error {
 	}
 }
 
-func loadExtensions(exts map[string]interface{}, factories map[config.Type]component.ExtensionFactory) (config.Extensions, error) {
+func unmarshalExtensions(exts map[string]interface{}, factories map[config.Type]component.ExtensionFactory) (config.Extensions, error) {
 	// Prepare resulting map.
 	extensions := make(config.Extensions)
 
@@ -217,7 +225,7 @@ func loadExtensions(exts map[string]interface{}, factories map[config.Type]compo
 	return extensions, nil
 }
 
-func loadService(rawService serviceSettings) (config.Service, error) {
+func unmarshalService(rawService serviceSettings) (config.Service, error) {
 	var ret config.Service
 	ret.Extensions = make([]config.ComponentID, 0, len(rawService.Extensions))
 	for _, extIDStr := range rawService.Extensions {
@@ -230,7 +238,7 @@ func loadService(rawService serviceSettings) (config.Service, error) {
 
 	// Process the pipelines first so in case of error on them it can be properly
 	// reported.
-	pipelines, err := loadPipelines(rawService.Pipelines)
+	pipelines, err := unmarshalPipelines(rawService.Pipelines)
 	ret.Pipelines = pipelines
 
 	return ret, err
@@ -252,7 +260,7 @@ func LoadReceiver(componentConfig *configparser.Parser, id config.ComponentID, f
 	return receiverCfg, nil
 }
 
-func loadReceivers(recvs map[string]interface{}, factories map[config.Type]component.ReceiverFactory) (config.Receivers, error) {
+func unmarshalReceivers(recvs map[string]interface{}, factories map[config.Type]component.ReceiverFactory) (config.Receivers, error) {
 	// Prepare resulting map.
 	receivers := make(config.Receivers)
 
@@ -289,7 +297,7 @@ func loadReceivers(recvs map[string]interface{}, factories map[config.Type]compo
 	return receivers, nil
 }
 
-func loadExporters(exps map[string]interface{}, factories map[config.Type]component.ExporterFactory) (config.Exporters, error) {
+func unmarshalExporters(exps map[string]interface{}, factories map[config.Type]component.ExporterFactory) (config.Exporters, error) {
 	// Prepare resulting map.
 	exporters := make(config.Exporters)
 
@@ -331,7 +339,7 @@ func loadExporters(exps map[string]interface{}, factories map[config.Type]compon
 	return exporters, nil
 }
 
-func loadProcessors(procs map[string]interface{}, factories map[config.Type]component.ProcessorFactory) (config.Processors, error) {
+func unmarshalProcessors(procs map[string]interface{}, factories map[config.Type]component.ProcessorFactory) (config.Processors, error) {
 	// Prepare resulting map.
 	processors := make(config.Processors)
 
@@ -373,7 +381,7 @@ func loadProcessors(procs map[string]interface{}, factories map[config.Type]comp
 	return processors, nil
 }
 
-func loadPipelines(pipelinesConfig map[string]pipelineSettings) (config.Pipelines, error) {
+func unmarshalPipelines(pipelinesConfig map[string]pipelineSettings) (config.Pipelines, error) {
 	// Prepare resulting map.
 	pipelines := make(config.Pipelines)
 

config/configloader/config_test.go → config/configunmarshaler/defaultunmarshaler_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package configloader
+package configunmarshaler
 
 import (
 	"os"
@@ -33,7 +33,7 @@ func TestDecodeConfig(t *testing.T) {
 	factories, err := testcomponents.ExampleComponents()
 	assert.NoError(t, err)
 
-	// Load the config
+	// Unmarshal the config
 	cfg, err := loadConfigFile(t, path.Join(".", "testdata", "valid-config.yaml"), factories)
 	require.NoError(t, err, "Unable to load config")
 
@@ -186,7 +186,7 @@ func TestSimpleConfig(t *testing.T) {
 			factories, err := testcomponents.ExampleComponents()
 			assert.NoError(t, err)
 
-			// Load the config
+			// Unmarshal the config
 			cfg, err := loadConfigFile(t, path.Join(".", "testdata", test.name+".yaml"), factories)
 			require.NoError(t, err, "Unable to load config")
 
@@ -276,7 +276,7 @@ func TestEscapedEnvVars(t *testing.T) {
 	factories, err := testcomponents.ExampleComponents()
 	assert.NoError(t, err)
 
-	// Load the config
+	// Unmarshal the config
 	cfg, err := loadConfigFile(t, path.Join(".", "testdata", "simple-config-with-escaped-env.yaml"), factories)
 	require.NoError(t, err, "Unable to load config")
 
@@ -459,8 +459,8 @@ func loadConfigFile(t *testing.T, fileName string, factories component.Factories
 	v, err := configparser.NewParserFromFile(fileName)
 	require.NoError(t, err)
 
-	// Load the config from the configparser.Parser using the given factories.
-	return Load(v, factories)
+	// Unmarshal the config from the configparser.Parser using the given factories.
+	return NewDefault().Unmarshal(v, factories)
 }
 
 type nestedConfig struct {

config/configloader/doc.go → config/configunmarshaler/doc.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package configloader implements configuration loading from a config.Parser.
+// Package configunmarshaler implements configuration unmarshalling from a config.Parser.
 // The implementation relies on registered factories that allow creating
 // default configuration for each type of receiver/exporter/processor.
-package configloader
+package configunmarshaler

config/configunmarshaler/unmarshaler.go

@@ -0,0 +1,27 @@
+// 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 configunmarshaler
+
+import (
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/config"
+	"go.opentelemetry.io/collector/config/configparser"
+)
+
+// ConfigUnmarshaler is the interface that unmarshalls the collector configuration from the configparser.Parser.
+type ConfigUnmarshaler interface {
+	// Unmarshal the configuration from the given parser and factories.
+	Unmarshal(v *configparser.Parser, factories component.Factories) (*config.Config, error)
+}

service/collector.go

@@ -35,8 +35,8 @@ import (
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configcheck"
-	"go.opentelemetry.io/collector/config/configloader"
 	"go.opentelemetry.io/collector/config/configtelemetry"
+	"go.opentelemetry.io/collector/config/configunmarshaler"
 	"go.opentelemetry.io/collector/config/experimental/configsource"
 	"go.opentelemetry.io/collector/consumer/consumererror"
 	"go.opentelemetry.io/collector/extension/ballastextension"
@@ -81,7 +81,8 @@ type Collector struct {
 
 	factories component.Factories
 
-	parserProvider parserprovider.ParserProvider
+	parserProvider    parserprovider.ParserProvider
+	configUnmarshaler configunmarshaler.ConfigUnmarshaler
 
 	// shutdownChan is used to terminate the collector.
 	shutdownChan chan struct{}
@@ -102,14 +103,26 @@ func New(set CollectorSettings) (*Collector, error) {
 	}
 
 	col := &Collector{
-		info:         set.BuildInfo,
-		factories:    set.Factories,
-		stateChannel: make(chan State, Closed+1),
+		info:              set.BuildInfo,
+		factories:         set.Factories,
+		stateChannel:      make(chan State, Closed+1),
+		parserProvider:    set.ParserProvider,
+		configUnmarshaler: set.ConfigUnmarshaler,
 		// We use a negative in the settings not to break the existing
 		// behavior. Internally, allowGracefulShutodwn is more readable.
 		allowGracefulShutodwn: !set.DisableGracefulShutdown,
 	}
 
+	if col.parserProvider == nil {
+		// use default provider.
+		col.parserProvider = parserprovider.Default()
+	}
+
+	if col.configUnmarshaler == nil {
+		// use default provider.
+		col.configUnmarshaler = configunmarshaler.NewDefault()
+	}
+
 	rootCmd := &cobra.Command{
 		Use:     set.BuildInfo.Command,
 		Version: set.BuildInfo.Version,
@@ -147,13 +160,6 @@ func New(set CollectorSettings) (*Collector, error) {
 	rootCmd.Flags().AddGoFlagSet(flagSet)
 	col.rootCmd = rootCmd
 
-	parserProvider := set.ParserProvider
-	if parserProvider == nil {
-		// use default provider.
-		parserProvider = parserprovider.Default()
-	}
-	col.parserProvider = parserProvider
-
 	return col, nil
 }
 
@@ -240,7 +246,7 @@ func (col *Collector) setupConfigurationComponents(ctx context.Context) error {
 		return fmt.Errorf("cannot load configuration's parser: %w", err)
 	}
 
-	cfg, err := configloader.Load(cp, col.factories)
+	cfg, err := col.configUnmarshaler.Unmarshal(cp, col.factories)
 	if err != nil {
 		return fmt.Errorf("cannot load configuration: %w", err)
 	}

service/collector_test.go

@@ -36,6 +36,7 @@ import (
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configparser"
+	"go.opentelemetry.io/collector/config/configunmarshaler"
 	"go.opentelemetry.io/collector/service/defaultcomponents"
 	"go.opentelemetry.io/collector/service/internal/builder"
 	"go.opentelemetry.io/collector/service/parserprovider"
@@ -329,11 +330,12 @@ func TestCollector_reloadService(t *testing.T) {
 			}
 
 			col := Collector{
-				logger:         zap.NewNop(),
-				tracerProvider: trace.NewNoopTracerProvider(),
-				parserProvider: tt.parserProvider,
-				factories:      factories,
-				service:        tt.service,
+				logger:            zap.NewNop(),
+				tracerProvider:    trace.NewNoopTracerProvider(),
+				parserProvider:    tt.parserProvider,
+				configUnmarshaler: configunmarshaler.NewDefault(),
+				factories:         factories,
+				service:           tt.service,
 			}
 
 			err := col.reloadService(ctx)

service/internal/builder/pipelines_builder_test.go

@@ -181,7 +181,7 @@ func testPipeline(t *testing.T, pipelineName string, exporterIDs []config.Compon
 	factories, err := testcomponents.ExampleComponents()
 	assert.NoError(t, err)
 	cfg, err := configtest.LoadConfigAndValidate("testdata/pipelines_builder.yaml", factories)
-	// Load the config
+	// Unmarshal the config
 	require.Nil(t, err)
 
 	// BuildProcessors the pipeline