Add factories and component types to support logs data type

We are planning on experimenting with logs data type in the Collector.
This commit introduces factories and components types for logs and
implements pipeline building for logs.

The data.Log struct is for now empty. We need to wait for OTLP protocol
to define the log data format and we will use it in data.Log.

data.Log is in internal package since logs support is experimental
and is not intended for public usage yet.

Resolves #957

Author: Tigran Najaryan

component/exporter.go

@@ -23,7 +23,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector/consumer"
 )
 
-// Exporter defines functions that trace and metric exporters must implement.
+// Exporter defines functions that all exporters must implement.
 type Exporter interface {
 	Component
 }
@@ -33,13 +33,13 @@ type TraceExporterBase interface {
 	Exporter
 }
 
-// TraceExporterOld is a TraceConsumer that is also an Exporter.
+// TraceExporterOld is a TraceExporter that can consume old-style traces.
 type TraceExporterOld interface {
 	consumer.TraceConsumerOld
 	TraceExporterBase
 }
 
-// TraceExporter is an TraceConsumer that is also an Exporter.
+// TraceExporter is a TraceExporter that can consume new-style traces.
 type TraceExporter interface {
 	consumer.TraceConsumer
 	TraceExporterBase
@@ -50,18 +50,24 @@ type MetricsExporterBase interface {
 	Exporter
 }
 
-// MetricsExporterOld is a MetricsConsumer that is also an Exporter.
+// MetricsExporterOld is a TraceExporter that can consume old-style metrics.
 type MetricsExporterOld interface {
 	consumer.MetricsConsumerOld
 	MetricsExporterBase
 }
 
-// MetricsExporter is a MetricsConsumer that is also an Exporter.
+// MetricsExporter is a TraceExporter that can consume new-style metrics.
 type MetricsExporter interface {
 	consumer.MetricsConsumer
 	MetricsExporterBase
 }
 
+// LogExporter is a LogConsumer that is also an Exporter.
+type LogExporter interface {
+	Exporter
+	consumer.LogConsumer
+}
+
 // ExporterFactoryBase defines the common functions for all exporter factories.
 type ExporterFactoryBase interface {
 	Factory
@@ -87,7 +93,7 @@ type ExporterFactoryOld interface {
 	CreateMetricsExporter(logger *zap.Logger, cfg configmodels.Exporter) (MetricsExporterOld, error)
 }
 
-// ExporterCreateParams is passed to ExporterFactory.Create* functions.
+// ExporterCreateParams is passed to Create*Exporter functions.
 type ExporterCreateParams struct {
 	// Logger that the factory can use during creation and can pass to the created
 	// component to be used later as well.
@@ -111,3 +117,17 @@ type ExporterFactory interface {
 	CreateMetricsExporter(ctx context.Context, params ExporterCreateParams,
 		cfg configmodels.Exporter) (MetricsExporter, error)
 }
+
+// LogExporterFactory can create a LogExporter.
+type LogExporterFactory interface {
+	ExporterFactoryBase
+
+	// CreateLogExporter creates an exporter based on the config.
+	// If the exporter type does not support logs or if the config is not valid
+	// error will be returned instead.
+	CreateLogExporter(
+		ctx context.Context,
+		params ExporterCreateParams,
+		cfg configmodels.Exporter,
+	) (LogExporter, error)
+}

component/processor.go

@@ -37,13 +37,13 @@ type TraceProcessorBase interface {
 	Processor
 }
 
-// TraceProcessorOld composes TraceConsumer with some additional processor-specific functions.
+// TraceProcessorOld is a processor that can consume old-style traces.
 type TraceProcessorOld interface {
 	consumer.TraceConsumerOld
 	TraceProcessorBase
 }
 
-// TraceProcessor composes TraceConsumer with some additional processor-specific functions.
+// TraceProcessor is a processor that can consume traces.
 type TraceProcessor interface {
 	consumer.TraceConsumer
 	TraceProcessorBase
@@ -54,18 +54,24 @@ type MetricsProcessorBase interface {
 	Processor
 }
 
-// MetricsProcessor composes MetricsConsumer with some additional processor-specific functions.
+// MetricsProcessor is a processor that can consume old-style metrics.
 type MetricsProcessorOld interface {
 	consumer.MetricsConsumerOld
 	MetricsProcessorBase
 }
 
-// MetricsProcessor composes MetricsConsumer with some additional processor-specific functions.
+// MetricsProcessor is a processor that can consume metrics.
 type MetricsProcessor interface {
 	consumer.MetricsConsumer
 	MetricsProcessorBase
 }
 
+// LogProcessor is a processor that can consume logs.
+type LogProcessor interface {
+	Processor
+	consumer.LogConsumer
+}
+
 // ProcessorCapabilities describes the capabilities of a Processor.
 type ProcessorCapabilities struct {
 	// MutatesConsumedData is set to true if Consume* function of the
@@ -131,3 +137,18 @@ type ProcessorFactory interface {
 	CreateMetricsProcessor(ctx context.Context, params ProcessorCreateParams,
 		nextConsumer consumer.MetricsConsumer, cfg configmodels.Processor) (MetricsProcessor, error)
 }
+
+// LogProcessorFactory can create LogProcessor.
+type LogProcessorFactory interface {
+	ProcessorFactoryBase
+
+	// CreateLogProcessor creates a processor based on the config.
+	// If the processor type does not support logs or if the config is not valid
+	// error will be returned instead.
+	CreateLogProcessor(
+		ctx context.Context,
+		params ProcessorCreateParams,
+		cfg configmodels.Processor,
+		nextConsumer consumer.LogConsumer,
+	) (LogProcessor, error)
+}

component/receiver.go

@@ -49,6 +49,13 @@ type MetricsReceiver interface {
 	Receiver
 }
 
+// A LogReceiver is a "log data"-to-"internal format" converter.
+// Its purpose is to translate data from the wild into internal data format.
+// LogReceiver feeds a consumer.LogConsumer with data.
+type LogReceiver interface {
+	Receiver
+}
+
 // ReceiverFactoryBase defines the common functions for all receiver factories.
 type ReceiverFactoryBase interface {
 	Factory
@@ -117,3 +124,18 @@ type ReceiverFactory interface {
 	CreateMetricsReceiver(ctx context.Context, params ReceiverCreateParams,
 		cfg configmodels.Receiver, nextConsumer consumer.MetricsConsumer) (MetricsReceiver, error)
 }
+
+// LogReceiverFactory can create a LogReceiver.
+type LogReceiverFactory interface {
+	ReceiverFactoryBase
+
+	// CreateLogReceiver creates a log receiver based on this config.
+	// If the receiver type does not support the data type or if the config is not valid
+	// error will be returned instead.
+	CreateLogReceiver(
+		ctx context.Context,
+		params ReceiverCreateParams,
+		cfg configmodels.Receiver,
+		nextConsumer consumer.LogConsumer,
+	) (LogReceiver, error)
+}

config/config.go

@@ -539,11 +539,11 @@ func loadPipelines(v *viper.Viper) (configmodels.Pipelines, error) {
 		var pipelineCfg configmodels.Pipeline
 
 		// Set the type.
-		switch typeStr {
-		case configmodels.TracesDataTypeStr:
-			pipelineCfg.InputType = configmodels.TracesDataType
-		case configmodels.MetricsDataTypeStr:
-			pipelineCfg.InputType = configmodels.MetricsDataType
+		pipelineCfg.InputType = configmodels.DataType(typeStr)
+		switch pipelineCfg.InputType {
+		case configmodels.TracesDataType:
+		case configmodels.MetricsDataType:
+		case configmodels.LogsDataType:
 		default:
 			return nil, &configError{
 				code: errInvalidPipelineType,

config/config_test.go

@@ -100,7 +100,7 @@ func TestDecodeConfig(t *testing.T) {
 	assert.Equal(t, 1, len(config.Processors), "Incorrect processors count")
 
 	assert.Equal(t,
-		&ExampleProcessor{
+		&ExampleProcessorCfg{
 			ProcessorSettings: configmodels.ProcessorSettings{
 				TypeVal: "exampleprocessor",
 				NameVal: "exampleprocessor",
@@ -258,7 +258,7 @@ func TestSimpleConfig(t *testing.T) {
 		assert.Equalf(t, 1, len(config.Processors), "TEST[%s]", test.name)
 
 		assert.Equalf(t,
-			&ExampleProcessor{
+			&ExampleProcessorCfg{
 				ProcessorSettings: configmodels.ProcessorSettings{
 					TypeVal: "exampleprocessor",
 					NameVal: "exampleprocessor",

config/configmodels/configmodels.go

@@ -78,38 +78,22 @@ type Processor interface {
 type Processors map[string]Processor
 
 // DataType is the data type that is supported for collection. We currently support
-// collecting metrics and traces, this can expand in the future (e.g. logs, events, etc).
-type DataType int
+// collecting metrics, traces and logs, this can expand in the future.
+
+type DataType string
 
 // Currently supported data types. Add new data types here when new types are supported in the future.
 const (
-	_ DataType = iota // skip 0, start types from 1.
-
 	// TracesDataType is the data type tag for traces.
-	TracesDataType
+	TracesDataType DataType = "traces"
 
 	// MetricsDataType is the data type tag for metrics.
-	MetricsDataType
-)
+	MetricsDataType DataType = "metrics"
 
-// Data type strings.
-const (
-	TracesDataTypeStr  = "traces"
-	MetricsDataTypeStr = "metrics"
+	// LogsDataType is the data type tag for logs.
+	LogsDataType DataType = "logs"
 )
 
-// GetString converts data type to string.
-func (dataType DataType) GetString() string {
-	switch dataType {
-	case TracesDataType:
-		return TracesDataTypeStr
-	case MetricsDataType:
-		return MetricsDataTypeStr
-	default:
-		panic("unknown data type")
-	}
-}
-
 // Pipeline defines a single pipeline.
 type Pipeline struct {
 	Name       string   `mapstructure:"-"`