[chore] Remove use of alias types in service/telemetry (#11182)

This PR moves internal definitions that were aliased publicly to the
public package, and makes sure that hides any other type so that the API
surface is the same.

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>
Co-authored-by: Alex Boten <223565+codeboten@users.noreply.github.com>

service/telemetry/attributes_test.go

@@ -9,7 +9,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/service/telemetry/internal"
 )
 
 func TestAttributes(t *testing.T) {
@@ -50,7 +49,7 @@ func TestAttributes(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			attrs := attributes(internal.Settings{BuildInfo: tt.buildInfo}, tt.cfg)
+			attrs := attributes(Settings{BuildInfo: tt.buildInfo}, tt.cfg)
 			require.Equal(t, tt.wantAttributes, attrs)
 		})
 	}

service/telemetry/factory.go

@@ -16,7 +16,6 @@ import (
 	"go.opentelemetry.io/collector/config/configtelemetry"
 	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/service/internal/resource"
-	"go.opentelemetry.io/collector/service/telemetry/internal"
 )
 
 // disableHighCardinalityMetricsfeatureGate is the feature gate that controls whether the collector should enable
@@ -27,46 +26,46 @@ var disableHighCardinalityMetricsfeatureGate = featuregate.GlobalRegistry().Must
 	featuregate.WithRegisterDescription("controls whether the collector should enable potentially high"+
 		"cardinality metrics. The gate will be removed when the collector allows for view configuration."))
 
-func createDefaultConfig() component.Config {
-	return &Config{
-		Logs: LogsConfig{
-			Level:       zapcore.InfoLevel,
-			Development: false,
-			Encoding:    "console",
-			Sampling: &LogsSamplingConfig{
-				Enabled:    true,
-				Tick:       10 * time.Second,
-				Initial:    10,
-				Thereafter: 100,
-			},
-			OutputPaths:       []string{"stderr"},
-			ErrorOutputPaths:  []string{"stderr"},
-			DisableCaller:     false,
-			DisableStacktrace: false,
-			InitialFields:     map[string]any(nil),
-		},
-		Metrics: MetricsConfig{
-			Level:   configtelemetry.LevelNormal,
-			Address: ":8888",
-		},
-	}
+// Settings holds configuration for building Telemetry.
+type Settings struct {
+	BuildInfo         component.BuildInfo
+	AsyncErrorChannel chan error
+	ZapOptions        []zap.Option
 }
 
-// Factory is a telemetry factory.
-type Factory = internal.Factory
+// Factory is factory interface for telemetry.
+// This interface cannot be directly implemented. Implementations must
+// use the NewFactory to implement it.
+type Factory interface {
+	// CreateDefaultConfig creates the default configuration for the telemetry.
+	// TODO: Should we just inherit from component.Factory?
+	CreateDefaultConfig() component.Config
+
+	// CreateLogger creates a logger.
+	CreateLogger(ctx context.Context, set Settings, cfg component.Config) (*zap.Logger, error)
+
+	// CreateTracerProvider creates a TracerProvider.
+	CreateTracerProvider(ctx context.Context, set Settings, cfg component.Config) (trace.TracerProvider, error)
+
+	// CreateMeterProvider creates a MeterProvider.
+	CreateMeterProvider(ctx context.Context, set Settings, cfg component.Config) (metric.MeterProvider, error)
+
+	// unexportedFactoryFunc is used to prevent external implementations of Factory.
+	unexportedFactoryFunc()
+}
 
 // NewFactory creates a new Factory.
 func NewFactory() Factory {
-	return internal.NewFactory(createDefaultConfig,
-		internal.WithLogger(func(_ context.Context, set Settings, cfg component.Config) (*zap.Logger, error) {
+	return newFactory(createDefaultConfig,
+		withLogger(func(_ context.Context, set Settings, cfg component.Config) (*zap.Logger, error) {
 			c := *cfg.(*Config)
 			return newLogger(c.Logs, set.ZapOptions)
 		}),
-		internal.WithTracerProvider(func(ctx context.Context, set Settings, cfg component.Config) (trace.TracerProvider, error) {
+		withTracerProvider(func(ctx context.Context, set Settings, cfg component.Config) (trace.TracerProvider, error) {
 			c := *cfg.(*Config)
 			return newTracerProvider(ctx, set, c)
 		}),
-		internal.WithMeterProvider(func(_ context.Context, set Settings, cfg component.Config) (metric.MeterProvider, error) {
+		withMeterProvider(func(_ context.Context, set Settings, cfg component.Config) (metric.MeterProvider, error) {
 			c := *cfg.(*Config)
 			disableHighCard := disableHighCardinalityMetricsfeatureGate.IsEnabled()
 			return newMeterProvider(
@@ -80,3 +79,28 @@ func NewFactory() Factory {
 		}),
 	)
 }
+
+func createDefaultConfig() component.Config {
+	return &Config{
+		Logs: LogsConfig{
+			Level:       zapcore.InfoLevel,
+			Development: false,
+			Encoding:    "console",
+			Sampling: &LogsSamplingConfig{
+				Enabled:    true,
+				Tick:       10 * time.Second,
+				Initial:    10,
+				Thereafter: 100,
+			},
+			OutputPaths:       []string{"stderr"},
+			ErrorOutputPaths:  []string{"stderr"},
+			DisableCaller:     false,
+			DisableStacktrace: false,
+			InitialFields:     map[string]any(nil),
+		},
+		Metrics: MetricsConfig{
+			Level:   configtelemetry.LevelNormal,
+			Address: ":8888",
+		},
+	}
+}

service/telemetry/factory_impl.go

@@ -0,0 +1,109 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package telemetry // import "go.opentelemetry.io/collector/service/telemetry"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/metric"
+	metricnoop "go.opentelemetry.io/otel/metric/noop"
+	"go.opentelemetry.io/otel/trace"
+	tracenoop "go.opentelemetry.io/otel/trace/noop"
+	"go.uber.org/zap"
+
+	"go.opentelemetry.io/collector/component"
+)
+
+// factoryOption apply changes to Factory.
+type factoryOption interface {
+	// applyTelemetryFactoryOption applies the option.
+	applyTelemetryFactoryOption(o *factory)
+}
+
+var _ factoryOption = (*factoryOptionFunc)(nil)
+
+// factoryOptionFunc is an factoryOption created through a function.
+type factoryOptionFunc func(*factory)
+
+func (f factoryOptionFunc) applyTelemetryFactoryOption(o *factory) {
+	f(o)
+}
+
+var _ Factory = (*factory)(nil)
+
+// Factory is the implementation of Factory.
+type factory struct {
+	createDefaultConfig component.CreateDefaultConfigFunc
+	createLoggerFunc
+	createTracerProviderFunc
+	createMeterProviderFunc
+}
+
+func (f *factory) CreateDefaultConfig() component.Config {
+	return f.createDefaultConfig()
+}
+
+// createLoggerFunc is the equivalent of Factory.CreateLogger.
+type createLoggerFunc func(context.Context, Settings, component.Config) (*zap.Logger, error)
+
+// withLogger overrides the default no-op logger.
+func withLogger(createLogger createLoggerFunc) factoryOption {
+	return factoryOptionFunc(func(o *factory) {
+		o.createLoggerFunc = createLogger
+	})
+}
+
+func (f *factory) CreateLogger(ctx context.Context, set Settings, cfg component.Config) (*zap.Logger, error) {
+	if f.createLoggerFunc == nil {
+		return zap.NewNop(), nil
+	}
+	return f.createLoggerFunc(ctx, set, cfg)
+}
+
+// createTracerProviderFunc is the equivalent of Factory.CreateTracerProvider.
+type createTracerProviderFunc func(context.Context, Settings, component.Config) (trace.TracerProvider, error)
+
+// withTracerProvider overrides the default no-op tracer provider.
+func withTracerProvider(createTracerProvider createTracerProviderFunc) factoryOption {
+	return factoryOptionFunc(func(o *factory) {
+		o.createTracerProviderFunc = createTracerProvider
+	})
+}
+
+func (f *factory) CreateTracerProvider(ctx context.Context, set Settings, cfg component.Config) (trace.TracerProvider, error) {
+	if f.createTracerProviderFunc == nil {
+		return tracenoop.NewTracerProvider(), nil
+	}
+	return f.createTracerProviderFunc(ctx, set, cfg)
+}
+
+// createMeterProviderFunc is the equivalent of Factory.CreateMeterProvider.
+type createMeterProviderFunc func(context.Context, Settings, component.Config) (metric.MeterProvider, error)
+
+// withMeterProvider overrides the default no-op meter provider.
+func withMeterProvider(createMeterProvider createMeterProviderFunc) factoryOption {
+	return factoryOptionFunc(func(o *factory) {
+		o.createMeterProviderFunc = createMeterProvider
+	})
+}
+
+func (f *factory) CreateMeterProvider(ctx context.Context, set Settings, cfg component.Config) (metric.MeterProvider, error) {
+	if f.createMeterProviderFunc == nil {
+		return metricnoop.NewMeterProvider(), nil
+	}
+	return f.createMeterProviderFunc(ctx, set, cfg)
+}
+
+func (f *factory) unexportedFactoryFunc() {}
+
+// newFactory returns a new Factory.
+func newFactory(createDefaultConfig component.CreateDefaultConfigFunc, options ...factoryOption) Factory {
+	f := &factory{
+		createDefaultConfig: createDefaultConfig,
+	}
+	for _, op := range options {
+		op.applyTelemetryFactoryOption(f)
+	}
+	return f
+}