otelcol: add telemetry.Factory to Factories (#13950)

#### Description

Add a `TelemetryFactory telemetry.Factory` field to `otelcol.Factories`.
If it is nil, it will default to an `otelconftelemetry` factory.

This enables overriding telemetry providers.

#### Link to tracking issue

Fixes #4970

#### Testing

- Ran the collector without any telemetry config, verified that logging
still works as expected
- Ran the collector with standard (otelconftelemetry) config, verified
it is used as expected (I just smoke tested by enabling debug logging --
more comprehensive unit tests exist)
- Ran a modified version of the collector with a custom telemetry
factory

#### Documentation

N/A

Author: axw

.chloggen/otelcol-telemetryfactory.yaml

@@ -0,0 +1,28 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: pkg/otelcol
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Require a telemetry factory to be injected through otelcol.Factories
+
+# One or more tracking issues or pull requests related to the change
+issues: [4970]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  otelcol.Factories now has a required Telemetry field,
+  which contains the telemetry factory to be used by the service.
+  Set it to otelconftelemetry.NewFactory() for the existing behavior.
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

cmd/builder/internal/builder/templates/components.go.tmpl

@@ -10,6 +10,7 @@ import (
 	"go.opentelemetry.io/collector/otelcol"
 	"go.opentelemetry.io/collector/processor"
 	"go.opentelemetry.io/collector/receiver"
+	"go.opentelemetry.io/collector/service/telemetry/otelconftelemetry"
 	{{- range .Connectors}}
 	{{.Name}} "{{.Import}}"
 	{{- end}}
@@ -29,7 +30,9 @@ import (
 
 func components() (otelcol.Factories, error) {
 	var err error
-	factories := otelcol.Factories{}
+	factories := otelcol.Factories{
+		Telemetry: otelconftelemetry.NewFactory(),
+	}
 
 	factories.Extensions, err = otelcol.MakeFactoryMap[extension.Factory](
 		{{- range .Extensions}}

cmd/otelcorecol/components.go

@@ -31,6 +31,7 @@ require (
 	go.opentelemetry.io/collector/receiver v1.44.0
 	go.opentelemetry.io/collector/receiver/nopreceiver v0.138.0
 	go.opentelemetry.io/collector/receiver/otlpreceiver v0.138.0
+	go.opentelemetry.io/collector/service v0.138.0
 	golang.org/x/sys v0.36.0
 )
 
@@ -135,7 +136,6 @@ require (
 	go.opentelemetry.io/collector/receiver/receiverhelper v0.138.0 // indirect
 	go.opentelemetry.io/collector/receiver/receivertest v0.138.0 // indirect
 	go.opentelemetry.io/collector/receiver/xreceiver v0.138.0 // indirect
-	go.opentelemetry.io/collector/service v0.138.0 // indirect
 	go.opentelemetry.io/collector/service/hostcapabilities v0.138.0 // indirect
 	go.opentelemetry.io/contrib/bridges/otelzap v0.13.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.63.0 // indirect

cmd/otelcorecol/go.mod

@@ -36,6 +36,7 @@ import (
 	"go.opentelemetry.io/collector/processor/batchprocessor"
 	"go.opentelemetry.io/collector/receiver"
 	"go.opentelemetry.io/collector/receiver/otlpreceiver"
+	"go.opentelemetry.io/collector/service/telemetry/otelconftelemetry"
 )
 
 func assertMetrics(t *testing.T, metricsAddr string, expectedMetrics map[string]bool) bool {
@@ -204,6 +205,7 @@ func testMetricStability(t *testing.T, configFile string, expectedMetrics map[st
 				Receivers:  map[component.Type]receiver.Factory{otlpreceiver.NewFactory().Type(): otlpreceiver.NewFactory()},
 				Processors: map[component.Type]processor.Factory{batchprocessor.NewFactory().Type(): batchprocessor.NewFactory()},
 				Exporters:  map[component.Type]exporter.Factory{debugexporter.NewFactory().Type(): debugexporter.NewFactory()},
+				Telemetry:  otelconftelemetry.NewFactory(),
 			}, nil
 		},
 		ConfigProviderSettings: otelcol.ConfigProviderSettings{

internal/e2e/metric_stability_test.go

@@ -54,7 +54,8 @@ func (s State) String() string {
 
 // CollectorSettings holds configuration for creating a new Collector.
 type CollectorSettings struct {
-	// Factories service factories.
+	// Factories returns component factories for the collector.
+	//
 	// TODO(13263) This is a dangerous "bare" function value, should define an interface
 	// following style guidelines.
 	Factories func() (Factories, error)
@@ -178,6 +179,10 @@ func (col *Collector) setupConfigurationComponents(ctx context.Context) error {
 	if err != nil {
 		return fmt.Errorf("failed to initialize factories: %w", err)
 	}
+	if factories.Telemetry == nil {
+		factories.Telemetry = otelconftelemetry.NewFactory()
+	}
+
 	cfg, err := col.configProvider.Get(ctx, factories)
 	if err != nil {
 		return fmt.Errorf("failed to get config: %w", err)
@@ -219,10 +224,7 @@ func (col *Collector) setupConfigurationComponents(ctx context.Context) error {
 		},
 		AsyncErrorChannel: col.asyncErrorChannel,
 		LoggingOptions:    col.set.LoggingOptions,
-
-		// TODO: inject the telemetry factory through factories.
-		// See https://github.com/open-telemetry/opentelemetry-collector/issues/4970
-		TelemetryFactory: otelconftelemetry.NewFactory(),
+		TelemetryFactory:  factories.Telemetry,
 	}, cfg.Service)
 	if err != nil {
 		return err
@@ -272,6 +274,10 @@ func (col *Collector) DryRun(ctx context.Context) error {
 	if err != nil {
 		return fmt.Errorf("failed to initialize factories: %w", err)
 	}
+	if factories.Telemetry == nil {
+		factories.Telemetry = otelconftelemetry.NewFactory()
+	}
+
 	cfg, err := col.configProvider.Get(ctx, factories)
 	if err != nil {
 		return fmt.Errorf("failed to get config: %w", err)
@@ -291,6 +297,7 @@ func (col *Collector) DryRun(ctx context.Context) error {
 		ExportersFactories:  factories.Exporters,
 		ConnectorsConfigs:   cfg.Connectors,
 		ConnectorsFactories: factories.Connectors,
+		TelemetryFactory:    factories.Telemetry,
 	}, service.Config{
 		Pipelines: cfg.Service.Pipelines,
 	})