Exporter: WithLogger uses the github.com/go-logr/logr interface to replace the standard library logger

[aniaan]

Problem Statement

Currently otel api and sdk use globalLogger to print logs. globalLogger uses the github.com/go-logr/logr library, which provides the interface, and the specific log implementation can be determined by the user, which is designed to be flexible.

opentelemetry-go/internal/global/internal_logging.go

Lines 30 to 42 in aa868d5

	var globalLogger logr.Logger = stdr.New(log.New(os.Stderr, "", log.LstdFlags|log.Lshortfile))
	var globalLoggerLock = &sync.RWMutex{}
	// SetLogger overrides the globalLogger with l.
	//
	// To see Info messages use a logger with `l.V(1).Enabled() == true`
	// To see Debug messages use a logger with `l.V(5).Enabled() == true`.
	func SetLogger(l logr.Logger) {
	globalLoggerLock.Lock()
	defer globalLoggerLock.Unlock()
	globalLogger = l
	}

But the Exporter uses golang's standard log library, so the printing of logs in a project will be fragmented, which is not conducive to unified log processing and collection.

opentelemetry-go/exporters/zipkin/zipkin.go

Lines 66 to 72 in aa868d5

	// WithLogger configures the exporter to use the passed logger.
	func WithLogger(logger *log.Logger) Option {
	return optionFunc(func(cfg config) config {
	cfg.logger = logger
	return cfg
	})
	}

I have a project where my logging library of choice is zap. When I use the otel api and sdk, I can use github.com/go-logr/zapr to wrap my logger and set the globalLogger, but when I use Exporter, I can't do anything about it, because I can only use golang's standard logging library.

Proposed Solution

Exporter uses the github.com/go-logr/logr library, which is consistent throughout the project

If the community agrees with the proposal, I can submit a PR to resolve the issue

[MrAlias]

The go.opentelemetry.io/otel/exporters/zipkin package is released as stable. That function signature cannot be changed in a backwards compatible way to the proposal.

[MadVikingGod]

I would be open to this addition. We can't remove or change the current WithLogger, but we can add another option and use logr under the hood.

My only real concern is compatibility between logr and the proposed structured logging.