Add skeleton of slog bridge (#5292)

* Add slog bridge skeleton

* Apply feedback

Add LoggerProvider as an option.

Rename New to NewHandler.

Add the New function to return an *slog.Logger.

* Rename New to NewLogger

.github/dependabot.yml

@@ -100,6 +100,15 @@ updates:
     schedule:
       interval: weekly
       day: sunday
+  - package-ecosystem: gomod
+    directory: /bridges/otelslog
+    labels:
+      - dependencies
+      - go
+      - Skip Changelog
+    schedule:
+      interval: weekly
+      day: sunday
   - package-ecosystem: gomod
     directory: /bridges/prometheus
     labels:

bridges/otelslog/go.mod

@@ -0,0 +1,16 @@
+module go.opentelemetry.io/contrib/bridges/otelslog
+
+go 1.21
+
+require (
+	go.opentelemetry.io/otel/log v0.0.1-alpha
+	go.opentelemetry.io/otel/sdk v1.24.0
+)
+
+require (
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/metric v1.24.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+)

bridges/otelslog/go.sum

@@ -0,0 +1,25 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
+github.com/go-logr/logr v1.4.1/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+go.opentelemetry.io/otel v1.24.0 h1:0LAOdjNmQeSTzGBzduGe/rU4tZhMwL5rWgtp9Ku5Jfo=
+go.opentelemetry.io/otel v1.24.0/go.mod h1:W7b9Ozg4nkF5tWI5zsXkaKKDjdVjpD4oAt9Qi/MArHo=
+go.opentelemetry.io/otel/log v0.0.1-alpha h1:Gy4SxFnkHv2wmmzv//sblb4/PoCYVtuZbdFY/XamvHM=
+go.opentelemetry.io/otel/log v0.0.1-alpha/go.mod h1:fg1zxLfxAyzlCLyULJTWXUbFVYyOwQZD/DgtGm7VvgA=
+go.opentelemetry.io/otel/metric v1.24.0 h1:6EhoGWWK28x1fbpA4tYTOWBkPefTDQnb8WSGXlc88kI=
+go.opentelemetry.io/otel/metric v1.24.0/go.mod h1:VYhLe1rFfxuTXLgj4CBiyz+9WYBA8pNGJgDcSFRKBco=
+go.opentelemetry.io/otel/sdk v1.24.0 h1:YMPPDNymmQN3ZgczicBY3B6sf9n62Dlj9pWD3ucgoDw=
+go.opentelemetry.io/otel/sdk v1.24.0/go.mod h1:KVrIYw6tEubO9E96HQpcmpTKDVn9gdv35HoYiQWGDFg=
+go.opentelemetry.io/otel/trace v1.24.0 h1:CsKnnL4dUAr/0llH9FKuc698G04IrpWV0MQA/Y1YELI=
+go.opentelemetry.io/otel/trace v1.24.0/go.mod h1:HPc3Xr/cOApsBI154IU0OI0HJexz+aw5uPdbs3UCjNU=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

bridges/otelslog/handler.go

@@ -0,0 +1,112 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package otelslog provides [Handler], an [slog.Handler] implementation, that
+// can be used to bridge between the [log/slog] API and [OpenTelemetry].
+//
+// [OpenTelemetry]: https://opentelemetry.io/docs/concepts/signals/logs/
+package otelslog // import "go.opentelemetry.io/contrib/bridges/otelslog"
+
+import (
+	"context"
+	"log/slog"
+
+	"go.opentelemetry.io/otel/log"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+)
+
+// NewLogger returns a new [slog.Logger] backed by a new [Handler]. See
+// [NewHandler] for details on how the backing Handler is created.
+func NewLogger(options ...Option) *slog.Logger {
+	return slog.New(NewHandler(options...))
+}
+
+type config struct{}
+
+// Option configures a [Handler].
+type Option interface {
+	apply(config) config
+}
+
+type optFunc func(config) config
+
+func (f optFunc) apply(c config) config { return f(c) }
+
+// WithInstrumentationScope returns an [Option] that configures the scope of
+// the [log.Logger] used by a [Handler].
+//
+// By default if this Option is not provided, the Handler will use a default
+// instrumentation scope describing this bridge package. It is recommended to
+// provide this so log data can be associated with its source package or
+// module.
+func WithInstrumentationScope(scope instrumentation.Scope) Option {
+	return optFunc(func(c config) config {
+		// TODO: implement.
+		return c
+	})
+}
+
+// WithLoggerProvider returns an [Option] that configures [log.LoggerProvider]
+// used by a [Handler] to create its [log.Logger].
+//
+// By default if this Option is not provided, the Handler will use the global
+// LoggerProvider.
+func WithLoggerProvider(provider log.LoggerProvider) Option {
+	return optFunc(func(c config) config {
+		// TODO: implement.
+		return c
+	})
+}
+
+// Handler is an [slog.Handler] that sends all logging records it receives to
+// OpenTelemetry.
+type Handler struct {
+	// Ensure forward compatibility by explicitly making this not comparable.
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+
+	// TODO: implement.
+}
+
+// Compile-time check *Handler implements slog.Handler.
+var _ slog.Handler = (*Handler)(nil)
+
+// NewHandler returns a new [Handler] to be used as an [slog.Handler].
+//
+// If [WithLoggerProvider] is not provided, the returned Handler will use the
+// global LoggerProvider.
+//
+// By default the returned Handler will use a [log.Logger] that is identified
+// with this bridge package information. [WithInstrumentationScope] should be
+// used to override this with details about the package or module the handler
+// will instrument.
+func NewHandler(options ...Option) *Handler {
+	// TODO: implement.
+	return &Handler{}
+}
+
+// Handle handles the passed record.
+func (h *Handler) Handle(ctx context.Context, record slog.Record) error {
+	// TODO: implement.
+	return nil
+}
+
+// Enable returns true if the Handler is enabled to log for the provided
+// context and Level. Otherwise, false is returned if it is not enabled.
+func (h *Handler) Enabled(context.Context, slog.Level) bool {
+	// TODO: implement.
+	return true
+}
+
+// WithAttrs returns a new [slog.Handler] based on h that will log using the
+// passed attrs.
+func (h *Handler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	// TODO: implement.
+	return h
+}
+
+// WithGroup returns a new [slog.Handler] based on h that will log all messages
+// and attributes within a group of the provided name.
+func (h *Handler) WithGroup(name string) slog.Handler {
+	// TODO: implement.
+	return h
+}

versions.yaml

@@ -75,6 +75,7 @@ module-sets:
     modules:
       - go.opentelemetry.io/contrib/config
 excluded-modules:
+  - go.opentelemetry.io/contrib/bridges/slog
   - go.opentelemetry.io/contrib/instrgen
   - go.opentelemetry.io/contrib/instrgen/driver
   - go.opentelemetry.io/contrib/instrgen/testdata/interface