Logs Bridge API prototype

.github/dependabot.yml

@@ -217,6 +217,24 @@ updates:
     schedule:
       interval: weekly
       day: sunday
+  - package-ecosystem: gomod
+    directory: /log
+    labels:
+      - dependencies
+      - go
+      - Skip Changelog
+    schedule:
+      interval: weekly
+      day: sunday
+  - package-ecosystem: gomod
+    directory: /log/internal
+    labels:
+      - dependencies
+      - go
+      - Skip Changelog
+    schedule:
+      interval: weekly
+      day: sunday
   - package-ecosystem: gomod
     directory: /metric
     labels:

log/doc.go

@@ -0,0 +1,85 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+/*
+Package log defines the OpenTelemetry Bridge API.
+It is supposed to be used by a log bridge implementation
+that is an adapter between an existing logging library and OpenTelemetry.
+Application code should not call this API directly.
+
+Existing logging libraries generally provide a much richer set of features
+than in OpenTelemetry. It is not a goal of OpenTelemetry, to ship
+a feature-rich logging library.
+
+# Bridge Implementations
+
+The bridge implementation should allow passing a [context.Context] containing
+a trace context from the caller to [Logger]'s Emit method.
+
+A bridge can use [sync.Pool] of attributes for reducing the number of
+heap allocations.
+
+# API Implementations
+
+This package does not conform to the standard Go versioning policy, all of its
+interfaces may have methods added to them without a package major version bump.
+This non-standard API evolution could surprise an uninformed implementation
+author. They could unknowingly build their implementation in a way that would
+result in a runtime panic for their users that update to the new API.
+
+The API is designed to help inform an instrumentation author about this
+non-standard API evolution. It requires them to choose a default behavior for
+unimplemented interface methods. There are three behavior choices they can
+make:
+
+  - Compilation failure
+  - Panic
+  - Default to another implementation
+
+All interfaces in this API embed a corresponding interface from
+[go.opentelemetry.io/otel/log/embedded]. If an author wants the default
+behavior of their implementations to be a compilation failure, signaling to
+their users they need to update to the latest version of that implementation,
+they need to embed the corresponding interface from
+[go.opentelemetry.io/otel/log/embedded] in their implementation. For
+example,
+
+	import "go.opentelemetry.io/otel/log/embedded"
+
+	type LoggerProvider struct {
+		embedded.LoggerProvider
+		// ...
+	}
+
+If an author wants the default behavior of their implementations to a panic,
+they need to embed the API interface directly.
+
+	import "go.opentelemetry.io/otel/log"
+
+	type LoggerProvider struct {
+		log.LoggerProvider
+		// ...
+	}
+
+This is not a recommended behavior as it could lead to publishing packages that
+contain runtime panics when users update other package that use newer versions
+of [go.opentelemetry.io/otel/log].
+
+Finally, an author can embed another implementation in theirs. The embedded
+implementation will be used for methods not defined by the author. For example,
+an author who wants to default to silently dropping the call can use
+[go.opentelemetry.io/otel/log/noop]:
+
+	import "go.opentelemetry.io/otel/log/noop"
+
+	type LoggerProvider struct {
+		noop.LoggerProvider
+		// ...
+	}
+
+It is strongly recommended that authors only embed
+[go.opentelemetry.io/otel/log/noop] if they choose this default behavior.
+That implementation is the only one OpenTelemetry authors can guarantee will
+fully implement all the API interfaces when a user updates their API.
+*/
+package log // import "go.opentelemetry.io/otel/log"

log/embedded/embedded.go

@@ -0,0 +1,35 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package embedded provides interfaces embedded within
+// the [OpenTelemetry Logs Bridge API].
+//
+// Implementers of the [OpenTelemetry Logs Bridge API] can embed the relevant type
+// from this package into their implementation directly. Doing so will result
+// in a compilation error for users when the [OpenTelemetry Logs Bridge API] is
+// extended (which is something that can happen without a major version bump of
+// the API package).
+//
+// [OpenTelemetry Logs Bridge API]: https://pkg.go.dev/go.opentelemetry.io/otel/log
+package embedded // import "go.opentelemetry.io/otel/log/embedded"
+
+// LoggerProvider is embedded in
+// [go.opentelemetry.io/otel/log.LoggerProvider].
+//
+// Embed this interface in your implementation of the
+// [go.opentelemetry.io/otel/log.LoggerProvider] if you want users to
+// experience a compilation error, signaling they need to update to your latest
+// implementation, when the [go.opentelemetry.io/otel/log.LoggerProvider]
+// interface is extended (which is something that can happen without a major
+// version bump of the API package).
+type LoggerProvider interface{ loggerProvider() }
+
+// Logger is embedded in [go.opentelemetry.io/otel/log.Logger].
+//
+// Embed this interface in your implementation of the
+// [go.opentelemetry.io/otel/log.Logger] if you want users to experience a
+// compilation error, signaling they need to update to your latest
+// implementation, when the [go.opentelemetry.io/otel/log.Logger] interface
+// is extended (which is something that can happen without a major version bump
+// of the API package).
+type Logger interface{ logger() }

log/go.mod

@@ -0,0 +1,20 @@
+module go.opentelemetry.io/otel/log
+
+go 1.20
+
+require (
+	github.com/stretchr/testify v1.8.4
+	go.opentelemetry.io/otel v1.23.0-rc.1
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace go.opentelemetry.io/otel => ../
+
+replace go.opentelemetry.io/otel/trace => ../trace
+
+replace go.opentelemetry.io/otel/metric => ../metric

log/go.sum

@@ -0,0 +1,11 @@
+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/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+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=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=