Init Logs Bridge API design

.github/dependabot.yml

@@ -217,6 +217,15 @@ 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: /metric
     labels:

docs/design/log-api.md

@@ -0,0 +1,51 @@
+# Logs Bridge API Design
+
+Author: Robert Pająk
+
+Tracking issue at [#4696](https://github.com/open-telemetry/opentelemetry-go/issues/4696).
+
+## Abstract
+
+<!-- A short summary of the proposal. -->
+
+We propose adding a `go.opentelemetry.io/otel/log` Go module which will provide
+[Logs Data Model](https://opentelemetry.io/docs/specs/otel/logs/data-model/)
+and [Logs Bridge API](https://opentelemetry.io/docs/specs/otel/logs/data-model/).
+
+## Background
+
+<!-- An introduction of the necessary background and the problem being solved by the proposed change. -->
+
+They key challenge is to create API which will be complaint with the specification
+and be as performant as possible.
+
+Performance is seen as one of the most imporatant charactristics of logging libraries in Go.
+
+## Proposal
+
+The design and benchmarks takes inspiration from [`slog`](https://pkg.go.dev/log/slog),
+because for the Go team it was also critical to create API that would be fast
+and interoperable with existing logging packages. [^1] [^2]
+
+<!-- A precise statement of the proposed change. -->
+
+## Rationale
+
+<!-- A discussion of alternate approaches and the trade offs, advantages, and disadvantages of the specified approach. -->
+
+## Compatibility
+
+The backwards compatibility is achieved using the `embedded` design pattern
+that is already used in Trace API and Metrics API.
+
+## Implementation
+
+<!-- A description of the steps in the implementation, who will do them, and when. -->
+
+## Open issues (if applicable)
+
+<!-- A discussion of issues relating to this proposal for which the author does not
+know the solution. This section may be omitted if there are none. -->
+
+[^1]: Jonathan Amsterdam, [The Go Blog: Structured Logging with slog](https://go.dev/blog/slog)
+[^2]: Jonathan Amsterdam, [GopherCon Europe 2023: A Fast Structured Logging Package](https://www.youtube.com/watch?v=tC4Jt3i62ns)

log/bench_test.go

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package log_test
+
+import "testing"
+
+// These benchmarks are based on slog/internal/benchmarks.
+// They have the following desirable properties:
+//
+//   - They test a complete log record, from the user's call to its return.
+//
+//   - The benchmarked code is run concurrently in multiple goroutines, to
+//     better simulate a real server (the most common environment for structured
+//     logs).
+//
+//   - Some handlers are optimistic versions of real handlers, doing real-world
+//     tasks as fast as possible (and sometimes faster, in that an
+//     implementation may not be concurrency-safe). This gives us an upper bound
+//     on handler performance, so we can evaluate the (handler-independent) core
+//     activity of the package in an end-to-end context without concern that a
+//     slow handler implementation is skewing the results.
+func BenchmarkEndToEnd(b *testing.B) {
+	// TODO: Replicate https://github.com/golang/go/blob/master/src/log/slog/internal/benchmarks/benchmarks_test.go
+	// Run benchmarks against a "noop.Logger" and "fastTextLogger" (based on fastTextHandler)
+}

log/doc.go

@@ -0,0 +1,5 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package log provides the OpenTelemetry Logs Data Model and Bridge API.
+package log // import "go.opentelemetry.io/otel/log"

log/example_test.go

@@ -0,0 +1,8 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log_test
+
+func Example() {
+	// Output:
+}

log/go.mod

@@ -0,0 +1,3 @@
+module go.opentelemetry.io/otel/log
+
+go 1.20

versions.yaml

@@ -50,3 +50,4 @@ module-sets:
       - go.opentelemetry.io/otel/schema
 excluded-modules:
   - go.opentelemetry.io/otel/internal/tools
+  - go.opentelemetry.io/otel/log