feat(internallog): add a logging support package

These added packages will be used by our libraries to create loggers
and help create nicely formated log lines in a Cloud Logging format.

v2/internallog/grpclog/grpclog.go

@@ -0,0 +1,88 @@
+// Copyright 2024, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Package grpclog in intended for internal use by generated clients only.
+package grpclog
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"strings"
+
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+)
+
+// ProtoMessageRequest returns a lazily evaluated [slog.LogValuer] for
+// the provided message. The context is used to extract outgoing headers.
+func ProtoMessageRequest(ctx context.Context, msg proto.Message) slog.LogValuer {
+	return &protoMessage{ctx: ctx, msg: msg}
+}
+
+// ProtoMessageResponse returns a lazily evaluated [slog.LogValuer] for
+// the provided message.
+func ProtoMessageResponse(msg proto.Message) slog.LogValuer {
+	return &protoMessage{msg: msg}
+}
+
+type protoMessage struct {
+	ctx context.Context
+	msg proto.Message
+}
+
+func (m *protoMessage) LogValue() slog.Value {
+	if m == nil || m.msg == nil {
+		return slog.Value{}
+	}
+
+	var groupValueAttrs []slog.Attr
+
+	if m.ctx != nil {
+		var headerAttr []slog.Attr
+		if m, ok := metadata.FromOutgoingContext(m.ctx); ok {
+			for k, v := range m {
+				headerAttr = append(headerAttr, slog.String(k, strings.Join(v, ",")))
+			}
+		}
+		if len(headerAttr) > 0 {
+			groupValueAttrs = append(groupValueAttrs, slog.Any("headers", headerAttr))
+		}
+	}
+	mo := protojson.MarshalOptions{AllowPartial: true, UseEnumNumbers: true}
+	if b, err := mo.Marshal(m.msg); err == nil {
+		var m map[string]any
+		if err := json.Unmarshal(b, &m); err == nil {
+			groupValueAttrs = append(groupValueAttrs, slog.Any("payload", m))
+		}
+	}
+
+	return slog.GroupValue(groupValueAttrs...)
+}

v2/internallog/grpclog/grpclog_test.go

@@ -0,0 +1,90 @@
+// Copyright 2024, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//   - Redistributions of source code must retain the above copyright
+//
+// notice, this list of conditions and the following disclaimer.
+//   - Redistributions in binary form must reproduce the above
+//
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//   - Neither the name of Google Inc. nor the names of its
+//
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package grpclog
+
+import (
+	"context"
+	"flag"
+	"log/slog"
+	"os"
+	"testing"
+
+	"github.com/googleapis/gax-go/v2/internallog/internal"
+	"github.com/googleapis/gax-go/v2/internallog/internal/bookpb"
+	"github.com/googleapis/gax-go/v2/internallog/internal/logtest"
+	"google.golang.org/grpc/metadata"
+)
+
+// To update conformance tests in this package run `go test -update_golden`
+func TestMain(m *testing.M) {
+	flag.Parse()
+	os.Exit(m.Run())
+}
+
+func TestLog_protoMessageRequest(t *testing.T) {
+	golden := "request.log"
+	t.Setenv(internal.LoggingLevelEnvVar, "debug")
+	logger, f := setupLogger(t, golden)
+	ctx := metadata.NewOutgoingContext(context.Background(), metadata.Pairs("foo", "bar"))
+	book := &bookpb.Book{
+		Title:  "The book",
+		Author: "The author",
+	}
+	logger.DebugContext(ctx, "msg", "request", ProtoMessageRequest(ctx, book))
+	f.Close()
+	logtest.DiffTest(t, f.Name(), golden)
+}
+
+func TestLog_protoMessageResponse(t *testing.T) {
+	golden := "response.log"
+	t.Setenv(internal.LoggingLevelEnvVar, "debug")
+	logger, f := setupLogger(t, golden)
+	ctx := context.Background()
+	book := &bookpb.Book{
+		Title:  "The book",
+		Author: "The author",
+	}
+	logger.DebugContext(ctx, "msg", "response", ProtoMessageResponse(book))
+	f.Close()
+	logtest.DiffTest(t, f.Name(), golden)
+}
+
+func setupLogger(t *testing.T, golden string) (*slog.Logger, *os.File) {
+	t.Helper()
+	f, err := os.CreateTemp(t.TempDir(), golden)
+	if err != nil {
+		t.Fatal(err)
+	}
+	logger := internal.NewLoggerWithWriter(f)
+	return logger, f
+}

v2/internallog/grpclog/testdata/request.log

@@ -0,0 +1 @@
+{"message":"msg","request":{"headers":{"foo":"bar"},"payload":{"author":"The author","title":"The book"}},"severity":"DEBUG"}

v2/internallog/grpclog/testdata/response.log

@@ -0,0 +1 @@
+{"message":"msg","response":{"payload":{"author":"The author","title":"The book"}},"severity":"DEBUG"}