feat(cloudslog): bridge log/slog with cloudzap

A new empty package is added: cloudslog that is intended to contain
handler(s) and funtions related to the new std lib slog package.

This change also replaces the default log/slog logger to a one that
instead logs to our default zap logger. This is useful if you use libs
or sdks that do not rely on cloudrunner and/or zap.

cloudslog/doc.go

@@ -0,0 +1,2 @@
+// Package cloudslog provides primitives for structured logging with the standard library log/slog package.
+package cloudslog

go.mod

@@ -24,6 +24,7 @@ require (
 	go.opentelemetry.io/otel/sdk v1.19.0
 	go.opentelemetry.io/otel/sdk/metric v1.19.0
 	go.uber.org/zap v1.26.0
+	go.uber.org/zap/exp v0.2.0
 	golang.org/x/oauth2 v0.13.0
 	golang.org/x/sync v0.4.0
 	google.golang.org/api v0.147.0

go.sum

@@ -167,6 +167,8 @@ go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
 go.uber.org/multierr v1.10.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 go.uber.org/zap v1.26.0 h1:sI7k6L95XOKS281NhVKOFCUNIvv9e0w4BF8N3u+tCRo=
 go.uber.org/zap v1.26.0/go.mod h1:dtElttAiwGvoJ/vj4IwHBS/gXsEu/pZ50mUIRWuG0so=
+go.uber.org/zap/exp v0.2.0 h1:FtGenNNeCATRB3CmB/yEUnjEFeJWpB/pMcy7e2bKPYs=
+go.uber.org/zap/exp v0.2.0/go.mod h1:t0gqAIdh1MfKv9EwN/dLwfZnJxe9ITAZN78HEWPFWDQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=

run.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"flag"
 	"fmt"
+	"log/slog"
 	"os"
 	"os/signal"
 	"runtime/debug"
@@ -21,6 +22,7 @@ import (
 	"go.einride.tech/cloudrunner/cloudzap"
 	"go.einride.tech/protobuf-sensitive/protosensitive"
 	"go.uber.org/zap"
+	"go.uber.org/zap/exp/zapslog"
 	"go.uber.org/zap/zapcore"
 	"google.golang.org/grpc"
 )
@@ -103,6 +105,8 @@ func Run(fn func(context.Context) error, options ...Option) (err error) {
 	if err != nil {
 		return fmt.Errorf("cloudrunner.Run: %w", err)
 	}
+	// Set the global default log/slog logger to write to our zap logger
+	slog.SetDefault(newSlogger(logger))
 	run.loggerMiddleware.Logger = logger
 	ctx = cloudzap.WithLogger(ctx, logger)
 	if err := cloudprofiler.Start(run.config.Profiler); err != nil {
@@ -196,3 +200,13 @@ func (b buildSettingsMarshaler) MarshalLogObject(encoder zapcore.ObjectEncoder)
 	}
 	return nil
 }
+
+// newSlogger returns a slog logger in which the underlying handler writes to the given zap logger.
+// this func is kept here instead of in the cloudslog package to avoid having a api surface
+// that encompasses zap in that package.
+func newSlogger(zl *zap.Logger) *slog.Logger {
+	slogHandler := zapslog.NewHandler(zl.Core(), &zapslog.HandlerOptions{
+		AddSource: true, // same as zap's AddCaller
+	})
+	return slog.New(slogHandler)
+}