fix(cloudtrace): re-add trace logger fields for zap

Commit 0aeada6 accidentally removed
trace field on log statements written with the request logger.

This commit reverts parts of that commit, such that zap request logger
still has the trace field populated.

cloudtrace/middleware.go

@@ -5,6 +5,8 @@ import (
 	"net/http"
 
 	"go.einride.tech/cloudrunner/cloudstream"
+	"go.einride.tech/cloudrunner/cloudzap"
+	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
 )
@@ -34,6 +36,7 @@ func (i *Middleware) GRPCServerUnaryInterceptor(
 	}
 	ctx = i.withOutgoingRequestTracing(ctx, values[0])
 	ctx = i.withInternalContext(ctx, values[0])
+	ctx = i.withLogTracing(ctx, values[0])
 	return handler(ctx, req)
 }
 
@@ -55,6 +58,7 @@ func (i *Middleware) GRPCStreamServerInterceptor(
 	ctx := ss.Context()
 	ctx = i.withOutgoingRequestTracing(ctx, values[0])
 	ctx = i.withInternalContext(ctx, values[0])
+	ctx = i.withLogTracing(ctx, values[0])
 	return handler(srv, cloudstream.NewContextualServerStream(ctx, ss))
 }
 
@@ -69,6 +73,7 @@ func (i *Middleware) HTTPServer(next http.Handler) http.Handler {
 		w.Header().Set(ContextHeader, header)
 		ctx := i.withOutgoingRequestTracing(r.Context(), header)
 		ctx = i.withInternalContext(ctx, header)
+		ctx = i.withLogTracing(ctx, header)
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})
 }
@@ -84,3 +89,22 @@ func (i *Middleware) withInternalContext(ctx context.Context, header string) con
 	}
 	return SetContext(ctx, result)
 }
+
+func (i *Middleware) withLogTracing(ctx context.Context, header string) context.Context {
+	var traceContext Context
+	if err := traceContext.UnmarshalString(header); err != nil {
+		return ctx
+	}
+	if i.TraceHook != nil {
+		ctx = i.TraceHook(ctx, traceContext)
+	}
+	fields := make([]zap.Field, 0, 3)
+	fields = append(fields, cloudzap.Trace(i.ProjectID, traceContext.TraceID))
+	if traceContext.SpanID != "" {
+		fields = append(fields, cloudzap.SpanID(traceContext.SpanID))
+	}
+	if traceContext.Sampled {
+		fields = append(fields, cloudzap.TraceSampled(traceContext.Sampled))
+	}
+	return cloudzap.WithLoggerFields(ctx, fields...)
+}