From 9d402178c2ea7189e35d26243aea266c3b1028f4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dawid=20Wysoki=C5=84ski?= <contact@dwysokinski.me>
Date: Thu, 4 May 2023 07:21:19 +0200
Subject: [PATCH] add compression & metadata logging

---
 cmd/client/main.go | 19 +++++++++++++++++--
 cmd/server/main.go | 13 +++++++++++--
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/cmd/client/main.go b/cmd/client/main.go
index 6bc9c43..2f24364 100644
--- a/cmd/client/main.go
+++ b/cmd/client/main.go
@@ -22,6 +22,8 @@ import (
 	"google.golang.org/genproto/googleapis/rpc/errdetails"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/encoding/gzip"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
 
@@ -138,11 +140,24 @@ func newTransportCredentials() (credentials.TransportCredentials, error) {
 func sayHello(ctx context.Context, client proto.GreeterClient, logger *zap.Logger) {
 	name := uuid.NewString()
 	logger.Info("sending request", zap.String("name", name))
-	reply, err := client.SayHello(ctx, &proto.HelloRequest{Name: name})
+	headers := metadata.New(nil)
+	trailer := metadata.New(nil)
+	reply, err := client.SayHello(
+		metadata.NewOutgoingContext(ctx, metadata.Pairs("k1", "v1")),
+		&proto.HelloRequest{Name: name},
+		grpc.UseCompressor(gzip.Name),
+		grpc.Header(&headers),
+		grpc.Trailer(&trailer),
+	)
 	if err != nil {
 		logger.Fatal("something went wrong while calling SayHello", zap.Error(err))
 	}
-	logger.Info("reply received", zap.String("message", reply.GetMessage()))
+	logger.Info(
+		"reply received",
+		zap.String("message", reply.GetMessage()),
+		zap.Any("headers", headers),
+		zap.Any("trailer", trailer),
+	)
 }
 
 func sayHelloToJames(ctx context.Context, client proto.GreeterClient, logger *zap.Logger) {
diff --git a/cmd/server/main.go b/cmd/server/main.go
index f118fb1..0d6bfff 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -23,6 +23,8 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
+	_ "google.golang.org/grpc/encoding/gzip"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
 
@@ -99,7 +101,9 @@ func newServer(address string, logger *zap.Logger) (*server, error) {
 		),
 	)
 
-	proto.RegisterGreeterServer(srv, &greeterServer{})
+	proto.RegisterGreeterServer(srv, &greeterServer{
+		logger: logger,
+	})
 
 	return &server{
 		lis:     lis,
@@ -149,9 +153,14 @@ func createPanicHandler(logger *zap.Logger) grpc_recovery.RecoveryHandlerFunc {
 
 type greeterServer struct {
 	proto.UnimplementedGreeterServer
+	logger *zap.Logger
 }
 
-func (g *greeterServer) SayHello(_ context.Context, r *proto.HelloRequest) (*proto.HelloReply, error) {
+func (g *greeterServer) SayHello(ctx context.Context, r *proto.HelloRequest) (*proto.HelloReply, error) {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if ok {
+		g.logger.Debug("received metadata", zap.Any("metadata", md))
+	}
 	return &proto.HelloReply{
 		Message: buildHelloMsg(r.GetName()),
 	}, nil