feat: add max message size flag for gRPC server configuration (#32)

Introduce a `--max-msg-size` flag to configure the maximum gRPC message size for both receiving and sending. This enhances flexibility and prevents runtime issues with oversized messages by allowing customization through the command line. Defaults to 4MB if unspecified.

Author: tzdybal

cmd/evm-middleware/commands/run.go

@@ -23,6 +23,7 @@ var (
 	genesisHashHex string
 	ethURL         string
 	engineURL      string
+	maxMsgSize     int
 )
 
 func init() {
@@ -35,6 +36,7 @@ func init() {
 	runCmd.Flags().StringVar(&genesisHashHex, "genesis-hash", "0x8bf225d50da44f60dee1c4ee6f810fe5b44723c76ac765654b6692d50459f216", "Genesis hash of the EVM chain")
 	runCmd.Flags().StringVar(&ethURL, "eth-url", "http://127.0.0.1:8545", "URL of the ETH API exposed by EVM node")
 	runCmd.Flags().StringVar(&engineURL, "engine-url", "http://127.0.0.1:8551", "URL of the Engine API exposed by EVM node")
+	runCmd.Flags().IntVar(&maxMsgSize, "max-msg-size", 4*1024*1024, "Maximum message size for gRPC connections (in bytes)") // New flag for maxMsgSize
 
 	// Attach the `runCmd` to the root command
 	rootCmd.AddCommand(runCmd)
@@ -70,7 +72,10 @@ var runCmd = &cobra.Command{
 
 		log.Println("Starting GRPC server...")
 		server := grpcproxy.NewServer(evmClient, grpcproxy.DefaultConfig())
-		s := grpc.NewServer()
+		s := grpc.NewServer(
+			grpc.MaxRecvMsgSize(maxMsgSize), // Use the value from the flag
+			grpc.MaxSendMsgSize(maxMsgSize), // Use the value from the flag
+		)
 		pb.RegisterExecutionServiceServer(s, server)
 
 		wg := sync.WaitGroup{}