gRPC for .NET configuration

Configure services options

gRPC services are configured with AddGrpc in Startup.cs. Configuration options are in the Grpc.AspNetCore.Server package.

The following table describes options for configuring gRPC services:

Option Default Value Description
MaxSendMessageSize null The maximum message size in bytes that can be sent from the server. Attempting to send a message that exceeds the configured maximum message size results in an exception. When set to null, the message size is unlimited.
MaxReceiveMessageSize 4 MB The maximum message size in bytes that can be received by the server. If the server receives a message that exceeds this limit, it throws an exception. Increasing this value allows the server to receive larger messages, but can negatively impact memory consumption. When set to null, the message size is unlimited.
EnableDetailedErrors false If true, detailed exception messages are returned to clients when an exception is thrown in a service method. The default is false. Setting EnableDetailedErrors to true can leak sensitive information.
CompressionProviders gzip A collection of compression providers used to compress and decompress messages. Custom compression providers can be created and added to the collection. The default configured providers support gzip compression.
ResponseCompressionAlgorithm null The compression algorithm used to compress messages sent from the server. The algorithm must match a compression provider in CompressionProviders. For the algorithm to compress a response, the client must indicate it supports the algorithm by sending it in the grpc-accept-encoding header.
ResponseCompressionLevel null The compress level used to compress messages sent from the server.
Interceptors None A collection of interceptors that are run with each gRPC call. Interceptors are run in the order they are registered. Globally configured interceptors are run before interceptors configured for a single service.

Interceptors have a per-request lifetime by default. The interceptor constructor is called and parameters are resolved from dependency injection (DI). An interceptor type can also be registered with DI to override how it is created and its lifetime.

Interceptors offer similar functionalities compared to ASP.NET Core middleware. For more information, see gRPC Interceptors vs. Middleware.
IgnoreUnknownServices false If true, calls to unknown services and methods don't return an UNIMPLEMENTED status, and the request passes to the next registered middleware in ASP.NET Core.

Options can be configured for all services by providing an options delegate to the AddGrpc call in Startup.ConfigureServices:

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc(options =>
    {
        options.EnableDetailedErrors = true;
        options.MaxReceiveMessageSize = 2 * 1024 * 1024; // 2 MB
        options.MaxSendMessageSize = 5 * 1024 * 1024; // 5 MB
    });
}

Options for a single service override the global options provided in AddGrpc and can be configured using AddServiceOptions<TService>:

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc().AddServiceOptions<MyService>(options =>
    {
        options.MaxReceiveMessageSize = 2 * 1024 * 1024; // 2 MB
        options.MaxSendMessageSize = 5 * 1024 * 1024; // 5 MB
    });
}

Service interceptors have a per-request lifetime by default. Registering the interceptor type with DI overrides how an interceptor is created and its lifetime.

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc(options =>
    {
        options.Inteceptors.Add<LoggingInterceptor>();
    });
    services.AddSingleton<LoggingInterceptor>();
}

ASP.NET Core server options

Grpc.AspNetCore.Server is hosted by an ASP.NET Core web server. There are a number of options for ASP.NET Core servers, including Kestrel, IIS and HTTP.sys. Each server offers additional options for how HTTP requests are served.

The server used by an ASP.NET Core app is configured in app startup code. The default server is Kestrel.

For more information about the different servers and their configuration options, see:

Configure client options

gRPC client configuration is set on GrpcChannelOptions. Configuration options are in the Grpc.Net.Client package.

The following table describes options for configuring gRPC channels:

Option Default Value Description
HttpHandler New instance The HttpMessageHandler used to make gRPC calls. A client can be set to configure a custom HttpClientHandler or add additional handlers to the HTTP pipeline for gRPC calls. If no HttpMessageHandler is specified, a new HttpClientHandler instance is created for the channel with automatic disposal.
HttpClient null The HttpClient used to make gRPC calls. This setting is an alternative to HttpHandler.
DisposeHttpClient false If set to true and an HttpMessageHandler or HttpClient is specified, then either the HttpHandler or HttpClient, respectively, is disposed when the GrpcChannel is disposed.
LoggerFactory null The LoggerFactory used by the client to log information about gRPC calls. A LoggerFactory instance can be resolved from dependency injection or created using LoggerFactory.Create. For examples of configuring logging, see Logging and diagnostics in gRPC on .NET.
MaxSendMessageSize null The maximum message size in bytes that can be sent from the client. Attempting to send a message that exceeds the configured maximum message size results in an exception. When set to null, the message size is unlimited.
MaxReceiveMessageSize 4 MB The maximum message size in bytes that can be received by the client. If the client receives a message that exceeds this limit, it throws an exception. Increasing this value allows the client to receive larger messages, but can negatively impact memory consumption. When set to null, the message size is unlimited.
Credentials null A ChannelCredentials instance. Credentials are used to add authentication metadata to gRPC calls.
CompressionProviders gzip A collection of compression providers used to compress and decompress messages. Custom compression providers can be created and added to the collection. The default configured providers support gzip compression.
ThrowOperationCanceledOnCancellation false If set to true, clients throw OperationCanceledException when a call is canceled or its deadline is exceeded.
UnsafeUseInsecureChannelCallCredentials false If set to true, CallCredentials are applied to gRPC calls made by an insecure channel. Sending authentication headers over an insecure connection has security implications and shouldn't be done in production environments.
MaxRetryAttempts 5 The maximum retry attempts. This value limits any retry and hedging attempt values specified in the service config. Setting this value alone doesn't enable retries. Retries are enabled in the service config, which can be done using ServiceConfig. A null value removes the maximum retry attempts limit. For more information about retries, see Transient fault handling with gRPC retries.
MaxRetryBufferSize 16 MB The maximum buffer size in bytes that can be used to store sent messages when retrying or hedging calls. If the buffer limit is exceeded, then no more retry attempts are made and all hedging calls but one will be canceled. This limit is applied across all calls made using the channel. A null value removes the maximum retry buffer size limit.
MaxRetryBufferPerCallSize 1 MB The maximum buffer size in bytes that can be used to store sent messages when retrying or hedging calls. If the buffer limit is exceeded, then no more retry attempts are made and all hedging calls but one will be canceled. This limit is applied to one call. A null value removes the maximum retry buffer size limit per call.
ServiceConfig null The service config for a gRPC channel. A service config can be used to configure gRPC retries.

The following code:

  • Sets the maximum send and receive message size on the channel.
  • Creates a client.
static async Task Main(string[] args)
{
    var channel = GrpcChannel.ForAddress("https://localhost:5001", new GrpcChannelOptions
    {
        MaxReceiveMessageSize = 5 * 1024 * 1024, // 5 MB
        MaxSendMessageSize = 2 * 1024 * 1024 // 2 MB
    });
    var client = new Greeter.GreeterClient(channel);

    var reply = await client.SayHelloAsync(
                      new HelloRequest { Name = "GreeterClient" });
    Console.WriteLine("Greeting: " + reply.Message);
}

Note that client interceptors aren't configured with GrpcChannelOptions. Instead, client interceptors are configured using the Intercept extension method with a channel. This extension method is in the Grpc.Core.Interceptors namespace.

static async Task Main(string[] args)
{
    var channel = GrpcChannel.ForAddress("https://localhost:5001");
    var callInvoker = channel.Intercept(new LoggingInterceptor());
    var client = new Greeter.GreeterClient(callInvoker);

    var reply = await client.SayHelloAsync(
                      new HelloRequest { Name = "GreeterClient" });
    Console.WriteLine("Greeting: " + reply.Message);
}

System.Net handler options

Grpc.Net.Client uses a HTTP transport derived from HttpMessageHandler to make HTTP requests. Each handler offers additional options for how HTTP requests are made.

The handler is configured on a channel and can be overridden by setting GrpcChannelOptions.HttpHandler. .NET Core 3 and .NET 5 or later uses SocketsHttpHandler by default. gRPC client apps on .NET Framework should configure WinHttpHandler.

For more information about the different handlers and their configuration options, see:

Warning

ASP.NET Core gRPC has extra requirements for being used with Azure App Service or IIS. For more information on where gRPC can be used, see gRPC on .NET supported platforms.

Additional resources