PollyGrpc

Polly v8 resilience for gRPC .NET — retry, timeout, and circuit-breaker for any gRPC unary call, plus a built-in GrpcTransientErrors predicate covering the most common transient status codes. Works with any generated gRPC client, GrpcChannel, or CallInvoker.

// Before
var reply = await client.SayHelloAsync(new HelloRequest { Name = "world" });

// After — automatic retry + timeout on every call
var resilient = channel.WithPolly(pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            ShouldHandle = GrpcTransientErrors.IsTransient, // built-in ✔
        })
        .AddTimeout(TimeSpan.FromSeconds(10)));

var reply = await resilient.ExecuteAsync(ct =>
    client.SayHelloAsync(new HelloRequest { Name = "world" }, cancellationToken: ct));

---

Installation

dotnet add package PollyGrpc

Targets net6.0, net8.0, and net9.0. Dependencies: Polly.Core 8.*, Grpc.Net.Client 2.*, Microsoft.Extensions.DependencyInjection.Abstractions 8.*

---

GrpcTransientErrors — the key feature

Knowing which gRPC status codes are safe to retry is the hard part. PollyGrpc ships GrpcTransientErrors.IsTransient so you never have to look them up.

new RetryStrategyOptions
{
    MaxRetryAttempts = 3,
    ShouldHandle = GrpcTransientErrors.IsTransient,
}

Covered status codes

Code	Name	Description
4	DeadlineExceeded	Request timed out before server could respond
8	ResourceExhausted	Quota or rate limit exceeded (like HTTP 429)
10	Aborted	Operation aborted — transaction conflict; safe to retry
14	Unavailable	Server temporarily unavailable — most common transient gRPC error

Tip: StatusCode.Internal (13) can also be transient (connection reset). If you see it in logs, extend the predicate:

var myErrors = GrpcTransientErrors.StatusCodes.ToHashSet();
myErrors.Add(StatusCode.Internal);

new RetryStrategyOptions
{
    ShouldHandle = new PredicateBuilder()
        .Handle<RpcException>(ex => myErrors.Contains(ex.StatusCode))
}

---

Quick start

Approach 1 — ResilientGrpcChannel (simplest)

Wrap your existing GrpcChannel and pass any lambda that makes a gRPC call:

using PollyGrpc;

var channel  = GrpcChannel.ForAddress("https://my-service:5001");
var resilient = channel.WithPolly(pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            Delay = TimeSpan.FromMilliseconds(200),
            BackoffType = DelayBackoffType.Exponential,
            UseJitter = true,
            ShouldHandle = GrpcTransientErrors.IsTransient,
        })
        .AddTimeout(TimeSpan.FromSeconds(10)));

var client = new Greeter.GreeterClient(channel);

// Unary call — pass AsyncUnaryCall directly
var reply = await resilient.ExecuteAsync(ct =>
    client.SayHelloAsync(new HelloRequest { Name = "world" }, cancellationToken: ct));

// Or pass .ResponseAsync explicitly
var reply2 = await resilient.ExecuteAsync(ct =>
    client.SayHelloAsync(new HelloRequest { Name = "world" }, cancellationToken: ct).ResponseAsync);

Approach 2 — PollyClientInterceptor (for typed clients)

The interceptor approach integrates transparently at the gRPC channel level — no changes to call sites needed:

var options = new PollyGrpcOptions
{
    MaxRetries = 3,
    BaseDelay  = TimeSpan.FromMilliseconds(200),
    CallTimeout = TimeSpan.FromSeconds(10),
    TransientStatusCodes = GrpcTransientErrors.StatusCodes.ToHashSet(),
};

var channel = GrpcChannel.ForAddress("https://my-service:5001",
    new GrpcChannelOptions
    {
        Interceptors = { new PollyClientInterceptor(options) }
    });

// All calls through this channel are automatically protected
var client = new Greeter.GreeterClient(channel);
var reply  = await client.SayHelloAsync(new HelloRequest { Name = "world" });

Approach 3 — Dependency injection

// Program.cs
builder.Services.AddPollyGrpc("https://my-service:5001", pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            Delay = TimeSpan.FromMilliseconds(200),
            BackoffType = DelayBackoffType.Exponential,
            UseJitter = true,
            ShouldHandle = GrpcTransientErrors.IsTransient,
        })
        .AddTimeout(TimeSpan.FromSeconds(10))
        .AddCircuitBreaker(new CircuitBreakerStrategyOptions
        {
            FailureRatio = 0.5,
            MinimumThroughput = 10,
            SamplingDuration = TimeSpan.FromSeconds(30),
            BreakDuration = TimeSpan.FromSeconds(15),
        }));

// Service
public class GreeterService(ResilientGrpcChannel resilient, GrpcChannel channel)
{
    private readonly Greeter.GreeterClient _client = new(channel);

    public Task<HelloReply> SayHelloAsync(string name, CancellationToken ct = default) =>
        resilient.ExecuteAsync(token =>
            _client.SayHelloAsync(new HelloRequest { Name = name }, cancellationToken: token), ct);
}

---

ResilientGrpcChannel methods

Method	Description
ExecuteAsync<T>(Func<CancellationToken, AsyncUnaryCall<T>>)	Unary call — automatically disposes the call handle
ExecuteAsync<T>(Func<CancellationToken, Task<T>>)	Any async operation returning T
ExecuteAsync(Func<CancellationToken, Task>)	Any async operation with no return value

---

Pipeline order

[Timeout] → [Retry] → [Circuit Breaker] → [gRPC server]

pipeline
    .AddTimeout(TimeSpan.FromSeconds(10))   // 1. Per-attempt deadline
    .AddRetry(retryOptions)                 // 2. Retry transient failures
    .AddCircuitBreaker(cbOptions)           // 3. Open circuit under load

---

Related Packages

Package	Downloads	Description
PollyHealthChecks		ASP.NET Core health checks for Polly v8 circuit breakers — expose circuit-breaker state (Closed, HalfOpen, Open, Isolated) as /health endpoint responses
PollyBackoff		Backoff delay strategies for Polly v8 resilience pipelines
PollyEFCore		Polly v8 resilience pipelines for Entity Framework Core — wrap every EF Core query and SaveChanges with retry, timeout and circuit-breaker via a single AddPollyResilience() call
PollyRabbitMQ		Polly v8 resilience for RabbitMQ.Client v7+ — retry, circuit-breaker, and timeout for IChannel operations, with built-in RabbitMqTransientErrors predicate covering AlreadyClosedException, BrokerUnreachableException, OperationInterruptedException, and ConnectFailureException
PollyMailKit		Polly v8 resilience pipelines for MailKit — retry, timeout, and circuit-breaker for SmtpClient.SendAsync and any MailKit SMTP operation
PollyMassTransit		Polly v8 resilience pipelines for MassTransit — retry, timeout, and circuit-breaker for IBus.Publish and ISendEndpointProvider.Send
PollyNpgsql		Polly v8 resilience pipelines for Npgsql (PostgreSQL) — retry, timeout, and circuit-breaker for NpgsqlConnection queries and commands, plus a built-in PostgresTransientErrors predicate covering all common PostgreSQL transient SQLSTATE codes
PollyOpenAI		Polly v8 resilience for OpenAI and Azure OpenAI API calls
PollyAzureEventHub		Polly v8 resilience pipelines for Azure Event Hubs — retry, timeout, and circuit-breaker for EventHubProducerClient and EventHubConsumerClient
PollyElasticsearch		Polly v8 resilience pipelines for Elastic.Clients.Elasticsearch 8+ — retry, timeout, and circuit-breaker for any Elasticsearch operation, plus a built-in ElasticTransientErrors predicate covering rate limiting (429), service unavailability (503), gateway timeouts (504), and connection failures
PollyHangfire		Polly v8 resilience pipelines for Hangfire — retry, timeout, and circuit-breaker for IBackgroundJobClient.Enqueue and Schedule
PollyCosmosDb		Polly v8 resilience pipelines for Azure Cosmos DB — retry, timeout, and circuit-breaker for Container operations, plus a built-in CosmosTransientErrors predicate covering rate limiting (429), timeouts (408), partition failovers (410), and service unavailability (503)
PollySendGrid		Polly v8 resilience pipelines for SendGrid — retry, timeout, and circuit-breaker for ISendGridClient.SendEmailAsync
PollyMongo		Polly v8 resilience pipelines for MongoDB.Driver — wrap Find, InsertOne, UpdateOne, DeleteOne and other IMongoCollection calls with retry, timeout, circuit-breaker, and more using a single ResilientMongoCollection decorator
PollyDapper		Polly v8 resilience pipelines for Dapper — wrap QueryAsync, ExecuteAsync, and other Dapper calls with retry, timeout, circuit-breaker, and more using a single ResilientDbConnection decorator
PollyMediatR		Polly v8 resilience pipelines for MediatR — add retry, timeout, circuit-breaker, rate-limiting, hedging, and chaos engineering to any MediatR request handler with a single line of DI registration
PollySqlClient		Polly v8 resilience pipelines for Microsoft.Data.SqlClient (SQL Server and Azure SQL) — retry, timeout, and circuit-breaker for SqlConnection queries and commands, plus a built-in SqlServerTransientErrors predicate covering all common SQL Server and Azure SQL transient error numbers
PollyAzureKeyVault		Polly v8 resilience pipelines for Azure Key Vault — retry, timeout, and circuit-breaker for SecretClient, KeyClient, and CertificateClient
PollyAzureQueueStorage		Polly v8 resilience pipelines for Azure Queue Storage — retry, timeout, and circuit-breaker for Azure.Storage.Queues QueueClient
PollyRedis		Polly v8 resilience for StackExchange.Redis
PollyAzureServiceBus		Polly v8 resilience for Azure Service Bus — retry, circuit breaker, and timeout for sending and receiving messages
PollyAzureBlob		Polly v8 resilience pipelines for Azure Blob Storage — wrap BlobClient and BlobContainerClient operations with retry, timeout, circuit-breaker, and more using ResilientBlobClient and ResilientBlobContainerClient decorators
PollyAzureTableStorage		Polly v8 resilience pipelines for Azure Table Storage — retry, timeout, and circuit-breaker for Azure.Data.Tables TableClient

💼 Need .NET consulting?

The author of this package is available for consulting on Polly v8 resilience, Azure cloud architecture, and clean .NET design.

→ solidqualitysolutions.com · LinkedIn

License

MIT