Polly for .NET: Building Resilient Applications

Polly provides resilience patterns for .NET – retry, circuit breaker, timeout, fallback. Essential for microservices.

Installation

dotnet add package Polly

Retry Policy

var retryPolicy = Policy
    .Handle<HttpRequestException>()
    .WaitAndRetryAsync(3, attempt => TimeSpan.FromSeconds(Math.Pow(2, attempt)));

var result = await retryPolicy.ExecuteAsync(() => httpClient.GetAsync(url));

Circuit Breaker

var circuitBreaker = Policy
    .Handle<Exception>()
    .CircuitBreakerAsync(
        exceptionsAllowedBeforeBreaking: 5,
        durationOfBreak: TimeSpan.FromMinutes(1));

With HttpClientFactory

services.AddHttpClient<MyService>()
    .AddTransientHttpErrorPolicy(p => 
        p.WaitAndRetryAsync(3, _ => TimeSpan.FromSeconds(1)));

References

• Polly GitHub