Polly Retry and Timeout

Intro

Polly v8 implements retry and timeout strategies in .NET resilience pipelines. Retry and Timeout Patterns owns the selection rules; this note owns the concrete HTTP configuration. The example retries a replayable GET, caps total and per-attempt time, adds jitter, and honors server-provided Retry-After delays.

HTTP pipeline

using Microsoft.Extensions.Http.Resilience;
using Polly;
using Polly.Retry;
using Polly.Timeout;
 
builder.Services.AddHttpClient<InventoryClient>(client =>
{
    client.BaseAddress = new Uri("https://inventory.internal/");
    client.Timeout = Timeout.InfiniteTimeSpan;
})
.AddResilienceHandler("inventory", pipeline =>
{
    pipeline.AddTimeout(TimeSpan.FromSeconds(8));
 
    pipeline.AddRetry(new RetryStrategyOptions<HttpResponseMessage>
    {
        MaxRetryAttempts = 3,
        Delay = TimeSpan.FromMilliseconds(200),
        BackoffType = DelayBackoffType.Exponential,
        UseJitter = true,
        ShouldHandle = new PredicateBuilder<HttpResponseMessage>()
            .Handle<HttpRequestException>()
            .Handle<TimeoutRejectedException>()
            .HandleResult(response => response.StatusCode is
                System.Net.HttpStatusCode.RequestTimeout or
                System.Net.HttpStatusCode.TooManyRequests or
                System.Net.HttpStatusCode.BadGateway or
                System.Net.HttpStatusCode.ServiceUnavailable or
                System.Net.HttpStatusCode.GatewayTimeout),
        DelayGenerator = static args =>
        {
            var retryAfter = args.Outcome.Result?.Headers.RetryAfter;
            var delay = retryAfter?.Delta;
 
            if (delay is null && retryAfter?.Date is { } date)
            {
                delay = date - DateTimeOffset.UtcNow;
            }
 
            return ValueTask.FromResult<TimeSpan?>(
                delay > TimeSpan.Zero ? delay : null);
        }
    });
 
    pipeline.AddTimeout(TimeSpan.FromSeconds(2));
});

The outer timeout bounds the whole operation. The inner timeout bounds one attempt. Returning null from DelayGenerator lets Polly use exponential backoff with jitter when the response has no valid Retry-After. The caller’s cancellation token and total deadline still win; do not sleep beyond the remaining request budget.

Apply this policy to methods the dependency actually treats as replayable. A POST needs a server-side idempotency contract whose retention exceeds the retry window.

References

• Polly retry strategy — official RetryStrategyOptions, DelayGenerator, jitter, and outcome handling.
• Polly timeout strategy — official timeout ordering and cancellation behavior.
• .NET HTTP resilience — official HttpClient resilience integration.
• RFC 9110: Retry-After — primary header semantics for date and delay forms.