How to log Polly strategy events and telemetry in .NET applications?

Monitoring when resilience policies trigger—such as retry attempts or open circuit breakers—is crucial for observability in modern cloud applications.

Logging Strategy Events

In Polly v8, strategies expose lifecycle events like OnRetry, OnBreak, and OnTimeout that attach to ILogger.

Code Example

var pipeline = new ResiliencePipelineBuilder()
    .AddRetry(new RetryStrategyOptions
    {
        MaxRetryAttempts = 3,
        Delay = TimeSpan.FromSeconds(1),
        OnRetry = args =>
        {
            Console.WriteLine($"Retry attempt {args.AttemptNumber} after exception: {args.Outcome.Exception?.Message}");
            return ValueTask.CompletedTask;
        }
    })
    .ConfigureTelemetry(new TelemetryOptions
    {
        LoggerFactory = loggerFactory
    })
    .Build();