IHttpClientFactory with Polly

Polly is a .NET resilience and transient-fault-handling library that allows developers to express policies such as Retry, Circuit Breaker, Timeout, Bulkhead Isolation, and Fallback in a fluent and thread-safe manner.

Example

In this example

IHttpClientFactory is used for:

1. configuration of HttpClients,
2. setting the Bearer token if available
3. ignoring ssl validation errors for self signed certificates

Polly is used for:

1. setting the timeout policy
2. retry 5 times by defining how long to wait before each retry
3. setting cirbuitbreaker is activated after 6 exceptions and duration of break is 30 seconds.

Startup.cs

services.AddHttpClient("Default", x =>
                {
					//Setting bearer token
                    x.SetBearerToken(ServiceInfo.AccessToken);
                    x.DefaultRequestHeaders.Add("Accept", "application/json");
                })
                .ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler
                {
					//skip validation for ssl cets (self signed) - NOT FOR PRODUCTION
                    ServerCertificateCustomValidationCallback =
                        (httpRequestMessage, cert, cetChain, policyErrors) => true
                })
				//Setting timout policy
                .AddPolicyHandler(Policy.TimeoutAsync<HttpResponseMessage>(180))
				//5 retries
                .AddTransientHttpErrorPolicy(builder =>
                    builder.WaitAndRetryAsync(new[]
                        {
                            TimeSpan.FromSeconds(1),
                            TimeSpan.FromSeconds(5),
                            TimeSpan.FromSeconds(10),
                            TimeSpan.FromSeconds(15),
                            TimeSpan.FromSeconds(20)
                        },
                        onRetry: (result, span, retryCount, ctx)
                            => Log.Warning($"{DateTime.Now}:The request failed.Retrying attempt :({retryCount})")))
				//CircuitBreaked to be activated after 5 exceptions and is active for 30 secs
                .AddTransientHttpErrorPolicy(builder => builder.CircuitBreakerAsync(6, TimeSpan.FromSeconds(30),
                    onBreak: (result, span, ctx) =>

                        Log.Warning($"{DateTime.Now}:The circuitBreaker is activated"),
					//resetting the circuibreaker
                    onReset: delegate (Context context) { Log.Warning("The circuitBreaker is reset"); })
                );