This library extends IHttpClientBuilder with easy to use resilience policies for the HttpClient.
Dodo.HttpClient.ResiliencePolicies library extends IHttpClientBuilder with easy to use resilience policies for the HttpClient.
In the world of microservices it is quite important to pay attention to resilience of communications between services. You have to think about things like retries, timeouts, circuit breakers, etc. We already have a great library for this class of problems called Polly. It is really powerful. Polly is like a Swiss knife gives you a lot of functionality, but you should know how and when to use it. It could be a complicated task.
Main goal of our library is to hide this complexity from the end-users. It uses Polly under the hood and provides some pre-defined functionality with reasonable defaults and minimal settings to setup resilience policies atop of HttpClient. You can just plug the with single line of code and your HttpClient will become much more robust than before.
Library provides few methods which returns IHttpClientBuilder
and you may chain it with other HttpMessageHandler
.
There are list of public methods to use:
// Pre-defined policies with defaults settings
IHttpClientBuilder AddResiliencePolicies(this IHttpClientBuilder clientBuilder);
// Pre-defined policies with custom settings
IHttpClientBuilder AddResiliencePolicies(this IHttpClientBuilder clientBuilder, ResiliencePoliciesSettings settings)
AddResiliencePolicies
wraps HttpClient with four policies:
Library also provides pre-configured HttpClient:
// Pre-defined HttpClientFactory which is configured to work with `application/json` MIME media type and uses default ResiliencePolicies
IHttpClientBuilder AddJsonClient<TClientInterface, TClientImplementation>(
this IServiceCollection sc,
Uri baseAddress,
string clientName = null)
// Pre-defined HttpClientFactory which is configured to work with `application/json` MIME media type and uses ResiliencePolicies with custom settings
IHttpClientBuilder AddJsonClient<TClientInterface, TClientImplementation>(
this IServiceCollection sc,
Uri baseAddress,
ResiliencePoliciesSettings settings,
string clientName = null)
Custom settings can be provided via ResiliencePoliciesSettings
(see examples below).
Also you may check the defaults provided by the library (all of this can be overriden in custom settings).
Using default client provided by the library and add it to the ServiceCollection
in the Startup like this:
using Dodo.HttpClientResiliencePolicies;
...
service // IServiceCollection
.AddJsonClient(...) // HttpClientFactory to build JsonClient provided by the library with all defaults
Add resilience policies with default settings to existing HttpClient
using Dodo.HttpClientResiliencePolicies;
...
service // IServiceCollection
.AddHttpClient(...) // Existing HttpClientFactory
.AddResiliencePolicies() // Pre-defined resilience policies with all defaults
Define custom settings for resilience policies:
using Dodo.HttpClientResiliencePolicies;
...
var settings = new ResiliencePoliciesSettings
{
OverallTimeout = TimeSpan.FromSeconds(50),
TimeoutPerTry = TimeSpan.FromSeconds(2),
RetryPolicySettings = RetryPolicySettings.Jitter(2, TimeSpan.FromMilliseconds(50)),
CircuitBreakerPolicySettings = new CircuitBreakerPolicySettings(
failureThreshold: 0.5,
minimumThroughput: 10,
durationOfBreak: TimeSpan.FromSeconds(5),
samplingDuration: TimeSpan.FromSeconds(30)
),
OnRetry = (response, time) => { ... }, // Handle retry event. For example you may add logging here
OnBreak = (response, time) => { ... }, // Handle CircuitBreaker break event. For example you may add logging here
OnReset = () => {...}, // Handle CircuitBreaker reset event. For example you may add logging here
OnHalfOpen = () => {...}, // Handle CircuitBreaker reset event. For example you may add logging here
ExtraBreakCondition = BreakConditions.OnTooManyRequests // Extra condition for CircuitBreaker to open (opens on TooManyRequests by default)
}
You may provide only properties which you want to customize, the defaults will be used for the rest.
You may choose different retry strategies. RetryPolicySettings provides static methods to choose Constant, Linear, Exponential or Jitter (exponential with jitter backoff) strategies. Jitter is used as default strategy.
You may provide settings as a parameter to .AddJsonClient(...)
or .AddResiliencePolicies()
to override default settings.