Single HttpClient with several circuit breaker

[joegoldman2]

I'm using a single HttpClient to perform http calls to several backends with a circuit breaker policy:

builder.Services
    .AddHttpClient("Default")
    .AddResilienceHandler("default", b =>
    {
        b.AddCircuitBreaker(new()
        {
            BreakDuration = TimeSpan.FromSeconds(5),
            FailureRatio = 0.1,
            MinimumThroughput = 100,
            SamplingDuration = TimeSpan.FromSeconds(30),
        });
    });

Is there any way to have a different circuit breaker for each backend that is consumed (depending on the hostname for example)? Or would it be better to create different HttpClient and apply the circuit breaker to each one?

[martincostello]

Without a more complete example of exactly what you're doing, I would have thought that having a different HttpClient for each endpoint with their own circuit breaker would be the easiest way to go about things.

[martintmk]

@joegoldman2

Is there any way to have a different circuit breaker for each backend that is consumed

This will work with a slight modification to your sample:

builder.Services
    .AddHttpClient("Default")
    .AddResilienceHandler("default", b =>
    {
        b.AddCircuitBreaker(new()
        {
            BreakDuration = TimeSpan.FromSeconds(5),
            FailureRatio = 0.1,
            MinimumThroughput = 100,
            SamplingDuration = TimeSpan.FromSeconds(30),
        });
    })
    .SelectPipelineByAuthority();

Notice the use of SelectPipelineByAuthority. This tells the handler to cache the pipeline by authority (scheme + host + port) extracted from request message. Effectively, this assigns a unique instance of pipeline with circuit breaker to each authority and does exactly what you want.

httpClient.GetAsync("https://A"); // creates and caches the pipeline with "https://A" key

httpClient.GetAsync("https://B"); // creates and caches the pipeline with "https://B" key