add handler to all http client (Configuring ALL HttpClients named or unnamed)

Configuring ALL HttpClients named or unnamed

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Http;
using Microsoft.Extensions.Options;
using Polly;
using Prometheus;

var services = new ServiceCollection();

services.AddSingleton<IHttpMessageHandlerBuilderFilter, DefaultHttpMessageHandlerBuilderFilter>();

// added handlers to this client will apply to all http clients
services.AddHttpClient(DefaultHttpMessageHandlerBuilderFilter.GlobalMessageHandlerConfigure)
    .AddTransientHttpErrorPolicy(p => p.WaitAndRetryAsync(3, _ => TimeSpan.FromMilliseconds(60)))
    .AddPolicyHandler(Policy.TimeoutAsync<HttpResponseMessage>(10));

services.AddHttpClient("example", client => client.BaseAddress = new Uri("http://example.com"))
    .UseHttpClientMetrics();

var provider = services.BuildServiceProvider();

var httpClientFactory = provider.GetRequiredService<IHttpClientFactory>();
//http client with Polly Retry + Polly Timeout + Prometheus-net Metrics
var httpClient = httpClientFactory.CreateClient("example");
httpClient.GetAsync("/");

/// <summary>
/// add all handlers of GlobalMessageHandlerConfigure client to all clients
/// https://github.com/dotnet/AspNetCore.Docs/issues/18162
/// </summary>
public class GlobalHttpMessageHandlerBuilderFilter : IHttpMessageHandlerBuilderFilter
{
    public const string GlobalMessageHandlerConfigure = nameof(GlobalMessageHandlerConfigure);

    public Action<HttpMessageHandlerBuilder> Configure(Action<HttpMessageHandlerBuilder> next) =>
        handlerBuilder =>
        {
            next(handlerBuilder);
            
            if (handlerBuilder.Name != GlobalMessageHandlerConfigure)
            {
                var clientFactoryOptions = handlerBuilder.Services
                    .GetRequiredService<IOptionsMonitor<HttpClientFactoryOptions>>().Get(GlobalMessageHandlerConfigure);
                
                if (clientFactoryOptions is not null)
                    foreach (var builderAction in clientFactoryOptions.HttpMessageHandlerBuilderActions)
                        builderAction(handlerBuilder);
            }
        };
}