HttpClinetConfig

HttpClinetConfig.cs

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddHttpClient();
builder.Services.AddSingleton<ICertificateProvider, CertificateProvider>();
builder.Services.AddSingleton<IPostConfigureOptions<HttpClientFactoryOptions>, ConfigureHttpClientFactory>();

var app = builder.Build();

var factory = app.Services.GetRequiredService<IHttpClientFactory>();

app.MapGet("/{clientId}", async (string clientId) =>
{
    using var client = factory.CreateClient("cert_" + clientId);
    _ = await client.GetAsync("");
});


await app.StartAsync();


interface ICertificateProvider
{
    X509Certificate2 GetCertificate(string userId);
}

class CertificateProvider : ICertificateProvider
{
    public X509Certificate2 GetCertificate(string userId)
    {
        return new X509Certificate2();
    }
}

class ConfigureHttpClientFactory(ICertificateProvider certificateProvider) : IPostConfigureOptions<HttpClientFactoryOptions>
{
    public void PostConfigure(string? name, HttpClientFactoryOptions options)
    {
        if (name is null)
            return;
        if (!name.StartsWith("cert_"))
            return;


        var userId = name[5..];
        var certificate = certificateProvider.GetCertificate(userId);

        options.HttpMessageHandlerBuilderActions.Add(b =>
        {
            if (b.PrimaryHandler is SocketsHttpHandler handler)
            {
                handler.SslOptions ??= new();
                handler.SslOptions.ClientCertificates = [certificate];
            }
        });
    }
}