Interception of HTTP requests in ksqlDB.RestApi.Client DotNet Authentication

You can use the built in SetBasicAuthCredentials for Basic http authentication (v2.0.0):

string userName = "fred";
string password = "letmein";

var options = new KSqlDbContextOptionsBuilder().UseKSqlDb(@"http:\\localhost:8088")
  .SetBasicAuthCredentials(userName, password)
  .Options;

await using var context = new KSqlDBContext(options);

In order to provide other means for http authentications, override DelegatingHandler.SendAsync in the following way and add it to the http client's constructor:

internal class BearerAuthHandler : DelegatingHandler
{
  public BearerAuthHandler()
  {
    InnerHandler = new HttpClientHandler();
  }
	
  protected override Task<HttpResponseMessage> SendAsync(
    HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
  {
    var token = "xoidiag"; //CreateToken();

    request.Headers.Authorization = new AuthenticationHeaderValue("bearer", token);

    return base.SendAsync(request, cancellationToken);
  }
}

internal class HttpClientFactoryWithBearerAuth : IHttpClientFactory
{
  private readonly Uri uri;

  public HttpClientFactoryWithBearerAuth(Uri uri)
  {
    this.uri = uri ?? throw new ArgumentNullException(nameof(uri));
  }

  public HttpClient CreateClient()
  {
    return new HttpClient(new BearerAuthHandler())
    {
      BaseAddress = uri
    };
  }
}

Override the registration of IHttpClientFactory:

public class KSqlDBContextWithAuth : KSqlDBContext
{
  private readonly KSqlDBContextOptions contextOptions;

  public KSqlDBContextWithAuth(KSqlDBContextOptions contextOptions) 
    : base(contextOptions)
  {
    this.contextOptions = contextOptions ?? throw new ArgumentNullException(nameof(contextOptions));
  }

  protected override void OnConfigureServices(IServiceCollection serviceCollection, KSqlDBContextOptions contextOptions)
  {
    serviceCollection.AddSingleton<IHttpClientFactory, HttpClientFactoryWithBearerAuth>(sp => new HttpClientFactoryWithBearerAuth(new Uri(contextOptions.Url)));

    base.OnConfigureServices(serviceCollection, contextOptions);
  }
}