Wire-debugging Semantic Kernel code talking to OpenAI (and other) LLM APIs through HTTPS

There was this small issue I was running into when trying to move a Semantic Kernel (SK) demo application from an older version to the most recent version 0.16.230615.1-preview.

The code just did not work as before. I did not change anything other than moving to the new code of SK (OF COURSE, I did not… famous last words, eh?).

The result was not an error. It also was not the correct result – rather, it was somehow repeating my question as the Q&A answer.
Something was really weird.

Enter a question or press enter to quit: What is SK?      
🤖:What is SK?
Enter a question or press enter to quit: 
Code language: Bash (bash)

So, what to do now?
Of course, the truth in distributed systems, especially with “REST” APIs, can be found on the wire.

Therefore, I took a debugging proxy to look at which data goes back and forth between my SK-based C# code and the OpenAI API.

As I am working on an Apple MBP, my choice for a debugging proxy is Charles.

I quickly wrote down a custom IWebProxy class and wired it up in my code with an appropriately configured HttpCient:

var httpClient = new HttpClient(new HttpClientHandler { Proxy = new LocalDebuggingProxy() });

var kernel = Kernel.Builder
    .WithOpenAITextEmbeddingGenerationService("text-embedding-ada-002", config["OpenAi:ApiKey"], httpClient: httpClient)
    .WithOpenAITextCompletionService("text-davinci-003", config["OpenAi:ApiKey"], httpClient: httpClient)
    .WithMemoryStorage(store)
    .Build();
Code language: C# (cs)

class LocalDebuggingProxy : IWebProxy
{
    public ICredentials? Credentials { get; set; }

    public Uri? GetProxy(Uri destination)
    {
        return new Uri("http://127.0.0.1:8081");
    }

    public bool IsBypassed(Uri host)
    {
        return false;
    }
}
Code language: C# (cs)

Then, I started the application again and asked the same question… and this is what Charles showed me.

Aha! There we go… now I know where to continue to try to fix my sample.
(And yes, this is simply a bug in SK not properly propagating this kind of error.)

The truth is always on the wire!