The easiest and cleanest way to get configurations values in .NET is through the IOptions interface.

Add the following lines of code to your Program.cs

builder.Services
    .AddOptions<OpenAISettings>()
    .BindConfiguration("OpenAI");

Next create a class called OpenAISettings.

public class OpenAISettings
{
    public string Url { get; set; } = string.Empty;
    public string api_key { get; set; } = string.Empty;
}

In your AppSettings.json add the OpenAI section.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "OpenAI": {
    "Url" : "https://openai.com/chat"
    "api_key" : "XXXXXXXXXXXXXXXXXX"
  }
}

That’s it. Now you have access to your configuration settings via the Dependency Injection container. In your controller inject the IOptions interface like this.

public HomeController(IOptions<OpenAISettings> opt)
{
}