How to get the registered object in DI after kernel.Clone()

[futugyou]

//DI
var kernelBuilder = services.AddKernel();
services.AddSingleton<IEmailService, EmailService>();
kernelBuilder.Plugins.AddFromType<EmailPlugin>()

// plugin
public class EmailPlugin
{
    public EmailPlugin(IEmailService emailService){}
}

// send email service
public interface IEmailService{}
public class EmailService : IEmailService{}

// sk service
public SKService(Kernel kernel)
{
        _kernel = kernel;
}
public async Task<string[]> EmailSender()
{
        // _kernel = _kernel.Clone();
        // _kernel.Plugins.Clear();
        // _kernel.Plugins.AddFromType<EmailPlugin>("EmailPlugin");

 ....
        var result = _chatCompletionService.GetStreamingChatMessageContentsAsync(
            chatMessages,
            executionSettings: openAIPromptExecutionSettings,
            kernel: _kernel);
...
}

The above code throws an error after uncommenting the code.
System.InvalidOperationException: Unable to resolve service for type 'IEmailService' while attempting to activate 'EmailPlugin'
How can I get the object after kernel.Clone()?
I tried kernelBuilder.Services.AddSingleton<IEmailService, EmailService>();, but it didn't solve the problem.

[runceel]

Here's a potential workaround:

_kernel = _kernel.Clone();
_kernel.Plugins.Clear();
_kernel.Plugins.AddFromType<EmailPlugin>("EmailPlugin", _kernel.Services);

The Plugins property is essentially a collection of KernelPlugin instances. The key is to explicitly pass the services when adding the plugin. By passing _kernel.Services as the second parameter, the plugin is instantiated using the services registered in the cloned kernel's DI container, enabling the EmailPlugin to properly resolve its IEmailService dependency.

[futugyou]

@runceel
Thank you for your reply — it solved my problem and also made me realize that kernel.Plugins and kernelBuilder.Plugins refer to different objects.

After looking into it, I found that not only can we write _kernel.Plugins.AddFromType<EmailPlugin>("EmailPlugin", _kernel.Services), but we can also write _kernel.ImportPluginFromType<EmailPlugin>("EmailPlugin"). Both approaches achieve the same goal: passing the serviceProvider when calling KernelPluginFactory.CreateFromType<T>(pluginName, serviceProvider).

Thanks again for your helpful response!