Consider providing an external endpoint resource

[paulomorgado]

For external endpoint resources, I'm using this code:

public class ResourceWithServiceDiscovery : IResourceWithServiceDiscovery
{
    public required string Name { get; init; }

    public required ResourceMetadataCollection Annotations { get; init; }
}

And using it like this:

var remoteResource = new ResourceWithServiceDiscovery
{
    Name = "someremoteresource",
    Annotations = [
        new AllocatedEndpointAnnotation(
            "http",
            ProtocolType.Tcp,
            remoteHubConfig.GetValue<string>("Address")!,
            remoteHubConfig.GetValue<int>("Port"),
            remoteHubConfig.GetValue<string>("Scheme")!)
    ]
};

It would be nice to have something like this built in and showing up in the dashboard.

[paulomorgado]

#2390

[davidfowl]

@paulomorgado if you would like to send a PR for this, that would be great 😄. I think we'd want to model it similarly to how we did AddConnectionString (it's just a parameter). Do you want to mock up an API in the issue?

[paulomorgado]

@davidfowl, AddConnectionString is a preview 4 thing only, right?

And it creates a resource builder behind the scenes, right?

How does that behave if that connection string is added to more than one resource? How would that behave?

[davidfowl]

AddConnectionString adds a parameter resource configured to be accessed like a connection string.

How does that behave if that connection string is added to more than one resource? How would that behave?

It's a resource by itself, it's not added to a resource.

[paulomorgado]

Is this preview 4 only, or can I use it on preview 3?

[davidfowl]

Preview 4

[paulomorgado]

@davidfowl how would adding an external endpoint like AddConnectionString be any different from using

public static IResourceBuilder<TDestination> WithReference<TDestination>(this IResourceBuilder<TDestination> builder, string name, Uri uri)
    where TDestination : IResourceWithEnvironment

[paulomorgado]

@davidfowl, does this look like what you're looking for?

/// <summary>
/// Adds a parameter to the distributed application but wrapped in a resource with a URL for use with <see cref="ResourceBuilderExtensions.WithReference{TDestination}(IResourceBuilder{TDestination}, IResourceBuilder{IResourceWithServiceDiscovery})"/>
/// </summary>
/// <param name="builder">Distributed application builder</param>
/// <param name="name">Name of parameter resource.</param>
/// <param name="uri">The uri of the service.</param>
/// <returns>Resource builder for the parameter.</returns>
/// <exception cref="DistributedApplicationException"></exception>
public static IResourceBuilder<IResourceWithServiceDiscovery> AddEndpoint(this IDistributedApplicationBuilder builder, string name, Uri uri)
{
    if (!uri.IsAbsoluteUri)
    {
        throw new InvalidOperationException("The uri for service reference must be absolute.");
    }

    if (uri.AbsolutePath != "/")
    {
        throw new InvalidOperationException("The uri absolute path must be \"/\".");
    }

    var parameterBuilder = builder.AddParameter(
        name: name,
        callback: uri.ToString,
        secret: false,
        connectionString: false);

    parameterBuilder.WithAnnotation(
        new AllocatedEndpointAnnotation(
            name: "http",
            protocol: ProtocolType.Tcp,
            address: uri.Host,
            port: uri.Port,
            scheme: uri.Scheme));

    var surrogate = new ResourceWithServiceDiscoverySurrogate(parameterBuilder.Resource);
    return builder.CreateResourceBuilder(surrogate);
}

where

internal class ResourceWithServiceDiscoverySurrogate(IResource innerResource) : IResourceWithServiceDiscovery
{
    public string Name => innerResource.Name;

    public ResourceAnnotationCollection Annotations => innerResource.Annotations;
}

It kind of looks odd.

I'd like it to be an EndpointReference, but it doesn't look like a good idea.

[davidfowl]

What's odd?

[paulomorgado]

I'm still trying to wrap my head around it.

Is this what you were suggesting?

[davidfowl]

Without the AllocatedEndpointAnnotation part. I think we would handle this resource type specially in WithReference.