Allow Resources to not be started automatically with the AppHost

[ronbrogan]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

I have various 'accessory' projects in my solution that I would like to start/stop independently of my main API and Frontend services. Currently it seems that if these accessory projects are included in my Aspire AppHost, they're automatically started. I tried setting the initial snapshot state to Waiting, Stopped, Exiting, etc but the project is always started anyhow.

Describe the solution you'd like

It would be great if we could declare that the resource should not be started by default. This could be done via the snapshot state like I was trying, but ideally it should be a bit more straightforward to accomplish. Something that seems decent to me is to have a .WithLifecycle(ResourceLifecycle) extension on the IResourceBuilder that can be used to set how the resource is handled.

public enum ResourceLifecycle
{
    AutoStart,
    DelayStart, // example for other use cases
    ManualStart
}

public static class LifecycleExtensions
{
    public static IResourceBuilder<TResource> WithLifecycle<TResource>(this IResourceBuilder<TResource> builder, ResourceLifecycle lifecycle)
        where TResource: IResource
    {
        return builder.WithAnnotation(new ResourceLifecycleAnnotation(lifecycle));
    }
}

public record class ResourceLifecycleAnnotation(ResourceLifecycle Lifecycle) : IResourceAnnotation { }

// somewhere where the resources are being started
foreach(var exe in allExecutables)
{
    if(exe.TryGetLastAnnotation<ResourceLifecycleAnnotation>(out var lifecycleAnnotation))
    {
        if (lifecycleAnnotation.Lifecycle == ResourceLifecycle.ManualStart)
            continue;

        // etc
    }
}

Additional context

I realize that this can be hacked around with custom commands to run the projects manually, but it seems like a no brainer to me that some things on your dashboard might be optional or scenario dependent - and thus just shouldn't be started automatically.

[KennethHoff]

Related to #5851