Use serviceContext when starting

[asimpson]

dskit/modules/module_service.go

Line 83 in fb7d1aa

err := w.service.StartAsync(context.Background())

Using context.Background() creates an empty context when starting which can cause non-obvious behavior. For example, if your service is using logging.FromContext(ctx) this will result in issues like: no logger was found in the context, so using NopLogger. Ideally dskit should use the passed in serviceContext here instead of making a new context.

[pstibrany]

Ideally dskit should use the passed in serviceContext here instead of making a new context.

That would not work for reason stated in the code. However we could use context.WithoutCancel(serviceContext) so that other context properties are available.