# ContainerBuildOptionsCallbackAnnotation Properties

- Package: [Aspire.Hosting](/reference/api/csharp/aspire.hosting.md)
- Type: [ContainerBuildOptionsCallbackAnnotation](/reference/api/csharp/aspire.hosting/containerbuildoptionscallbackannotation.md)
- Kind: `Properties`
- Members: `1`

Annotation that provides a callback to configure container build options for a resource.

## Callback

- Name: `Callback`
- Modifiers: `get`
- Returns: `Func<ContainerBuildOptionsCallbackContext, Task>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/bd20f904cde09ecb9c9ae5116a6f13614bf2d7c2/src/Aspire.Hosting/ApplicationModel/ContainerBuildOptionsCallbackAnnotation.cs#L20)

Gets the callback function that will be invoked to configure container build options.

```csharp
public Func<ContainerBuildOptionsCallbackContext, Task> Callback { get; }
```