Enable static files and configuration file support in YARP integration

[benjaminpetit]

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.

Aspire applications using YARP currently lack built-in support for serving static files. This limits the ability to expose static assets (e.g., HTML, JS, CSS, images) directly through the reverse proxy, which is a common requirement for dashboards, documentation, or lightweight frontends.

While the YARP container itself is capable of serving static files, Aspire does not yet expose a way to configure or enable this behavior within its application model. This creates a gap between what the underlying infrastructure can do and what Aspire makes accessible to developers.

Additionally, we face a related limitation in deployment scenarios: configuration via file is not currently supported. Specifically, WithContainerFiles and BindMount are not usable in deployment, which makes it difficult to provide static content or configuration assets in a portable and production-ready way.

Describe the solution you'd like

• For configuration: we could translate the configuration file as a set of environment variables.
• For static files in general: we need a better support of "container files" or volumes in Aspire

Additional context

No response

[danegsta]

Is there any specific feature for adding a volume or file that you think would be good to have for this scenario that's missing? We've got a number of APIs for adding files to containers, but if there's pain points I'd love to figure out how we can reduce them.

[maddymontaquila]

Related to #11275 ?

[maddymontaquila]

cc @davidfowl

[aromaa]

It would be useful for us if we could define the configuration options for the underlying UseFileServer that is being used for the WithStaticFiles. Specifically, looking for the ServeUnknownFileTypes configuration knob.

See dotnet/yarp#2978.

[davidfowl]

This is a yarp container gap. The yarp container is missing lots of features needed to make it work really well as a static files host.

[aromaa]

What would be the suggested next steps to move this further? I tried to PR a new environment variable to fill in some gaps in the meantime, and was redirected to this issue.