Feature Overview (aka. Goal Summary)

Provide a way for users to add custom middleware functions to the Developer Hub backend when initializing the root HttpRouter.

While it's possible to inject the rootHttpRouter service and add paths in a dynamic plugin, it's not possible to install interceptors for cross-cutting concerns without providing code in the backend to create a custom HTTP router service factory. When there's no code access to modify the backend as in Developer Hub, this isn't possible.

This feature is about providing an extension point or other means to allow a dynamic plugin to contribute additional custom middleware functions to the backend's root HTTP router.

Goals (aka. expected user outcomes)

• help users that are migrating from an upstream Backstage installation to Developer Hub that may have had to introduce custom middleware

Requirements (aka. Acceptance Criteria):

• There is an example dynamic plugin that demonstrates the functionality
• A user can create a simple generic middleware interceptor function and install it via a dynamic plugin
• A user can create a Proxy Header Factory middleware interceptor function and install it via a dynamic plugin

Documentation Considerations