Module host 

Host aliases — a host as a name for a mounted controller.

RouterBuilder::host_alias registers them (the hosts block of app_routes! is the declarative form), and the server applies them before routing. A request whose host an alias names is routed as the request for the alias’s target — the aliased mount, then the host’s captured labels — followed by the request’s own path, unless that path lies under one of the alias’s shared mounts, which keep their own paths.

From then on it is that request: Request::path_parts holds the aliased path, so the router, every middleware and the handler see one address, and a middleware that re-derives the matched controller with Router::match_controller gets the one the server dispatched to. An aliased request is identical, apart from Host, to a request any client could send to the aliased path directly: an alias adds addresses, never capabilities.

Structs

HostAliasError

Why RouterBuilder::host_alias refused an alias. The message names the entry and what is wrong with it; app_routes! returns it from the generated init().