ensure_leading_slash and virtual hosting

[yuzuquats]

I'm following the example in the actix.rs website where web::scope("/") is used. Unfortunately, it seems as though adding a second route is non-trivial because Resource automatically prepends a leading slash:

web::scope("/")
    .guard(guard::Host("www.rust-lang.org"))
    .route("", web::to(|| async { HttpResponse::Ok().body("www") }))
    .route("hello", web::to(|| async { HttpResponse::Ok().body("www") }))       // <--- adding this routes to //hello
    // .route("/hello", web::to(|| async { HttpResponse::Ok().body("www") }))   // <--- alternatively, adding this *also* routes to //hello

This means that in the above example, / and //hello will route. / and /hello will not, however. Important to note, adding the actix_web::middleware::NormalizePath::trim() middleware means hello will be impossible to route to afaik.

I tried a couple of solutions, but i can't think of a great way to create a collection of routes with a shared scope + guard. Couple of options:

1. Guard every route individually

.service(
  web::scope("/").guard(Host("host1.com")).route(...)
)
.service(
  web::scope("/").guard(Host("myhost.com")).route(...)
)
.service(
  web::scope("/hello").guard(Host("host1.com")).route(...)
)

2. guard everything (ie. "") instead of "/"

.service(
  web::scope("").guard(Host("host1.com")).route("/", ...)
)
.service(
  web::scope("").guard(Host("myhost.com")).route("/", ...).route("/hello", ...)
)

3. add a custom middleware that specifically routes "/hello" to "//hello" (like NormalizePath but in reverse?)

None of these options are optimal, so I'm not sure if I'm just missing something obvious. Is there a reason why Resources prepends leading slashes and is it possible to override that behavior?

[robjtede]

The semantics of resource definitions is defined in detail over here: https://docs.rs/actix-web/4.5.1/actix_web/dev/struct.ResourceDef.html#pattern-format-and-matching-behavior

In particular:

This means that pattern string must either be empty or begin with a slash (/).

Therefore this behavior is intentional. The canonical way to avoid double slashes here is to use web::scope(""). This is also documented: https://docs.rs/actix-web/4.5.1/actix_web/struct.Scope.html#avoid-trailing-slashes.

Avoid using trailing slashes in the scope prefix (e.g., web::scope("/scope/")). It will almost certainly not have the expected behavior.