Discovered while working on something else that we didn't properly
handle this:
```rust
let one = Router::new().route("/", get(|| async {}));
let two = Router::new().route("/", post(|| async {}));
let app = one.merge(two);
```
This introduces two new possible panics when constructing routers:
- If merging two routers that each have a fallback. Previously that left
side fallback would be silently discarded.
- If nesting a router that has a fallback. Previously it would be
silently discarded.
Overall this should make things more explicit and users shouldn't have
to worry "why isn't my fallback" working.
Fixes#488
* Empty crate
* basic setup
* Support `HEAD`
* Add remaining methods
* Impl Debug
* Add `MethodRouter::merge`
* WIP
* Support same route with different methods in different calls
* Update changelog
* Bring back `any` and `any_service`
* Address review feedback
This addresses something thats been bothering me for some time: Most middleware need to run regardless if the request matches a route or not. For example you don't wanna skip logging for unmatched requests.
However middleware such as authorization only make sense to run for matching requests. This previously wasn't possible to express and you'd have to manually apply the middleware to each handler. Consider this:
```rust
Router::new()
.route("/foo", get(|| async {}))
.layer(RequireAuthorizationLayer::bearer("password"));
```
Calling `GET /foo` with an invalid token would receive `401 Unauthorized` as expected however calling some unknown route like `GET /not-found` would also return `401 Unauthorized`. I think this is unexpected and have seen a few users ask questions about it.
It happened because the 404 you'd otherwise see is generated by a fallback service stored on `Router`. When adding a layer to the router the layer would also be applied to the fallback, which in the case of auth means the fallback would never be called for unauthorized requests.
I think what axum does today is the right default however I still think we should support this somehow. Especially since [`extractor_middleware`](https://docs.rs/axum/0.3.1/axum/extract/fn.extractor_middleware.html) is mainly useful for auth but it doesn't work great today due to this gotcha.
This PR proposes adding `Router::layer_on_matching_route` which only applies layers to routes, not the fallback, which fixes the issue. I'm not a big fan of the name `layer_on_matching_route`, would like something shorter, but I think it communicates the purpose decently.
The generics are a bit different since the request body used on the routes and the fallback must match, so layers that changes the request body type are not compatible with `layer_on_matching_route`. Such middleware are very rare so that should be fine.
* Move axum crate into workspace subfolder
Over time I imagine we're gonna have other crates in this repo that
provide utilities or integrations for axum. This prepares for that by
moving the main axum crate into its own folder.
The README situation is a bit annoying because we want `./README.md`
for viewing the repo on github but `axum/README.md` for crates.io. For
now I've just copy/pasted it and added CI step to make sure they're
identical.
* update changelog link
* Add licenses to all examples
* is this how you install `diff`?
* or maybe this is how?
* fix readme links
* like this?
* fix cargo-deny step
* Try making root readme a symlink
* remove compare readme step
not needed since readme in repo root is now a symlink
* Revert "Add licenses to all examples"
This reverts commit ab321b7fb9.
Kai Jewson