chore(deps)!: upgrade to tower 0.5

this commit updates our tower dependency from 0.4 to 0.5.

note that this commit does not affect the `tower-service` and
`tower-layer` crates, reëxported by `tower` itself. the `Service<T>`
trait and the closely related `Layer<S>` trait have not been changed.

the `tower` crate's utilities have changed in various ways, some of
particular note for the linkerd2 proxy. see these items, excerpted from
the tower changelog:

- **retry**: **Breaking Change** `retry::Policy::retry` now accepts `&mut Req` and `&mut Res` instead of the previous mutable versions. This
  increases the flexibility of the retry policy. To update, update your method signature to include `mut` for both parameters. ([tower-rs/tower#584])
- **retry**: **Breaking Change** Change Policy to accept &mut self ([tower-rs/tower#681])
- **retry**: **Breaking Change** `Budget` is now a trait. This allows end-users to implement their own budget and bucket implementations. ([tower-rs/tower#703])
- **util**: **Breaking Change** `Either::A` and `Either::B` have been renamed `Either::Left` and `Either::Right`, respectively. ([tower-rs/tower#637])
- **util**: **Breaking Change** `Either` now requires its two services to have the same error type. ([tower-rs/tower#637])
- **util**: **Breaking Change** `Either` no longer implemenmts `Future`. ([tower-rs/tower#637])
- **buffer**: **Breaking Change** `Buffer<S, Request>` is now generic over `Buffer<Request, S::Future>.` ([tower-rs/tower#654])

see:

* <tower-rs/tower#584>
* <tower-rs/tower#681>
* <tower-rs/tower#703>
* <tower-rs/tower#637>
* <tower-rs/tower#654>

the `Either` trait bounds are particularly impactful for us. because
this runs counter to how we treat errors (skewing towards boxed errors,
in general), we temporarily vendor a version of `Either` from the 0.4
release, whose variants have been renamed to match the 0.5 interface.

updating to box the inner `A` and `B` services' errors, so we satiate
the new `A::Error = B::Error` bounds, can be addressed as a follow-on.
that's intentionally left as a separate change, due to the net size of
our patchset between this branch and #3504.

* <tower-rs/tower@v0.4.x...master>
* <https://github.com/tower-rs/tower/blob/master/tower/CHANGELOG.md>

this work is based upon #3504. for more information, see:

* linkerd/linkerd2#8733
* #3504

Signed-off-by: katelyn martin <[email protected]>
X-Ref: tower-rs/tower#815
X-Ref: tower-rs/tower#817
X-Ref: tower-rs/tower#818
X-Ref: tower-rs/tower#819

Author: cratelyn

Cargo.lock

@@ -993,7 +993,7 @@ dependencies = [
  "pin-project",
  "tokio",
  "tokio-test",
- "tower 0.4.13",
+ "tower 0.5.2",
 ]
 
 [[package]]
@@ -1393,7 +1393,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1416,7 +1416,7 @@ dependencies = [
  "serde_json",
  "thiserror 2.0.12",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1485,7 +1485,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1506,7 +1506,7 @@ dependencies = [
  "tokio",
  "tokio-test",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
 ]
@@ -1545,7 +1545,7 @@ dependencies = [
  "tokio",
  "tokio-test",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1581,7 +1581,7 @@ dependencies = [
  "tokio-rustls",
  "tokio-stream",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
  "tracing-subscriber",
 ]
@@ -1629,7 +1629,7 @@ dependencies = [
  "tokio-rustls",
  "tokio-test",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
 ]
@@ -1658,7 +1658,7 @@ dependencies = [
  "tokio-stream",
  "tokio-test",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
  "tracing-subscriber",
 ]
@@ -1835,7 +1835,7 @@ dependencies = [
  "http",
  "linkerd-stack",
  "pin-project",
- "tower 0.4.13",
+ "tower 0.5.2",
 ]
 
 [[package]]
@@ -1854,7 +1854,7 @@ dependencies = [
  "parking_lot",
  "pin-project",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1864,7 +1864,7 @@ version = "0.1.0"
 dependencies = [
  "http",
  "linkerd-stack",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1895,7 +1895,7 @@ dependencies = [
  "http-body",
  "linkerd-stack",
  "pin-project",
- "tower 0.4.13",
+ "tower 0.5.2",
 ]
 
 [[package]]
@@ -1919,7 +1919,7 @@ dependencies = [
  "pin-project",
  "thiserror 2.0.12",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -1973,7 +1973,7 @@ dependencies = [
  "pin-project",
  "thiserror 2.0.12",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
  "try-lock",
 ]
@@ -2009,7 +2009,7 @@ dependencies = [
  "linkerd-tracing",
  "parking_lot",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2212,7 +2212,7 @@ dependencies = [
  "rand 0.9.0",
  "tokio",
  "tokio-test",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
 ]
@@ -2236,7 +2236,7 @@ dependencies = [
  "pin-project",
  "prost 0.13.5",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2254,7 +2254,7 @@ dependencies = [
  "linkerd-stack",
  "rand 0.9.0",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2319,7 +2319,7 @@ version = "0.1.0"
 dependencies = [
  "futures",
  "linkerd-error",
- "tower 0.4.13",
+ "tower 0.5.2",
 ]
 
 [[package]]
@@ -2334,7 +2334,7 @@ dependencies = [
  "linkerd-stack",
  "tokio",
  "tokio-stream",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2377,7 +2377,7 @@ dependencies = [
  "thiserror 2.0.12",
  "tokio",
  "tokio-test",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
  "try-lock",
@@ -2412,7 +2412,7 @@ dependencies = [
  "linkerd-proxy-core",
  "pin-project",
  "thiserror 2.0.12",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2451,7 +2451,7 @@ dependencies = [
  "tokio",
  "tokio-test",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
  "x509-parser",
 ]
@@ -2483,7 +2483,7 @@ dependencies = [
  "thiserror 2.0.12",
  "tokio",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2499,7 +2499,7 @@ dependencies = [
  "pin-project",
  "rand 0.9.0",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
 ]
 
 [[package]]
@@ -2530,7 +2530,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tokio-test",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
 ]
@@ -2542,7 +2542,7 @@ dependencies = [
  "futures",
  "linkerd-error",
  "linkerd-stack",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2584,7 +2584,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tonic",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2609,7 +2609,7 @@ dependencies = [
  "tokio",
  "tokio-test",
  "tokio-util",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
  "tracing",
 ]
@@ -2622,7 +2622,7 @@ dependencies = [
  "parking_lot",
  "tokio",
  "tokio-test",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tower-test",
 ]
 
@@ -2633,7 +2633,7 @@ dependencies = [
  "futures",
  "linkerd-error",
  "linkerd-stack",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -2654,7 +2654,7 @@ dependencies = [
  "pin-project",
  "thiserror 2.0.12",
  "tokio",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
  "untrusted",
 ]
@@ -2720,7 +2720,7 @@ dependencies = [
  "linkerd-stack",
  "rand 0.8.5",
  "thiserror 1.0.69",
- "tower 0.4.13",
+ "tower 0.5.2",
  "tracing",
 ]
 
@@ -4198,10 +4198,14 @@ checksum = "d039ad9159c98b70ecfd540b2573b97f7f52c3e8d9f8ad57a24b916a536975f9"
 dependencies = [
  "futures-core",
  "futures-util",
+ "indexmap 2.8.0",
  "pin-project-lite",
  "sync_wrapper",
+ "tokio",
+ "tokio-util",
  "tower-layer",
  "tower-service",
+ "tracing",
 ]
 
 [[package]]

Cargo.toml

@@ -122,7 +122,7 @@ tokio-rustls = { version = "0.26", default-features = false, features = [
 ] }
 tonic = { version = "0.12", default-features = false }
 tonic-build = { version = "0.12", default-features = false }
-tower = { version = "0.4", default-features = false }
+tower = { version = "0.5", default-features = false }
 tower-service = { version = "0.3" }
 tower-test = { version = "0.4" }
 

linkerd/app/gateway/src/server.rs

@@ -64,10 +64,10 @@ impl Gateway {
                             SessionProtocol::Http1 => http::Variant::Http1,
                             SessionProtocol::Http2 => http::Variant::H2,
                         };
-                        return Ok(svc::Either::A(Http { parent, version }));
+                        return Ok(svc::Either::Left(Http { parent, version }));
                     }
 
-                    Ok(svc::Either::B(Opaq(parent)))
+                    Ok(svc::Either::Right(Opaq(parent)))
                 },
                 opaq,
             )

linkerd/app/inbound/src/accept.rs

@@ -53,12 +53,12 @@ impl<N> Inbound<N> {
                     move |t: T| -> Result<_, Error> {
                         let addr: OrigDstAddr = t.param();
                         if addr.port() == proxy_port {
-                            return Ok(svc::Either::B(t));
+                            return Ok(svc::Either::Right(t));
                         }
 
                         let policy = policies.get_policy(addr);
                         tracing::debug!(policy = ?&*policy.borrow(), "Accepted");
-                        Ok(svc::Either::A(Accept {
+                        Ok(svc::Either::Left(Accept {
                             client_addr: t.param(),
                             orig_dst_addr: addr,
                             policy,