As the proxy's functionality has grown, the HTTP routing functionality
has become complex. Module boundaries have become ill-defined, which
leads to tight coupling--especially around the `ctx` metadata types and
`Service` type signatures.
This change introduces a `Stack` type (and subcrate) that is used as the
base building block for proxy functionality. The `proxy` module now
exposes generic components--stack layers--that are configured and
instantiated in the `app::main` module.
This change reorganizes the repo as follows:
- Several auxiliary crates have been split out from the `src/` directory
into `lib/fs-watch`, `lib/stack` and `lib/task`.
- All logic specific to configuring and running the linkerd2 sidecar
proxy has been moved into `src/app`. The `Main` type has been moved
from `src/lib.rs` to `src/app/main.rs`.
- The `src/proxy` has reusable, generic components useful for building
proxies in terms of `Stack`s.
The logic contained in `lib/bind.rs`, pertaining to per-endpoint service
behavior, has almost entirely been moved into `app::main`.
`control::destination` has changed so that it is not responsible for
building services. (It used to take a clone of `Bind` and use it to
create per-endpoint services). Instead, the destination service
implements the new `proxy::Resolve` trait, which produces an infinite
`Resolution` stream for each lookup. This allows the `proxy::balance`
module to be generic over the servie discovery source.
Furthermore, the `router::Recognize` API has changed to only expose a
`recgonize()` method and not a `bind_service()` method. The
`bind_service` logic is now modeled as a `Stack`.
The `telemetry::http` module has been replaced by a
`proxy::http::metrics` module that is generic over its metadata types
and does not rely on the old telemetry event system. These events are
now a local implementation detail of the `tap` module.
There are no user-facing changes in the proxy's behavior.
This branch changes the proxy's `trust-dns-resolver` dependency to a
version dependency rather than a Git dependency, since the
`0.10.0-alpha.3` version has the features that we previously required
the git dependency for.
The only changes to the proxy codebase itself were fixes for deprecation
warnings introduced by the dependency upgrade, since it was necessary to
update the minimum `tokio_timer` version as `trust-dns-proto` uses APIs
added in `tokio-timer` v0.2.6. In particular, `tokio_timer::Deadline`
was deprecated and replaced by `Timeout`.
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
As we extract subcrates from the `src/` directory, the repository root
becomes a bit cluttered. This change moves these subcrates into a `lib`
directory.
Oliver Gould
Eliza Weisman