refactor(app/core): a unit test suite for rescue body #3615

cratelyn · 2025-02-13T03:36:22Z

linkerd-app-core includes an error recovery body middleware. this middleware will gracefully catch and report errors encountered when polling an inner body, and via an R-typed recovery strategy provided by the caller, will attempt to map the error to a gRPC status code denoting an error.

before we upgrade to hyper 1.0 in service of linkerd/linkerd2#8733, we add some test coverage to ensure that we preserve the behavior of this middleware.

see:

for historical context on this tower layer, see:

in #3559 (4b53081), we introduced a backported `Frame<T>` type, and a `ForwardCompatibleBody<B>` type that allows us to interact with a `http_body::Body` circa 0.4.6 in terms of frame-based interfaces that match those of the 1.0 interface. see linkerd/linkerd2#8733 for more information on upgrading hyper. in #3559, we narrowly added this as an internal submodule of the `linkerd-http-retry` library. these facilities however, would have utility in other places such as `linkerd-app-core`. this commit pulls these compatibility shims out into a `linkerd-http-body-compat` library so that they can be imported and reused elsewhere. Signed-off-by: katelyn martin <kate@buoyant.io>

Signed-off-by: katelyn martin <kate@buoyant.io>

these are header values. `http::HeaderName` has a const fn constructor, so let's use that. Signed-off-by: katelyn martin <kate@buoyant.io>

Signed-off-by: katelyn martin <kate@buoyant.io>

we'll add a few tests for this middleware shortly. this commit moves this middleware out into its own submodule. Signed-off-by: katelyn martin <kate@buoyant.io>

for other body middleware, we hide inner enum variants and their constituent members by using the "inner" pattern. this commit tweaks `ResponseBody` to follow suit, such that it now holds an `Inner`, but does not expose its passthrough and rescue variants to callers. Signed-off-by: katelyn martin <kate@buoyant.io>

this adds a small documentation comment describing what this type does. Signed-off-by: katelyn martin <kate@buoyant.io>

this commit introduces a test suite for our error recovery middleware. this body middleware provides a mechanism to "rescue" errors, gracefully mapping an error encountered when polling a gRPC body into e.g. trailers with a gRPC status code. before we upgrade this middleware in service of linkerd/linkerd2#8733, we add some test coverage to ensure that we preserve this middleware. Signed-off-by: katelyn martin <kate@buoyant.io>

this commit makes some minor alterations to our error recovery body middleware. see linkerd/linkerd2#8733 for more information. this commit removes an `assert!` statement from the implementation of `<Response<R, B> as Body>::poll_data()`. see the documentation of `Body::poll_frame()`: > Once the end of the stream is reached, implementations should > continue to return [`Poll::Ready(None)`]. hyperium/http-body@1090bff#diff-33aabe8c2aaa7614022addf244245e09bbff576a67a9ae3c6938c8a868201d36R60-R61 to do this, this commit introduces a distinct terminal state `Inner::Rescued` to represent when the underlying `B`-typed body has yielded an error and been rescued. once in this state the body will yield no more data frames, instead yielding a collection of trailers describing the mid-stream error that was encountered by the underlying body. the call to `R::rescue` is also moved down into the helper function fka `grpc_trailers()`. this helps the function follow the grain of our "state machine" a little more directly. see #3615, #3614, and #3611 for pretext to this change.

this commit makes some minor alterations to our error recovery body middleware. see linkerd/linkerd2#8733 for more information. this commit removes an `assert!` statement from the implementation of `<Response<R, B> as Body>::poll_data()`. see the documentation of `Body::poll_frame()`: > Once the end of the stream is reached, implementations should > continue to return [`Poll::Ready(None)`]. hyperium/http-body@1090bff#diff-33aabe8c2aaa7614022addf244245e09bbff576a67a9ae3c6938c8a868201d36R60-R61 to do this, this commit introduces a distinct terminal state `Inner::Rescued` to represent when the underlying `B`-typed body has yielded an error and been rescued. once in this state the body will yield no more data frames, instead yielding a collection of trailers describing the mid-stream error that was encountered by the underlying body. the call to `R::rescue` is also moved down into the helper function fka `grpc_trailers()`. this helps the function follow the grain of our "state machine" a little more directly. see #3615, #3614, and #3611 for pretext to this change. Signed-off-by: katelyn martin <kate@buoyant.io>

note: this commit will not compile, code changes are intentionally elided from this commit. this commit upgrades hyper, http, tonic, prost, related dependencies, and their assorted cargo features. see <linkerd/linkerd2#8733>. see also: * #3379 * #3380 * #3382 * #3405 * hyperium/hyper#3796 * #3411 * #3421 * #3427 * #3428 * #3432 * #3433 * #3444 * #3445 * #3454 * #3455 * #3456 * #3457 * #3461 * #3459 * #3465 * #3466 * #3467 * #3468 * linkerd/linkerd2-proxy-api#421 * linkerd/linkerd2#13492 * linkerd/linkerd2#13493 * hyperium/hyper#3816 * #3472 * #3473 * #3479 * tokio-rs/tokio#7059 * #3509 * hyperium/http-body#140 * #3515 * hyperium/http-body#141 * #3530 * #3531 * #3540 * #3556 * #3558 * #3559 * #3564 * #3567 * #3573 * #3583 * hyperium/http-body#144 * #3585 * #3586 * #3597 * #3598 * #3611 * #3614 * #3615 * #3616 * #3647 * #3651 * #3653 * #3654 * #3655 * #3656 * #3657 * #3660 * #3671 * #3672 * #3673 * #3676 * hyperium/http-body#147 * #3692 * #3699 * #3700 * #3701 * #3708 * linkerd/drain-rs#36 * #3715 * #3717 * eminence/procfs#340 --- squash: chore(deps): add hyper-util workspace dependency chore(deps): add http-body-util workspace dependency chore(deps): upgrade linkerd2-proxy-api this commit represents main as of linkerd/linkerd2-proxy-api#421. Signed-off-by: katelyn martin <kate@buoyant.io>

## ✨ chore(deps): upgrade to hyperium 1.x crates this branch performs an exciting upgrade for our proxy. this branch upgrades a number of our dependencies so that we use the 1.0 release family of the `hyper` http framework, and its ecosystem. see the [v1.0 announcement][hyper-v1] for more information. this branch upgrades the following dependencies: * `h2`: 0.3 -> 0.4 * `http`: 0.2 -> 1 * `http-body`: 0.4 -> 1 * `hyper`: 0.14.32 -> 1 * `prost`: 0.12 -> 0.13 * `prost-build`: 0.12 -> 0.13 * `prost-types`: 0.12 -> 0.13 * `tonic`: 0.10 -> 0.12 * `tonic-build`: 0.10 -> 0.12 a `hyper-util` dependency is added, which provides among other things, legacy-compatible interfaces such as `hyper_util::client::legacy::Client`, or glue to use `hyper` with the tokio runtime. see <https://docs.rs/hyper-util/latest/hyper_util/> for more information. a `http-body-util` dependency is added, which provides a `BodyExt` trait and a channel-backed body for use in unit tests. the `deprecated` feature flag that was active on our `0.14` hyper dependency has been removed, along with the `stream` and `runtime` feature flags. the `linkerd2-proxy-api` dependency is updated. see: <linkerd/linkerd2-proxy-api#421> ### 📝 notes for review bear particular attention to changes involving `http_body::Body` middleware. the change from two separate `poll_data()` and `poll_trailers()` functions, to a single `poll_frame()` method, induces some subtle changes to various pieces of middleware. also bear in mind that failing to set a timer, in our case `hyper_util::rt::TokioTimer`, can cause http/2 clients, or http/1 and http/2 servers, to panic. make sure that any uses of `hyper::server::conn::http1::Builder`, `hyper::client::conn::http1::Builder`, or `hyper::client::conn::http2::Builder` install a timer. ### ❗ breaking change: `l5d-proxy-error` values the `l5d-proxy-error` header can be examined to observe the cause of proxy errors encountered when sending meshed traffic. by virtue of this using a newer `hyper` client in the proxy, some error messages may in turn look different. for example, an error like `"connect timed out after 1s"` may now appear as `"client error (Connect)"`. ### 📚 other notes this work, by virtue of touching so many parts of the system, is carried out in distinct commits. an initial commit upgrades the dependencies at th workspace level. subsequent commits will not compile if the `--workspace` flag is provided, but the intent of this branch is to update each crate individually. use commands like, e.g. `cargo check --tests -p linkerd-proxy-http` to build particular crates at intermediate commits within this branch. this commit is also only the final leaf in an _extended_ line of work. this has been done to mitigate the effort of reviewing this change, and the risk of churn in the event of any unanticipated errors. see the top-level comment in linkerd/linkerd2#8733 for an overview of all of the work that brought us to this juncture. [hyper-v1]: https://seanmonstar.com/blog/hyper-v1/ --- * chore(deps): upgrade to hyper 1.x note: this commit will not compile, code changes are intentionally elided from this commit. this commit upgrades hyper, http, tonic, prost, related dependencies, and their assorted cargo features. see <linkerd/linkerd2#8733>. see also: * #3379 * #3380 * #3382 * #3405 * hyperium/hyper#3796 * #3411 * #3421 * #3427 * #3428 * #3432 * #3433 * #3444 * #3445 * #3454 * #3455 * #3456 * #3457 * #3461 * #3459 * #3465 * #3466 * #3467 * #3468 * linkerd/linkerd2-proxy-api#421 * linkerd/linkerd2#13492 * linkerd/linkerd2#13493 * hyperium/hyper#3816 * #3472 * #3473 * #3479 * tokio-rs/tokio#7059 * #3509 * hyperium/http-body#140 * #3515 * hyperium/http-body#141 * #3530 * #3531 * #3540 * #3556 * #3558 * #3559 * #3564 * #3567 * #3573 * #3583 * hyperium/http-body#144 * #3585 * #3586 * #3597 * #3598 * #3611 * #3614 * #3615 * #3616 * #3647 * #3651 * #3653 * #3654 * #3655 * #3656 * #3657 * #3660 * #3671 * #3672 * #3673 * #3676 * hyperium/http-body#147 * #3692 * #3699 * #3700 * #3701 * #3708 * linkerd/drain-rs#36 * #3715 * #3717 * eminence/procfs#340 --- squash: chore(deps): add hyper-util workspace dependency chore(deps): add http-body-util workspace dependency chore(deps): upgrade linkerd2-proxy-api this commit represents main as of linkerd/linkerd2-proxy-api#421. Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/box): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(hyper-balance): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/retain): ugrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/stream-timeouts): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/classify): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/upgrade): upgrade to hyper 1.x NOTE: there is a comment noting that the upgrade middleware does not expect to be cloneable. it is unfortunately, however, at odds with the new bounds expected of extensions. so, `Http11Upgrade` is now Clone'able, but a comment is left in place noting this weakened invariant. it's worth investigating how upgrades have changed since, in more detail, but for the current moment we are interested in being especially conservative about changing behavior, and focusing on api changes like `Body::poll_frame(..)`. Signed-off-by: katelyn martin <kate@buoyant.io> * chore(metrics): upgrade to hyper 1.x a brief note; this commit happened to tickle an unfortunate sharp edge in `BoxBody` and `Full`'s respective constructors. type inference could not figure out how to construct the body, so we refrain from boxing the response body now. Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/metrics): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/prom): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/insert): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/retry): deprecate linkerd-http-body-compat Signed-off-by: katelyn martin <kate@buoyant.io> * chore(mock/http-body): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/retry): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(proxy/tap): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(proxy/http): update to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/core): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/test): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/admin): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/outbound): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/inbound): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app/integration): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(app): upgrade to hyper 1.x Signed-off-by: katelyn martin <kate@buoyant.io> * chore(transport-header): update generated code Signed-off-by: katelyn martin <kate@buoyant.io> * chore(spiffe-proto): update generated code Signed-off-by: katelyn martin <kate@buoyant.io> * chore(opencensus-proto): update generated code Signed-off-by: katelyn martin <kate@buoyant.io> * chore(opentelemetry-proto): update generated code Signed-off-by: katelyn martin <kate@buoyant.io> * chore(deny.toml): update cargo-deny directives this commit updates the contents of `deny.toml`. Signed-off-by: katelyn martin <kate@buoyant.io> * chore: `compile` has been renamed to `compile_protos` this addresses deprecation warnings, updating calls to a function that has since been renamed. Signed-off-by: katelyn martin <kate@buoyant.io> * chore(deps): remove `linkerd-http-body-compat` dependencies this commit removes this crate, which we added to future proof code for this upgrade, from its dependents. Signed-off-by: katelyn martin <kate@buoyant.io> * chore(http/body-compat): remove `linkerd-http-body-compat` crate Signed-off-by: katelyn martin <kate@buoyant.io> * chore(deps): update to drain 0.2.1 see linkerd/drain-rs#41. Signed-off-by: katelyn martin <kate@buoyant.io> --------- Signed-off-by: katelyn martin <kate@buoyant.io>

cratelyn added 10 commits February 12, 2025 12:56

nit(http/body-compat): tidy combinators imports

78fe5a3

Signed-off-by: katelyn martin <kate@buoyant.io>

refactor(app/core): hoist errors::code_header helper

961d77b

Signed-off-by: katelyn martin <kate@buoyant.io>

refactor(app/core): l5d-* constants are headers

05eb000

these are header values. `http::HeaderName` has a const fn constructor, so let's use that. Signed-off-by: katelyn martin <kate@buoyant.io>

refactor(app/core): grpc constants are headers

c65cc6c

Signed-off-by: katelyn martin <kate@buoyant.io>

refactor(app/core): hoist l5d- and grpc- constants

61e3bd0

Signed-off-by: katelyn martin <kate@buoyant.io>

refactor(app/core): outline ResponseBody middleware

8d45df5

we'll add a few tests for this middleware shortly. this commit moves this middleware out into its own submodule. Signed-off-by: katelyn martin <kate@buoyant.io>

docs(app/core): document ResponseBody<R, B>

a473d1b

this adds a small documentation comment describing what this type does. Signed-off-by: katelyn martin <kate@buoyant.io>

cratelyn marked this pull request as ready for review February 13, 2025 03:50

cratelyn requested a review from a team as a code owner February 13, 2025 03:50

cratelyn mentioned this pull request Feb 13, 2025

proxy: Figure out the plan for Hyper 1.0 migration linkerd/linkerd2#8733

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Base automatically changed from kate/http-retry.outline-http-body-compat to main February 13, 2025 13:47

olix0r approved these changes Feb 13, 2025

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cratelyn merged commit b883089 into main Feb 13, 2025
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cratelyn deleted the kate/app-core.rescue-body-continues-to-yield-ready-none branch February 13, 2025 15:41

cratelyn mentioned this pull request Feb 14, 2025

refactor(app/core): prepare rescue body for http-body upgrade #3616

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cratelyn mentioned this pull request Feb 14, 2025

chore(deps)!: upgrade to hyper 1.x #3504

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refactor(app/core): a unit test suite for rescue body #3615

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cratelyn commented Feb 13, 2025 •

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refactor(app/core): a unit test suite for rescue body #3615

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