refactor(http/retry): outline ForwardCompatibleBody<B>
#3614
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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 <[email protected]>
Signed-off-by: katelyn martin <[email protected]>
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nb: marking this as ready for auto-merge, pending approval... |
sfleen
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`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: * linkerd/linkerd2#8733 * #3614. for historical context on this tower layer, see: * #222 * #1246 * #1282 --- * refactor(http/retry): outline `ForwardCompatibleBody<B>` 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 <[email protected]> * nit(http/body-compat): tidy `combinators` imports Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): hoist `errors::code_header` helper Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): `l5d-*` constants are headers these are header values. `http::HeaderName` has a const fn constructor, so let's use that. Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): grpc constants are headers Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): hoist `l5d-` and `grpc-` constants Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): outline `ResponseBody` middleware 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 <[email protected]> * refactor(app/core): encapsulate `ResponseBody` enum 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 <[email protected]> * docs(app/core): document `ResponseBody<R, B>` this adds a small documentation comment describing what this type does. Signed-off-by: katelyn martin <[email protected]> * refactor(app/core): a unit test suite for rescue body 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 <[email protected]> --------- Signed-off-by: katelyn martin <[email protected]>
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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.
cratelyn
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Feb 14, 2025
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 <[email protected]>
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in #3559 (4b53081), we introduced a backported
Frame<T>type, and aForwardCompatibleBody<B>type that allows us to interact with ahttp_body::Bodycirca 0.4.6 in terms of frame-based interfaces thatmatch 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-retrylibrary. these facilities however, would haveutility in other places such as
linkerd-app-core.this commit pulls these compatibility shims out into a
linkerd-http-body-compatlibrary so that they can be imported andreused elsewhere.