xds/testutils: add fakeTransport for testing. (#8890) This PR introduces `fakeTransport`, a deterministic transport layer designed to facilitate fuzz testing of the xDS client in `grpc-go`. ### Purpose The `fakeTransport` decouples the xDS client from the actual network, allowing tests to simulate management server interactions without establishing real connections. This is a critical component for the upcoming google3-based xdsClient fuzzer, which requires a way to inject specific responses directly into the client. ### Design This component implements the `clients.TransportBuilder`, `clients.Transport` and `clients.Stream` interfaces. * When the `xdsClient` attempts to create a stream, the `Builder` intercepts these calls. Instead of establishing a real connection, it returns a local `FakeTransport` object. * The `FakeStream` replaces the network socket. It exposes standard methods (`Recv`, `Send`) for the xdsClient, and control hooks (`InjectResponse`, `ReadRequest`). Allows the fuzzer to drive the xdsclient's resource parsing by pushing `DiscoveryResponse` protos and inspecting `DiscoveryRequest` messages via buffered channels. ### Future Scope While primarily added for fuzzing, this utility is placed in `internal/testutils` to allow that it can be used by standard unit and e2e tests in the future. Reference: [go/grpc-go-xdsclient-fuzzing](http://goto.google.com/grpc-go-xdsclient-fuzzing) Part of : #8749 RELEASE NOTES: N/A
The Go implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the Go gRPC docs, or jump directly into the quick start.
Simply add the following import to your code, and then go [build|run|test] will automatically fetch the necessary dependencies:
import "google.golang.org/grpc"
Note: If you are trying to access
grpc-gofrom China, see the FAQ below.
The golang.org domain may be blocked from some countries. go get usually produces an error like the following when this happens:
$ go get -u google.golang.org/grpc package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc" (https fetch: Get https://google.golang.org/grpc?go-get=1: dial tcp 216.239.37.1:443: i/o timeout)
To build Go code, there are several options:
Set up a VPN and access google.golang.org through that.
With Go module support: it is possible to use the replace feature of go mod to create aliases for golang.org packages. In your project's directory:
go mod edit -replace=google.golang.org/grpc=github.com/grpc/grpc-go@latest go mod tidy go mod vendor go build -mod=vendor
Again, this will need to be done for all transitive dependencies hosted on golang.org as well. For details, refer to golang/go issue #28652.
Please update to the latest version of gRPC-Go using go get google.golang.org/grpc.
The default logger is controlled by environment variables. Turn everything on like this:
$ export GRPC_GO_LOG_VERBOSITY_LEVEL=99 $ export GRPC_GO_LOG_SEVERITY_LEVEL=info
"code = Unavailable desc = transport is closing"This error means the connection the RPC is using was closed, and there are many possible reasons, including:
It can be tricky to debug this because the error happens on the client side but the root cause of the connection being closed is on the server side. Turn on logging on both client and server, and see if there are any transport errors.