Flaky Test: xds/TestUnmarshalListener_WithUpdateValidatorFunc

[arjan-bal]

Sample run: https://github.com/grpc/grpc-go/actions/runs/10779216338/job/29892227988?pr=7498

Error message:

xds_server_integration_test.go:115: Serve() failed: grpc: the server has been stopped

job-logs.txt

[arjan-bal]

https://github.com/grpc/grpc-go/actions/runs/10779216338/job/29892227988

[easwars]

I think this is what is happening:

• The test starts an xds-enabled gRPC server here:

  grpc-go/test/xds/xds_security_config_nack_test.go

  Line 153 in 8f920c6

  lis, cleanup2 := setupGRPCServer(t, bootstrapContents)

• setupGRPCServer creates an xds-enabled gRPC server and spawns a goroutine to start serving here:

  grpc-go/test/xds/xds_server_integration_test.go

  Line 113 in 8f920c6

  go func() {

• Back in the main test goroutine though, for sub-tests where we expect failures, we create a really short deadline and attempt to make an RPC and expect it to fail.

  grpc-go/test/xds/xds_security_config_nack_test.go

  Line 200 in 8f920c6

  // Make a context with a shorter timeout from the top level test

• What can happen here is that the RPC can fail before the server has stared serving, and the test completes.
• A little later on though, the goroutine to start serving runs, and sees that the server has already been closed.

We need to ensure that the server has started serving before attempting client RPCs.