Attach leaks a goroutine about conmon-rs

[Luap99]

Is conn closed?
Looks like it blocks on read() and I would expect read to return once the connection is closed.

[Luap99]

On a second look not conn must be closed but rather cfg.Streams.Stdin since we read from there.

[saschagrunert]

@Luap99 yeah we also block on read in the tests, but I see that as not critical:

conmon-rs/pkg/client/suite_test.go

Lines 379 to 396 in cc1ea23

	go func() {
	line, err := stdoutBuf.ReadString('\n')
	Expect(err).To(BeNil())
	fmt.Println(line)
	// Stdout test
	line, err = stdoutBuf.ReadString('\n')
	Expect(err).To(BeNil())
	fmt.Println(line)
	Expect(line).To(ContainSubstring("Hello world"))
	}()
	go func() {
	line, err := stderrBuf.ReadString('\n')
	Expect(err).To(BeNil())
	fmt.Println(line)
	Expect(line).To(ContainSubstring("Hello world"))
	}()

Do you consider working on a fix for that?

[Luap99]

I assume cfg.Streams.Stdin is supposed to be closed by the caller, i.e. the test here?

Also the goroutines in the ginkgo tests need a defer GinkgoRecover() at the top in order to work properly, https://onsi.github.io/ginkgo/#mental-model-how-ginkgo-handles-failure

[Luap99]

I know next to nothing about the conmon-rs internal but the test is not working.

change the testAttach function to in order to actually make sure it is executed:

func testAttach(stdinWrite io.Writer, stdoutRead, stderrRead io.Reader) {
	wg := &sync.WaitGroup{}
	wg.Add(3)
	// Stdin
	stdoutBuf := bufio.NewReader(stdoutRead)
	stderrBuf := bufio.NewReader(stderrRead)
	go func() {
		defer GinkgoRecover()
		defer wg.Done()
		_, err := fmt.Fprintf(stdinWrite, "/busybox echo Hello world\r")
		Expect(err).To(BeNil())

		_, err = fmt.Fprintf(stdinWrite, "/busybox echo Hello world >&2\r\n")
		Expect(err).To(BeNil())
		fmt.Println("stdin done")
	}()

	go func() {
		defer GinkgoRecover()
		defer wg.Done()

		// Stdout test
		line, err := stdoutBuf.ReadString('\n')
		Expect(err).To(BeNil())
		fmt.Println(line)
		Expect(line).To(ContainSubstring("Hello world"))

		fmt.Println("stdout done")
	}()

	go func() {
		defer GinkgoRecover()
		defer wg.Done()
		line, err := stderrBuf.ReadString('\n')
		Expect(err).To(BeNil())
		fmt.Println(line)
		Expect(line).To(ContainSubstring("Hello world"))

		fmt.Println("stderr done")
	}()
	wg.Wait()
}

There seems to be at least two problems that I can see:

1. the terminal test cannot work with both stdour/err since a terminal only uses one stream.
   It is failing with and just hangs.

2022-07-21T14:47:14.725434Z ERROR backend:create_container{container_id="7b5d1daad76b330d663e0cb73524170cff34f98a5a4c417ac4455126f5be6927" uuid="17e3bede-4368-4a3e-a2cf-a63e9d39d137"}:listen:read_loop: conmon::terminal: 210: Stdout read loop failure: write to attach endpoints: write to attach endpoint: Broken pipe (os error 32)

2. The test without terminal read the input but never sends any output back and therefore also hangs

[saschagrunert]

@Luap99 thank you for the investigations here. I think we can split-up the tests to test the terminal / non terminal cases in a more separated fashion.

[saschagrunert]

I think the tests are still broken, even with #579. I have to dig more into that.