Capture boot panics in debug log.

Docker and Containerd both eat the boot processes stderr, making it difficult
to track down panics (which are always written to stderr).

This CL makes the boot process dup its debug log FD to stderr, so that panics
will be captured in the debug log, which is better than nothing.

This is the 3rd try at this CL.  Previous attempts were foiled because Docker
expects the 'create' command to pass its stdio directly to the container, so
duping stderr in 'create' caused the applications stderr to go to the log file,
which breaks many applications (including our mysql test).

I added a new image_test that makes sure stdout and stderr are handled
correctly.

PiperOrigin-RevId: 215767328
Change-Id: Icebac5a5dcf39b623b79d7a0e2f968e059130059

1 files changed, 21 insertions, 0 deletions

diff --git a/runsc/test/image/image_test.go b/runsc/test/image/image_test.go
index 341bdc1d5..428f05c04 100644
--- a/runsc/test/image/image_test.go
+++ b/runsc/test/image/image_test.go
@@ -303,6 +303,27 @@ func TestRuby(t *testing.T) {
 	}
 }
 
+func TestStdio(t *testing.T) {
+	if err := testutil.Pull("alpine"); err != nil {
+		t.Fatalf("docker pull failed: %v", err)
+	}
+	d := testutil.MakeDocker("stdio-test")
+
+	wantStdout := "hello stdout"
+	wantStderr := "bonjour stderr"
+	cmd := fmt.Sprintf("echo %q; echo %q 1>&2;", wantStdout, wantStderr)
+	if err := d.Run("alpine", "/bin/sh", "-c", cmd); err != nil {
+		t.Fatalf("docker run failed: %v", err)
+	}
+	defer d.CleanUp()
+
+	for _, want := range []string{wantStdout, wantStderr} {
+		if _, err := d.WaitForOutput(want, 5*time.Second); err != nil {
+			t.Fatalf("docker didn't get output %q : %v", want, err)
+		}
+	}
+}
+
 func TestMain(m *testing.M) {
 	testutil.EnsureSupportedDockerVersion()
 	os.Exit(m.Run())