[test] dump serial console log for debug purposes

Functional test
"it should not skip any log line even trying to
flood the serial console for QOSGuaranteed VMs"
is generating many sequential log lines over the serial
console fetching the output from k8s log api
and ensuring that all the expected logs lines are
there and in the correct order.

Looking at periodic jobs results the test
is sometimes (~10%) failing due to duplicated
chars in the logs, something like:
```
logline 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195 0006195
loglline 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196 0006196
logline 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197 0006197
```

In case of a failure,
let's collect the console log from virt-launcher
pod with an out-of-band mechanism
to be able to understand if the unexpected chars
was already there in the libvirt generated files.

Signed-off-by: Simone Tiraboschi <[email protected]>

tests/guestlog/guestlog.go

@@ -3,6 +3,8 @@ package guestlog
 import (
 	"context"
 	"fmt"
+	"os"
+	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
@@ -91,6 +93,8 @@ var _ = Describe("[sig-compute]Guest console log", decorators.SigCompute, func()
 		})
 
 		Context("fetch logs", func() {
+			var vmi *v1.VirtualMachineInstance
+
 			var cirrosLogo = `
   ____               ____  ____
  / __/ __ ____ ____ / __ \/ __/
@@ -100,7 +104,7 @@ var _ = Describe("[sig-compute]Guest console log", decorators.SigCompute, func()
 `
 
 			It("it should fetch logs for a running VM with logs API", func() {
-				vmi := tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
+				vmi = tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
 
 				By("Finding virt-launcher pod")
 				virtlauncherPod, err := libvmi.GetPodByVirtualMachineInstance(vmi, testsuite.GetTestNamespace(vmi))
@@ -149,7 +153,7 @@ var _ = Describe("[sig-compute]Guest console log", decorators.SigCompute, func()
 			})
 
 			It("it should rotate the internal log files", func() {
-				vmi := tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
+				vmi = tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
 
 				By("Finding virt-launcher pod")
 				virtlauncherPod, err := libvmi.GetPodByVirtualMachineInstance(vmi, testsuite.GetTestNamespace(vmi))
@@ -179,7 +183,7 @@ var _ = Describe("[sig-compute]Guest console log", decorators.SigCompute, func()
 						k8sv1.ResourceMemory: resource.MustParse("256M"),
 					},
 				}
-				vmi := tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
+				vmi = tests.RunVMIAndExpectLaunch(cirrosVmi, cirrosStartupTimeout)
 				Expect(vmi.Status.QOSClass).ToNot(BeNil())
 				Expect(*vmi.Status.QOSClass).To(Equal(k8sv1.PodQOSGuaranteed))
 
@@ -219,6 +223,23 @@ var _ = Describe("[sig-compute]Guest console log", decorators.SigCompute, func()
 				Expect(matchingLines).To(BeNumerically(">", 1000))
 			})
 
+			AfterEach(func() {
+				if CurrentSpecReport().Failed() {
+					if vmi != nil {
+						virtlauncherPod, err := libvmi.GetPodByVirtualMachineInstance(vmi, testsuite.GetTestNamespace(vmi))
+						if err == nil {
+							artifactsDir, _ := os.LookupEnv("ARTIFACTS")
+							outputString, err := exec.ExecuteCommandOnPod(virtClient, virtlauncherPod, "guest-console-log", []string{"/bin/bash", "-c", "/bin/tail -v -n +1 " + fmt.Sprintf("/var/run/kubevirt-private/%v/virt-serial*-log*", vmi.UID)})
+							if err == nil {
+								lpath := filepath.Join(artifactsDir, fmt.Sprintf("serial_logs_content_%v.txt", vmi.UID))
+								_, _ = fmt.Fprintf(GinkgoWriter, "Serial console log failed, serial console logs dump from virt-launcher pod collected at file at %s\n", lpath)
+								_ = os.WriteFile(lpath, []byte(outputString), 0644)
+							}
+						}
+					}
+				}
+			})
+
 		})
 
 	})