tests: Try to capture screenshot via VNC if serial-console-connection…

… fails

While debugging the failing GitHub Actions (see #278), we noticed that
it might serve useful to have a screenshot of the booted system
available. We can capture such a screenshot via vncsnapshot.

NOTE: we move the files inside `results` only if the directory as such
exists in $PWD, otherwise we'd fail the build when being executed as
`tests/build-vm-and-test.sh test` from inside the grml-debootstrap.git.
This happens when manually reproducing the GH tests, though then
`build-vm-and-test.sh` is supposed to be executed from the parent
directory of the `tests` directory (being the grml-debootstrap.git
checkout).

tests/build-vm-and-test.sh

@@ -34,6 +34,8 @@ fi
 if [ "$1" == "setup" ]; then
   sudo apt-get update
   sudo apt-get -qq -y install curl qemu-system-x86 kpartx python3-pexpect python3-serial
+  # vncsnapshot might not be available, though we don't want to abort execution then
+  sudo apt-get -qq -y install vncsnapshot || true
   [ -x ./tests/goss ] || curl -fsSL https://goss.rocks/install | GOSS_DST="$(pwd)/tests" sh
   # TODO: docker.io
   exit 0

tests/serial-console-connection

@@ -1,6 +1,9 @@
 #!/usr/bin/env python
 import argparse
 import serial
+import os
+import shutil
+import subprocess
 import sys
 import time
 from pexpect import fdpexpect
@@ -25,6 +28,11 @@ parser.add_argument(
     type=int,
     help="Maximum time for finding the login prompt, in seconds",
 )
+parser.add_argument(
+    "--screenshot",
+    default="screenshot.jpg",
+    help="file name for screenshot captured via VNC on error",
+)
 parser.add_argument(
     "--tries",
     default="12",
@@ -74,13 +82,29 @@ def login(ser, hostname, user, password, timeout=5):
     child.expect("%s@%s" % (user, hostname), timeout=timeout)
 
 
+def capture_vnc_screenshot(screenshot_file):
+    if not shutil.which("vncsnapshot"):
+        print("WARN: vncsnapshot not available, skipping vnc snapshot capturing.")
+        return
+
+    print("Trying to capture screenshot via vncsnapshot to", screenshot_file)
+
+    proc = subprocess.Popen(["vncsnapshot", "localhost", screenshot_file])
+    proc.wait()
+    if proc.returncode != 0:
+        print("WARN: failed to capture vnc snapshot :(")
+    else:
+        print("Screenshot file '%s' available" % os.path.abspath(screenshot_file))
+
+
 def main():
     args = parser.parse_args()
     hostname = args.hostname
     password = args.password
     port = args.port
     user = args.user
     commands = args.command
+    screenshot_file = args.screenshot
 
     ser = serial.Serial(port, 115200)
     ser.flushInput()
@@ -116,6 +140,7 @@ def main():
             # after poweroff, the serial device will probably vanish. do not attempt reading from it anymore.
 
     if not success:
+        capture_vnc_screenshot(screenshot_file)
         sys.exit(1)
 
 

tests/test-vm.sh

@@ -114,12 +114,14 @@ if [ "$success" = "0" ] ; then
   exit 1
 fi
 
+RC=0
 "$TEST_PWD"/tests/serial-console-connection \
   --tries 180 \
+  --screenshot "$TEST_PWD/tests/screenshot.jpg" \
   --port "$serial_port" \
   --hostname "$VM_HOSTNAME" \
   --poweroff \
-  "mount -t 9p -o trans=virtio,version=9p2000.L,rw $MOUNT_TAG /mnt && cd /mnt && ./testrunner"
+  "mount -t 9p -o trans=virtio,version=9p2000.L,rw $MOUNT_TAG /mnt && cd /mnt && ./testrunner" || RC=$?
 
 if [ ! -d results ] || [ ! -f ./results/goss.tap ] || [ ! -f ./results/goss.exitcode ]; then
   echo "Running tests inside VM failed for unknown reason" >&2
@@ -133,7 +135,14 @@ fi
 
 echo "Finished serial console connection [timeout=${timeout}]."
 
-mv results/* "$TESTS_RESULTSDIR/"
+# in case of errors we might have captured a screenshot via VNC
+if [ -r "${TEST_PWD}"/tests/screenshot.jpg ] ; then
+  cp "${TEST_PWD}"/tests/screenshot.jpg "${TESTS_RESULTSDIR}"
+fi
+
+if [ -d results ] ; then
+  mv results/* "$TESTS_RESULTSDIR/"
+fi
 
 bailout $RC