serial: T8375: add CLI option to explicitly set kernel console

Previously, VyOS hardcoded the kernel boot log console to either ttyS0 or
tty0, with no post-install CLI method to change it (manual GRUB edits
were required).

This commit adds a new CLI node:
  system console device <name> kernel

When set, the selected serial console is used as the kernel boot console.
When removed, the kernel boot console falls back to tty0.

1 files changed, 88 insertions, 0 deletions

diff --git a/smoketest/scripts/cli/test_system_console.py b/smoketest/scripts/cli/test_system_console.py
new file mode 100755
index 000000000..388e9236f
--- /dev/null
+++ b/smoketest/scripts/cli/test_system_console.py
@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) VyOS Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import unittest
+
+from base_vyostest_shim import VyOSUnitTestSHIM
+
+from vyos.configsession import ConfigSessionError
+from vyos.system import disk
+from vyos.system.grub import CFG_VYOS_VARS
+from vyos.system.grub import vars_read
+from vyos.xml_ref import default_value
+
+base_path = ['system', 'console']
+serial_console = 'ttyS0'
+default_speed = default_value(base_path + ['device', serial_console, 'speed'])
+
+def get_grub_vars() -> dict:
+    root_dir = disk.find_persistence()
+    vars_file: str = f'{root_dir}/{CFG_VYOS_VARS}'
+    vars_current: dict[str, str] = vars_read(vars_file)
+    return vars_current
+
+class TestSystemConsole(VyOSUnitTestSHIM.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        super(TestSystemConsole, cls).setUpClass()
+
+        # ensure we can also run this test on a live system - so lets clean
+        # out the current configuration :)
+        cls.cli_delete(cls, base_path)
+        cls.cli_commit(cls)
+
+    def tearDown(self):
+        self.cli_delete(base_path)
+        self.cli_commit()
+        # always forward to base class
+        super().tearDown()
+
+    def test_multiple_kernel_consoles(self):
+        self.cli_set(base_path + ['device', 'ttyS1', 'kernel'])
+        self.cli_set(base_path + ['device', 'ttyS2', 'kernel'])
+
+        # Only one console can have 'kernel'
+        with self.assertRaises(ConfigSessionError):
+            self.cli_commit()
+
+    def test_fbcon_and_serial_con_switch(self):
+        if not os.path.exists('/tmp/vyos.smoketests.hint'):
+            self.skipTest('Not running under VyOS CI/CD QEMU environment!')
+
+        grub_vars = get_grub_vars()
+        # we have deleted the CLI config in tearDown() so the default is now
+        # the framebuffer console at tty0
+        self.assertEqual(grub_vars['console_type'], 'tty')
+
+        self.cli_set(base_path + ['device', serial_console, 'kernel'])
+        self.cli_commit()
+
+        grub_vars = get_grub_vars()
+        # We moved the Kernel boot console to ttyS0
+        self.assertEqual(grub_vars['console_type'], serial_console[:-1])
+        self.assertEqual(grub_vars['console_num'], serial_console[-1])
+        self.assertEqual(grub_vars['console_speed'], default_speed)
+
+        self.cli_delete(base_path)
+        self.cli_commit()
+
+        # We moved back to tty as Kernel boot console
+        grub_vars = get_grub_vars()
+        self.assertEqual(grub_vars['console_type'], 'tty')
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2, failfast=VyOSUnitTestSHIM.TestCase.debug_on())