T7101: Add hardware watchdog support via systemd

data/templates/system/watchdog.conf.j2

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+### Autogenerated by system_watchdog.py ###
+[Manager]
+RuntimeWatchdogSec={{ timeout }}
+ShutdownWatchdogSec={{ shutdown_timeout }}
+RebootWatchdogSec={{ reboot_timeout }}

interface-definitions/system_watchdog.xml.in

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+<?xml version="1.0"?>
+<interfaceDefinition>
+  <node name="system">
+    <children>
+      <node name="watchdog" owner="${vyos_conf_scripts_dir}/system_watchdog.py">
+        <properties>
+          <help>Hardware watchdog configuration</help>
+          <priority>9999</priority>
+        </properties>
+        <children>
+          <leafNode name="module">
+            <properties>
+              <help>Kernel module to load for watchdog device (optional)</help>
+              <valueHelp>
+                <format>txt</format>
+                <description>Module name (e.g. 'softdog', 'iTCO_wdt', 'sp5100_tco')</description>
+              </valueHelp>
+              <constraint>
+                <regex>[a-zA-Z0-9_\-]+</regex>
+              </constraint>
+              <constraintErrorMessage>Module name must be alphanumeric/underscore/hyphen</constraintErrorMessage>
+            </properties>
+          </leafNode>
+          <leafNode name="timeout">
+            <properties>
+              <help>Watchdog timeout for runtime in seconds (1-86400)</help>
+              <valueHelp>
+                <format>u32:1-86400</format>
+                <description>Seconds</description>
+              </valueHelp>
+              <constraint>
+                <validator name="numeric" argument="--range 1-86400"/>
+              </constraint>
+              <constraintErrorMessage>Timeout must be between 1 and 86400 seconds</constraintErrorMessage>
+            </properties>
+            <defaultValue>10</defaultValue>
+          </leafNode>
+          <leafNode name="shutdown-timeout">
+            <properties>
+              <help>Watchdog timeout during shutdown in seconds (1-86400)</help>
+              <valueHelp>
+                <format>u32:60-86400</format>
+                <description>Seconds</description>
+              </valueHelp>
+              <constraint>
+                <validator name="numeric" argument="--range 60-86400"/>
+              </constraint>
+              <constraintErrorMessage>Shutdown timeout must be between 60 and 86400 seconds</constraintErrorMessage>
+            </properties>
+            <defaultValue>120</defaultValue>
+          </leafNode>
+          <leafNode name="reboot-timeout">
+            <properties>
+              <help>Watchdog timeout during reboot in seconds (60-86400)</help>
+              <valueHelp>
+                <format>u32:60-86400</format>
+                <description>Seconds</description>
+              </valueHelp>
+              <constraint>
+                <validator name="numeric" argument="--range 60-86400"/>
+              </constraint>
+              <constraintErrorMessage>Reboot timeout must be between 60 and 86400 seconds</constraintErrorMessage>
+            </properties>
+            <defaultValue>120</defaultValue>
+          </leafNode>
+        </children>
+      </node>
+    </children>
+  </node>
+</interfaceDefinition>

smoketest/scripts/cli/test_system_watchdog.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# Copyright VyOS maintainers and contributors <[email protected]>
+#
+# 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.utils.process import cmd
+
+base_path = ['system', 'watchdog']
+
+
+class TestSystemWatchdog(VyOSUnitTestSHIM.TestCase):
+    def tearDown(self):
+        self.cli_delete(base_path)
+        self.cli_commit()
+        super().tearDown()
+
+    def test_enable_watchdog_softdog(self):
+        """Configure watchdog (presence enables) with softdog and check state"""
+        # Presence of 'system watchdog' enables watchdog; set module to softdog
+        self.cli_set(base_path)
+        self.cli_set(base_path + ['module', 'softdog'])
+        self.cli_commit()
+        # Check if softdog module is loaded
+        lsmod = cmd('lsmod')
+        self.assertIn('softdog', lsmod)
+        # Check /dev/watchdog0 exists
+        self.assertTrue(
+            os.path.exists('/dev/watchdog0'), '/dev/watchdog0 does not exist'
+        )
+        # Check systemd config file exists
+        config_path = '/run/systemd/system.conf.d/watchdog.conf'
+        self.assertTrue(
+            os.path.exists(config_path), f"Systemd config file not found: {config_path}"
+        )
+
+    def test_invalid_module_rejected(self):
+        """Verify that a non-existent watchdog module causes commit failure"""
+        # Choose a module name unlikely to exist; include a prefix to avoid collision with real names
+        bogus_module = 'zzzx_watchdog_unit_test_fake'
+        self.cli_set(base_path)
+        self.cli_set(base_path + ['module', bogus_module])
+        # Commit should fail due to verify() raising ConfigError on modprobe dry-run failure
+        with self.assertRaisesRegex(Exception, r"Watchdog module '.*' was not found"):
+            self.cli_commit()
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2, failfast=VyOSUnitTestSHIM.TestCase.debug_on())

src/conf_mode/system_watchdog.py

@@ -0,0 +1,138 @@
+#!/usr/bin/env python3
+#
+# Copyright VyOS maintainers and contributors <[email protected]>
+#
+# 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/>.
+
+from sys import exit
+from pathlib import Path
+
+from vyos.config import Config
+from vyos.template import render
+from vyos.utils.process import call, run
+from vyos import ConfigError
+from vyos import airbag
+
+airbag.enable()
+
+watchdog_config_dir = Path('/run/systemd/system.conf.d')
+watchdog_config_file = Path(watchdog_config_dir / 'watchdog.conf')
+modules_load_directory = Path('/run/modules-load.d')
+modules_load_file = Path(modules_load_directory / 'watchdog.conf')
+WATCHDOG_DEV = Path('/dev/watchdog0')
+
+
+def get_config(config=None):
+    if config:
+        conf = config
+    else:
+        conf = Config()
+    base = ['system', 'watchdog']
+
+    if not conf.exists(base):
+        return None
+
+    watchdog = conf.get_config_dict(
+        base, key_mangling=('-', '_'), get_first_key=True, with_recursive_defaults=True
+    )
+
+    return watchdog
+
+
+def verify(watchdog):
+    if watchdog is None:
+        return None
+
+    module = watchdog.get('module')
+    device_exists = WATCHDOG_DEV.exists()
+
+    # Require a usable watchdog: either device already present or a module provided
+    if not module and not device_exists:
+        raise ConfigError(
+            "No watchdog device found at /dev/watchdog0 and no module configured. "
+            "Either configure 'system watchdog module <name>' or ensure the kernel auto-loads a watchdog driver."
+        )
+
+    # If a module is provided, verify it resolves via modprobe (dry-run)
+    if module:
+        # Dry-run modprobe (-n) in quiet mode (-q) verifies availability without loading
+        rc = run(f'modprobe -n -q {module}')
+        if rc != 0:
+            raise ConfigError(
+                f"Watchdog module '{module}' was not found or cannot be loaded"
+            )
+
+    return None
+
+
+def generate(watchdog):
+    # If watchdog node removed entirely, clean up everything
+    if watchdog is None:
+        watchdog_config_file.unlink(missing_ok=True)
+        modules_load_file.unlink(missing_ok=True)
+        return None
+
+    # Persist kernel module autoload on boot if specified (even if not enabled)
+    module = watchdog.get('module')
+    if module:
+        try:
+            modules_load_directory.mkdir(exist_ok=True)
+            modules_load_file.write_text(f"{module}\n")
+        except Exception as e:
+            print(f"Warning: Failed writing modules-load configuration: {e}")
+    else:
+        # If module option removed, drop persisted autoload file
+        modules_load_file.unlink(missing_ok=True)
+
+    # Try to load kernel module if specified and /dev/watchdog0 is missing
+    if not WATCHDOG_DEV.exists():
+        if module:
+            # Try to load the module using vyos call wrapper for logging/airbag integration
+            try:
+                call(f'modprobe {module}')
+            except Exception as e:
+                print(f"Warning: Could not load watchdog module '{module}': {e}")
+    # Re-check for device
+    if not WATCHDOG_DEV.exists():
+        print(
+            "Warning: /dev/watchdog0 not found. Systemd watchdog will not be enabled."
+        )
+        watchdog_config_file.unlink(missing_ok=True)
+        return None
+
+    # Ensure the directory exists
+    watchdog_config_dir.mkdir(parents=True, exist_ok=True)
+
+    # Pass through configured time values directly as seconds
+    render(str(watchdog_config_file), 'system/watchdog.conf.j2', watchdog)
+
+    return None
+
+
+def apply(watchdog):
+    # Reload systemd daemon to apply/unload the watchdog configuration
+    # The watchdog settings take immediate effect after systemd is reloaded
+    call('systemctl daemon-reload')
+
+    return None
+
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)