Add execute_reboot dbus_interface (#164)

As part of sonic-net/sonic-gnmi#286 changes, we require dbus support for executing HALT method.

This PR adds support for execute_reboot for invoking reboot methods.

host_modules/systemd_service.py

@@ -1,12 +1,18 @@
 """Systemd service handler"""
 
+from enum import Enum
 from host_modules import host_service
 import subprocess
 
 MOD_NAME = 'systemd'
 ALLOWED_SERVICES = ['snmp', 'swss', 'dhcp_relay', 'radv', 'restapi', 'lldp', 'sshd', 'pmon', 'rsyslog', 'telemetry']
 EXIT_FAILURE = 1
 
+# Define an Enum for Reboot Methods which are defined as in 
+# https://github.com/openconfig/gnoi/blob/main/system/system.pb.go#L27
+class RebootMethod(Enum):
+    COLD = 1
+    HALT = 3
 
 class SystemdService(host_service.HostModule):
     """
@@ -48,3 +54,19 @@ def stop_service(self, service):
         if result.returncode:
             msg = result.stderr.decode()
         return result.returncode, msg
+
+    @host_service.method(host_service.bus_name(MOD_NAME), in_signature='i', out_signature='is')
+    def execute_reboot(self, rebootmethod):
+        if rebootmethod == RebootMethod.COLD:
+            cmd = ['/usr/local/bin/reboot']
+        elif rebootmethod == RebootMethod.HALT:
+            cmd = ['/usr/local/bin/reboot','-p']
+        else:
+            return EXIT_FAILURE, "{}: Invalid reboot method: {}".format(MOD_NAME, rebootmethod)
+
+        result = subprocess.run(cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        msg = ''
+        if result.returncode:
+            msg = result.stderr.decode()
+
+        return result.returncode, msg

tests/host_modules/systemd_service_test.py

@@ -84,3 +84,57 @@ def test_service_stop_empty(self, MockInit, MockBusName, MockSystemBus):
         ret, msg = systemd_service_stub.stop_service(service)
         assert ret == 1
         assert "stop_service called with no service specified" in msg
+
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    def test_execute_reboot_cold(self, MockInit, MockBusName, MockSystemBus):
+        # Mock subprocess.run
+        with mock.patch("subprocess.run") as mock_run:
+            # Mock the result of subprocess.run
+            res_mock = mock.Mock()
+            test_ret = 0
+            test_msg = b"Succeeded"
+            res_mock.configure_mock(returncode=test_ret, stderr=test_msg)
+            mock_run.return_value = res_mock
+
+            method = systemd_service.RebootMethod.COLD
+            systemd_service_stub = systemd_service.SystemdService(systemd_service.MOD_NAME)
+
+            # Execute the reboot method
+            ret, msg = systemd_service_stub.execute_reboot(method)
+
+            # Assert the correct command was called
+            call_args = mock_run.call_args[0][0]
+            assert "/usr/local/bin/reboot" in call_args, f"Expected 'reboot' command, but got: {call_args}"
+
+            # Assert the return values are correct
+            assert ret == test_ret, f"Expected return code {test_ret}, got {ret}"
+            assert msg == "", f"Expected return message '', got {msg}"
+
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    def test_execute_reboot_halt(self, MockInit, MockBusName, MockSystemBus):
+        # Mock subprocess.run
+        with mock.patch("subprocess.run") as mock_run:
+            # Mock the result of subprocess.run
+            res_mock = mock.Mock()
+            test_ret = 0
+            test_msg = b"Succeeded"
+            res_mock.configure_mock(returncode=test_ret, stderr=test_msg)
+            mock_run.return_value = res_mock
+
+            method = systemd_service.RebootMethod.HALT
+            systemd_service_stub = systemd_service.SystemdService(systemd_service.MOD_NAME)
+
+            # Execute the reboot method
+            ret, msg = systemd_service_stub.execute_reboot(method)
+
+            # Assert the correct command was called
+            call_args = mock_run.call_args[0][0]
+            assert "/usr/local/bin/reboot" in call_args, f"Expected 'reboot' command, but got: {call_args}"
+
+            # Assert the return values are correct
+            assert ret == test_ret, f"Expected return code {test_ret}, got {ret}"
+            assert msg == "", f"Expected return message '', got {msg}"