Added Install for gNOI OS service (sonic-net#270)

Author: kanchanavelusamy

host_modules/image_service.py

@@ -219,4 +219,33 @@ def _parse_sonic_installer_list(self, output):
             "current": current_image or "",
             "next": next_image or "",
             "available": available_images or [],
-        }
+        }
+
+    @host_service.method(
+        host_service.bus_name(MOD_NAME), in_signature="as", out_signature="is"
+    )
+    def gnoi_install_os(self, options):
+        """
+        Handles the gNOI OS Install RPC.
+
+        Args:
+            options (str): JSON-formatted InstallRequest from os.proto
+
+        Returns:
+            int: 0 on success
+            str: JSON-encoded InstallResponse with TransferReady or TransferProgress or Validated msg
+        """
+        logger.info("installos: gNOI OS Install RPC called.")
+
+        # Join list of strings into one JSON string
+        request_str = " ".join(options)
+        logger.info("InstallRequest JSON string: %s", request_str)
+
+        try:
+            request_json = json.loads(request_str)
+            logger.info("Parsed InstallRequest: %s", json.dumps(request_json, indent=2))
+        except json.JSONDecodeError as e:
+            logger.error("Failed to parse InstallRequest JSON: %s", e)
+            return 1, f"Invalid InstallRequest JSON: {e}"
+
+        return 1, "ERROR_UNIMPLEMENTED: OS Install not supported"

tests/host_modules/image_service_test.py

@@ -658,3 +658,34 @@ def test_image_set_next_boot_fail_not_exists_generic_rc(self, mock_run, MockInit
             stderr=subprocess.PIPE,
         )
 
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    def test_gnoi_install_os_valid_json(self, MockInit, MockBusName, MockSystemBus):
+        """
+        Test that gnoi_install_os handles valid JSON input and returns ERROR_UNIMPLEMENTED.
+        """
+        image_service = ImageService(mod_name="image_service")
+        options = ['{', '"version": "1.0.0"', '}']  # Valid JSON when joined
+
+        rc, response = image_service.gnoi_install_os(options)
+
+        assert rc == 1
+        assert "ERROR_UNIMPLEMENTED" in response
+
+
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    def test_gnoi_install_os_invalid_json(self, MockInit, MockBusName, MockSystemBus):
+        """
+        Test that gnoi_install_os returns error for invalid JSON input.
+        """
+        image_service = ImageService(mod_name="image_service")
+        options = ['{', '"version": "1.0.0"', 'invalid']  # Invalid JSON
+
+        rc, response = image_service.gnoi_install_os(options)
+
+        assert rc == 1
+        assert "Invalid InstallRequest JSON" in response
+