[PATCH] Devices: add LoopbackDevice

[Jan Tluka]

This patch adds implementation of a device class for the loopback device (lo)
so that users can benefit from the common API for the other devices, for
example IP address configuration.

The up() and down() methods are disabled for this type of device as this
breaks connection between the controller and LNST agents during recipe
execution.

Signed-off-by: Jan Tluka <jtluka(a)redhat.com&gt;
---
 lnst/Devices/LoopbackDevice.py | 29 +++++++++++++++++++++++++++++
 lnst/Devices/__init__.py       |  2 ++
 2 files changed, 31 insertions(+)
 create mode 100644 lnst/Devices/LoopbackDevice.py

diff --git a/lnst/Devices/LoopbackDevice.py b/lnst/Devices/LoopbackDevice.py
new file mode 100644
index 00000000..2154897d
--- /dev/null
+++ b/lnst/Devices/LoopbackDevice.py
@@ -0,0 +1,29 @@
+"""
+Defines the LoopbackDevice class.
+
+Copyright 2021 Red Hat, Inc.
+Licensed under the GNU General Public License, version 2 as
+published by the Free Software Foundation; see COPYING for details.
+"""
+
+__author__ = """
+jtluka(a)redhat.com (Jan Tluka)
+"""
+
+import pyroute2
+import logging
+from lnst.Devices.Device import Device
+
+class LoopbackDevice(Device):
+    @Device.name.getter
+    def name(self):
+        return "lo"
+
+    def _create(self):
+        pass
+
+    def up(self):
+        logging.warning("Link state operations on LoopbackDevice are
disallowed")
+
+    def down(self):
+        logging.warning("Link state operations on LoopbackDevice are
disallowed")
diff --git a/lnst/Devices/__init__.py b/lnst/Devices/__init__.py
index 52e4499e..b294ff57 100644
--- a/lnst/Devices/__init__.py
+++ b/lnst/Devices/__init__.py
@@ -1,5 +1,6 @@
 from lnst.Common.DeviceError import DeviceError
 from lnst.Devices.Device import Device
+from lnst.Devices.LoopbackDevice import LoopbackDevice
 from lnst.Devices.BridgeDevice import BridgeDevice
 from lnst.Devices.OvsBridgeDevice import OvsBridgeDevice
 from lnst.Devices.BondDevice import BondDevice
@@ -22,6 +23,7 @@ from lnst.Devices.RemoteDevice import RemoteDevice, remotedev_decorator
 
 device_classes = [
         ("Device", Device),
+        ("LoopbackDevice", LoopbackDevice),
         ("BridgeDevice", BridgeDevice),
         ("OvsBridgeDevice", OvsBridgeDevice),
         ("MacvlanDevice", MacvlanDevice),
-- 
2.26.3