Use pip to install systemd-python and update path.

files/build_templates/sonic_debian_extension.j2

@@ -235,6 +235,9 @@ sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y in
 # Mark runtime dependencies as manually installed to avoid them being auto-removed while uninstalling build dependencies
 sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-mark manual gir1.2-glib-2.0 libdbus-1-3 libgirepository-1.0-1 libsystemd0 python3-dbus
 
+# Install systemd-python for SONiC host services
+sudo https_proxy=$https_proxy LANG=C chroot $FILESYSTEM_ROOT pip3 install systemd-python
+
 # Install SONiC host services package
 SONIC_HOST_SERVICES_PY3_WHEEL_NAME=$(basename {{sonic_host_services_py3_wheel_path}})
 sudo cp {{sonic_host_services_py3_wheel_path}} $FILESYSTEM_ROOT/$SONIC_HOST_SERVICES_PY3_WHEEL_NAME

src/sonic-host-services/scripts/sonic-host-server

@@ -15,11 +15,11 @@ from gi.repository import GObject
 
 def find_module_path():
     """Find path for host_moduels"""
-    for path in sys.path:
-        mod_path = path + '/host_modules'
-        if os.path.exists(mod_path):
-            return mod_path
-    return None
+    try:
+        from host_modules import host_service
+        return os.path.dirname(host_service.__file__)
+    except:
+        return None
 
 def register_modules(mod_path):
     """Register all host modules"""