Fail cleanly when systemd-networkd is not installed

Author: jonathanspw

netplan_cli/cli/state.py

@@ -434,7 +434,11 @@ def __init__(self, ifname=None, all=False):
                               'Please start it.')
                 sys.exit(1)
             logging.debug('systemd-networkd.service is not active. Starting...')
-            utils.systemctl('start', ['systemd-networkd.service'], True)
+            try:
+                utils.systemctl('start', ['systemd-networkd.service'], True)
+            except subprocess.CalledProcessError:
+                logging.error('systemd-networkd is required for \'netplan status\' functionality')
+                sys.exit(1)
 
         # required data: iproute2 and sd-networkd can be expected to exist,
         # due to hard package dependencies