vyos.util: "harden" is_systemd_service_running() function

Inspired by the comments of https://unix.stackexchange.com/a/435317 use a more
robust approach. A service can be "active" but not "running" (e.g. restarting
with a configuration error). We can now test if a systemd unit is "activated"
and if it is "running" at all.

>>> from vyos.util import is_systemd_service_active
>>> from vyos.util import is_systemd_service_running
>>> is_systemd_service_active('ssh')
True
>>> is_systemd_service_running('sshd')
False
>>> is_systemd_service_running('ssh')
True

1 files changed, 11 insertions, 3 deletions

diff --git a/python/vyos/util.py b/python/vyos/util.py
index 59f9f1c44..60171746a 100644
--- a/python/vyos/util.py
+++ b/python/vyos/util.py
@@ -805,8 +805,16 @@ def make_incremental_progressbar(increment: float):
     while True:
         yield
 
+def is_systemd_service_active(service):
+    """ Test is a specified systemd service is activated.
+    Returns True if service is active, false otherwise.
+    Copied from: https://unix.stackexchange.com/a/435317 """
+    tmp = cmd(f'systemctl show --value -p ActiveState {service}')
+    return bool((tmp == 'active'))
+
 def is_systemd_service_running(service):
     """ Test is a specified systemd service is actually running.
-    Returns True if service is running, false otherwise. """
-    tmp = run(f'systemctl is-active --quiet {service}')
-    return bool((tmp == 0))
+    Returns True if service is running, false otherwise.
+    Copied from: https://unix.stackexchange.com/a/435317 """
+    tmp = cmd(f'systemctl show --value -p SubState {service}')
+    return bool((tmp == 'running'))