Merge pull request #19 from plesk/check-service-can-be-enbaled

Add function to check if service can be started

pleskdistup/actions/systemd.py

@@ -82,7 +82,7 @@ class DisablePleskRelatedServicesDuringUpgrade(action.ActiveAction):
     oneshot_services: typing.List[str]
 
     def __init__(self):
-        self.name = "rule plesk services"
+        self.name = "disable plesk related services"
         plesk_known_systemd_services = [
             "crond.service",
             "dovecot.service",
@@ -102,7 +102,9 @@ def __init__(self):
             "sw-cp-server.service",
             "sw-engine.service",
         ]
-        self.plesk_systemd_services = [service for service in plesk_known_systemd_services if systemd.is_service_exists(service)]
+        self.plesk_systemd_services = [
+            service for service in plesk_known_systemd_services if systemd.is_service_startable(service)
+        ]
 
         # Oneshot services are special, so they shouldn't be started on revert or after conversion, just enabled
         self.oneshot_services = [
@@ -111,9 +113,9 @@ def __init__(self):
 
         # We don't remove postfix service when remove it during qmail installation
         # so we should choose the right smtp service, otherwise they will conflict
-        if systemd.is_service_exists("qmail.service"):
+        if systemd.is_service_startable("qmail.service"):
             self.plesk_systemd_services.append("qmail.service")
-        elif systemd.is_service_exists("postfix.service"):
+        elif systemd.is_service_startable("postfix.service"):
             self.plesk_systemd_services.append("postfix.service")
 
     def _prepare_action(self) -> action.ActionResult:

pleskdistup/common/src/systemd.py

@@ -3,7 +3,7 @@
 import typing
 import subprocess
 
-from . import dist, util
+from . import dist, log, util
 
 SYSTEMCTL_BIN_PATH = "/usr/bin/systemctl"
 if dist.get_distro().deb_based:
@@ -24,6 +24,59 @@ def is_service_active(service: str):
     return res.returncode == 0
 
 
+def get_required_services(service: str) -> typing.List[str]:
+    res = subprocess.run(
+        [SYSTEMCTL_BIN_PATH, 'show', '--property', 'Requires', service],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        check=True,
+        universal_newlines=True
+    )
+
+    required_services = [service for service in res.stdout.split('s=')[1].split() if '.service' in service]
+    return required_services
+
+
+def is_service_masked(service: str) -> bool:
+    res = subprocess.run(
+        [SYSTEMCTL_BIN_PATH, 'is-enabled', service],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        check=True,
+        universal_newlines=True
+    )
+    if res.stdout == 'masked':
+        return True
+    return False
+
+
+def is_service_startable(
+        service: str,
+        already_checked: typing.Optional[typing.Set[str]] = None
+        ) -> bool:
+    if not is_service_exists(service):
+        log.debug(f"Service '{service}' doesn't exist")
+        return False
+    if is_service_masked(service):
+        log.debug(f"Service '{service}' can't be started because it is masked")
+        return False
+
+    if already_checked is not None and service in already_checked:
+        return True
+
+    if already_checked is None:
+        already_checked = {service}
+    else:
+        already_checked.add(service)
+
+    required_services = get_required_services(service)
+    for required_service in required_services:
+        if not is_service_startable(required_service, already_checked):
+            log.debug(f"Service '{service}' can't be started because required service '{required_service}' doesn't exist")
+            return False
+    return True
+
+
 def reload_systemd_daemon():
     util.logged_check_call([SYSTEMCTL_BIN_PATH, "daemon-reload"])