Implement ntp client spec with auto support for distro selection

Add a base NTP client configuration dictionary and allow Distro
specific changes to be merged.  Add a select client function which
implements logic to preferr installed clients over clients which
need to be installed.  Also allow distributions to override the
cloud-init defaults.

LP: #1749722

3 files changed, 55 insertions, 0 deletions

diff --git a/cloudinit/distros/__init__.py b/cloudinit/distros/__init__.py
index 55260eae..6c22b07f 100755
--- a/cloudinit/distros/__init__.py
+++ b/cloudinit/distros/__init__.py
@@ -49,6 +49,9 @@ LOG = logging.getLogger(__name__)
 # It could break when Amazon adds new regions and new AZs.
 _EC2_AZ_RE = re.compile('^[a-z][a-z]-(?:[a-z]+-)+[0-9][a-z]$')
 
+# Default NTP Client Configurations
+PREFERRED_NTP_CLIENTS = ['chrony', 'systemd-timesyncd', 'ntp', 'ntpdate']
+
 
 @six.add_metaclass(abc.ABCMeta)
 class Distro(object):
@@ -60,6 +63,7 @@ class Distro(object):
     tz_zone_dir = "/usr/share/zoneinfo"
     init_cmd = ['service']  # systemctl, service etc
     renderer_configs = {}
+    _preferred_ntp_clients = None
 
     def __init__(self, name, cfg, paths):
         self._paths = paths
@@ -339,6 +343,14 @@ class Distro(object):
             contents.write("%s\n" % (eh))
             util.write_file(self.hosts_fn, contents.getvalue(), mode=0o644)
 
+    @property
+    def preferred_ntp_clients(self):
+        """Allow distro to determine the preferred ntp client list"""
+        if not self._preferred_ntp_clients:
+            self._preferred_ntp_clients = list(PREFERRED_NTP_CLIENTS)
+
+        return self._preferred_ntp_clients
+
     def _bring_up_interface(self, device_name):
         cmd = ['ifup', device_name]
         LOG.debug("Attempting to run bring up interface %s using command %s",
diff --git a/cloudinit/distros/opensuse.py b/cloudinit/distros/opensuse.py
index 162dfa05..9f90e95e 100644
--- a/cloudinit/distros/opensuse.py
+++ b/cloudinit/distros/opensuse.py
@@ -208,4 +208,28 @@ class Distro(distros.Distro):
                                             nameservers, searchservers)
         return dev_names
 
+    @property
+    def preferred_ntp_clients(self):
+        """The preferred ntp client is dependent on the version."""
+
+        """Allow distro to determine the preferred ntp client list"""
+        if not self._preferred_ntp_clients:
+            distro_info = util.system_info()['dist']
+            name = distro_info[0]
+            major_ver = int(distro_info[1].split('.')[0])
+
+            # This is horribly complicated because of a case of
+            # "we do not care if versions should be increasing syndrome"
+            if (
+                (major_ver >= 15 and 'openSUSE' not in name) or
+                (major_ver >= 15 and 'openSUSE' in name and major_ver != 42)
+            ):
+                self._preferred_ntp_clients = ['chrony',
+                                               'systemd-timesyncd', 'ntp']
+            else:
+                self._preferred_ntp_clients = ['ntp',
+                                               'systemd-timesyncd', 'chrony']
+
+        return self._preferred_ntp_clients
+
 # vi: ts=4 expandtab
diff --git a/cloudinit/distros/ubuntu.py b/cloudinit/distros/ubuntu.py
index 82ca34f5..fdc1f622 100644
--- a/cloudinit/distros/ubuntu.py
+++ b/cloudinit/distros/ubuntu.py
@@ -10,12 +10,31 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
 from cloudinit.distros import debian
+from cloudinit.distros import PREFERRED_NTP_CLIENTS
 from cloudinit import log as logging
+from cloudinit import util
+
+import copy
 
 LOG = logging.getLogger(__name__)
 
 
 class Distro(debian.Distro):
+
+    @property
+    def preferred_ntp_clients(self):
+        """The preferred ntp client is dependent on the version."""
+        if not self._preferred_ntp_clients:
+            (name, version, codename) = util.system_info()['dist']
+            # Xenial cloud-init only installed ntp, UbuntuCore has timesyncd.
+            if codename == "xenial" and not util.system_is_snappy():
+                self._preferred_ntp_clients = ['ntp']
+            else:
+                self._preferred_ntp_clients = (
+                    copy.deepcopy(PREFERRED_NTP_CLIENTS))
+        return self._preferred_ntp_clients
+
     pass
 
+
 # vi: ts=4 expandtab