cc_ntp: write template before installing and add service restart

On systems which installed ntp and specified servers or pools in the
config ntpd didn't notice the updated configuration file and didn't
use the correct configuration. Resolve this by rendering the template
first which allows the package install to use the existing
configuration. Additionally add a service restart to handle the case
where ntp does not need to be installed but it may not have started.

Add an integration test to confirm that cc_ntp enables ntp to use the
specific servers and pools in the cloud-config.

LP: #1645644

1 files changed, 22 insertions, 2 deletions

diff --git a/cloudinit/config/cc_ntp.py b/cloudinit/config/cc_ntp.py
index e33032fd..225f898a 100644
--- a/cloudinit/config/cc_ntp.py
+++ b/cloudinit/config/cc_ntp.py
@@ -74,10 +74,19 @@ def handle(name, cfg, cloud, log, _args):
                   "not present or disabled by cfg", name)
         return True
 
-    install_ntp(cloud.distro.install_packages, packages=['ntp'],
-                check_exe="ntpd")
     rename_ntp_conf()
+    # ensure when ntp is installed it has a configuration file
+    # to use instead of starting up with packaged defaults
     write_ntp_config_template(ntp_cfg, cloud)
+    install_ntp(cloud.distro.install_packages, packages=['ntp'],
+                check_exe="ntpd")
+
+    # if ntp was already installed, it may not have started
+    try:
+        reload_ntp(systemd=cloud.distro.uses_systemd())
+    except util.ProcessExecutionError as e:
+        LOG.exception("Failed to reload/start ntp service: %s", e)
+        raise
 
 
 def install_ntp(install_func, packages=None, check_exe="ntpd"):
@@ -90,6 +99,7 @@ def install_ntp(install_func, packages=None, check_exe="ntpd"):
 
 
 def rename_ntp_conf(config=NTP_CONF):
+    """Rename any existing ntp.conf file and render from template"""
     if os.path.exists(config):
         util.rename(config, config + ".dist")
 
@@ -125,4 +135,14 @@ def write_ntp_config_template(cfg, cloud):
 
     templater.render_to_file(template_fn, NTP_CONF, params)
 
+
+def reload_ntp(systemd=False):
+    service = 'ntp'
+    if systemd:
+        cmd = ['systemctl', 'reload-or-restart', service]
+    else:
+        cmd = ['service', service, 'restart']
+    util.subp(cmd, capture=True)
+
+
 # vi: ts=4 expandtab