Merge 'scylla_ntp_setup: detect already installed ntp client' from Takuya ASADA

On current implementation, we may re-run ntp configuration even it
already configured.
Also, the system may configured with non-default ntp client, we just
ignoring that and configure with default ntp client.

This patch minimize unnecessary re-configuration of ntp client.
It run in following order:
 1. Check NTP client is already running. If it running, skip setup
 2. Check NTP client is alrady installed. If it installed, use it
 3. If there is non of NTP client package installed,
    - if it's CentOS, install chrony
    - if it's on other distributions, install systemd-timesyncd

Closes #8431

* github.com:scylladb/scylla:
  scylla_ntp_setup: detect already installed ntp client
  scylla_util.py: return bool value on systemd_unit.is_active()

dist/common/scripts/scylla_ntp_setup

@@ -29,6 +29,30 @@ import shutil
 
 from scylla_util import *
 from subprocess import run
+from pathlib import Path
+
+def get_chrony_unit():
+    try:
+        unit = systemd_unit('chronyd')
+    except:
+        unit = systemd_unit('chrony')
+    return unit
+
+def get_chrony_conf():
+    p = Path('/etc/chrony/chrony.conf')
+    if p.exists():
+        return p
+    p = Path('/etc/chrony.conf')
+    if p.exists():
+        return p
+    raise FileNotFoundError('chrony.conf not found')
+
+def get_ntp_unit():
+    try:
+        unit = systemd_unit('ntpd')
+    except:
+        unit = systemd_unit('ntp')
+    return unit
 
 if __name__ == '__main__':
     if os.getuid() > 0:
@@ -40,29 +64,69 @@ if __name__ == '__main__':
                         help='specify subdomain of pool.ntp.org (ex: centos, fedora or amazon)')
     args = parser.parse_args()
 
-    # use systemd-timesyncd
-    if systemd_unit.available('systemd-timesyncd'):
+    target = None
+    if os.path.exists('/lib/systemd/systemd-timesyncd'):
+        if systemd_unit('systemd-timesyncd').is_active():
+            print('ntp is already configured, skip setup')
+            sys.exit(0)
+        target = 'systemd-timesyncd'
+    if shutil.which('chronyd'):
+        if get_chrony_unit().is_active():
+            print('ntp is already configured, skip setup')
+            sys.exit(0)
+        if not target:
+            target = 'chrony'
+    if shutil.which('ntpd'):
+        if get_ntp_unit().is_active():
+            print('ntp is already configured, skip setup')
+            sys.exit(0)
+        if not target:
+            target = 'ntp'
+    if not target:
+        if is_redhat_variant():
+            target = 'chrony'
+        else:
+            target = 'systemd-timesyncd'
+
+    print(f'Use {target} to configure ntp')
+    if target == 'systemd-timesyncd':
+        if not os.path.exists('/lib/systemd/systemd-timesyncd'):
+            # On some distribution, systemd-timesyncd is part of systemd package,
+            # but we can ignore it since systemd must be installed by default.
+            pkg_install('systemd-timesyncd')
         run('timedatectl set-ntp true', shell=True, check=True)
-    # use chrony
-    else:
-        if shutil.which('ntpd'):
-            pkg_uninstall('ntp')
+    elif target == 'chrony':
         if not shutil.which('chronyd'):
             pkg_install('chrony')
-        if is_debian_variant():
-            confpath = '/etc/chrony/chrony.conf'
-            chronyd = 'chrony.service'
-        else:
-            confpath = '/etc/chrony.conf'
-            chronyd = 'chronyd.service'
-        with open(confpath) as f:
+        confp = get_chrony_conf()
+        with confp.open() as f:
             conf = f.read()
         if args.subdomain:
             conf2 = re.sub(r'pool\s+([0-9]+)\.(\S+)\.pool\.ntp\.org', 'pool \\1.{}.pool.ntp.org'.format(args.subdomain), conf, flags=re.MULTILINE)
-            with open(confpath, 'w') as f:
+            with confp.open(confpath, 'w') as f:
                 f.write(conf2)
             conf = conf2
-        chronyd = systemd_unit(chronyd)
+        chronyd = get_chrony_unit()
         chronyd.enable()
         chronyd.restart()
         run('chronyc -a makestep', shell=True, check=True)
+    elif target == 'ntp':
+        if not shutil.which('ntpd'):
+            pkg_install('ntp')
+        if not shutil.which('ntpdate'):
+            pkg_install('ntpdate')
+        confp = Path('/etc/ntp.conf')
+        with confp.open() as f:
+            conf = f.read()
+        if args.subdomain:
+            conf2 = re.sub(r'(server|pool)\s+([0-9]+)\.(\S+)\.pool\.ntp\.org', '\\1 \\2.{}.pool.ntp.org'.format(args.subdomain), conf, flags=re.MULTILINE)
+            with confp.open(confpath, 'w') as f:
+                f.write(conf2)
+            conf = conf2
+        match = re.search(r'^(server|pool)\s+(\S*)(\s+\S+)?', conf, flags=re.MULTILINE)
+        server = match.group(2)
+        ntpd = get_ntpd_unit()
+        ntpd.stop()
+        run(f'ntpdate {server}', shell=True, check=True)
+        ntpd.enable()
+        ntpd.start()

dist/common/scripts/scylla_util.py

@@ -802,7 +802,7 @@ class systemd_unit:
         return run('systemctl {} disable {}'.format(self.ctlparam, self._unit), shell=True, check=True)
 
     def is_active(self):
-        return run('systemctl {} is-active {}'.format(self.ctlparam, self._unit), shell=True, capture_output=True, encoding='utf-8').stdout.strip()
+        return True if run('systemctl {} is-active {}'.format(self.ctlparam, self._unit), shell=True, capture_output=True, encoding='utf-8').stdout.strip() == 'active' else False
 
     def mask(self):
         return run('systemctl {} mask {}'.format(self.ctlparam, self._unit), shell=True, check=True)