compatibility fixes for Fedora and RHEL

This patch fixes issues in Fedora 18 (and upcoming RHEL 7) which are
present due to their use of systemd:

 - store locale configuration in /etc/locale.conf
 - store hostname in /etc/hostname
 - use a symlink for /etc/localtime (prior code would set the timezone
   but corrupt data in /usr/share/zoneinfo due to presence of symlink)

It also contains fixes for issues unrelated to systemd adoption:

 - explicitly scan /dev/sr0 with blkid in order to get the optical drive
   in the blkid cache.  This prevents an issue on systems running 2.6
   kernels (such as RHEL 6) in which config disks on some devices won't
   be detected unless the device has previously been queried.
    (For reference, see https://patchwork.kernel.org/patch/1770241/)
 - append a newline when rewriting sysconfig files, as this is customary
   text configuration file formatting and is expected by some parsers
   (such as the ifcfg-rh plugin for NetworkManager)

cloudinit/distros/rhel.py

@@ -47,8 +47,10 @@ class Distro(distros.Distro):
     # See: http://tiny.cc/6r99fw
     clock_conf_fn = "/etc/sysconfig/clock"
     locale_conf_fn = '/etc/sysconfig/i18n'
+    systemd_locale_conf_fn = '/etc/locale.conf'
     network_conf_fn = "/etc/sysconfig/network"
     hostname_conf_fn = "/etc/sysconfig/network"
+    systemd_hostname_conf_fn = "/etc/hostname"
     network_script_tpl = '/etc/sysconfig/network-scripts/ifcfg-%s'
     resolve_conf_fn = "/etc/resolv.conf"
     tz_local_fn = "/etc/localtime"
@@ -143,9 +145,21 @@ class Distro(distros.Distro):
             ]
             if not exists:
                 lines.insert(0, util.make_header())
-            util.write_file(fn, "\n".join(lines), 0644)
+            util.write_file(fn, "\n".join(lines) + "\n", 0644)
+
+    def _dist_uses_systemd(self):
+        # Fedora 18 and RHEL 7 were the first adopters in their series
+        (dist, vers) = util.system_info()['dist'][:2]
+        major = (int)(vers.split('.')[0])
+        return ((dist.startswith('Red Hat Enterprise Linux') and major >= 7)
+                or (dist.startswith('Fedora') and major >= 18))
 
     def apply_locale(self, locale, out_fn=None):
+        if self._dist_uses_systemd():
+            if not out_fn:
+                out_fn = self.systemd_locale_conf_fn
+            out_fn = self.systemd_locale_conf_fn
+        else:
             if not out_fn:
                 out_fn = self.locale_conf_fn
         locale_cfg = {
@@ -154,6 +168,9 @@ class Distro(distros.Distro):
         self._update_sysconfig_file(out_fn, locale_cfg)
 
     def _write_hostname(self, hostname, out_fn):
+        if self._dist_uses_systemd():
+            util.subp(['hostnamectl', 'set-hostname', str(hostname)])
+        else:
             host_cfg = {
                 'HOSTNAME': hostname,
             }
@@ -167,10 +184,20 @@ class Distro(distros.Distro):
         return hostname
 
     def _read_system_hostname(self):
-        return (self.network_conf_fn,
-                self._read_hostname(self.network_conf_fn))
+        if self._dist_uses_systemd():
+            host_fn = self.systemd_hostname_conf_fn
+        else:
+            host_fn = self.hostname_conf_fn
+        return (host_fn, self._read_hostname(host_fn))
 
     def _read_hostname(self, filename, default=None):
+        if self._dist_uses_systemd():
+            (out, _err) = util.subp(['hostname'])
+            if len(out):
+                return out
+            else:
+                return default
+        else:
             (_exists, contents) = self._read_conf(filename)
             if 'HOSTNAME' in contents:
                 return contents['HOSTNAME']
@@ -200,6 +227,12 @@ class Distro(distros.Distro):
         if not os.path.isfile(tz_file):
             raise RuntimeError(("Invalid timezone %s,"
                                 " no file found at %s") % (tz, tz_file))
+        if self._dist_uses_systemd():
+            # Currently, timedatectl complains if invoked during startup
+            # so for compatibility, create the link manually.
+            util.del_file(self.tz_local_fn)
+            util.sym_link(tz_file, self.tz_local_fn)
+        else:
             # Adjust the sysconfig clock zone setting
             clock_cfg = {
                 'ZONE': str(tz),

cloudinit/sources/DataSourceConfigDrive.py

@@ -258,6 +258,9 @@ def find_candidate_devs():
         * labeled with 'config-2'
     """
 
+    # Query optical drive to get it in blkid cache for 2.6 kernels
+    util.find_devs_with(path="/dev/sr0")
+
     by_fstype = (util.find_devs_with("TYPE=vfat") +
                  util.find_devs_with("TYPE=iso9660"))
     by_label = util.find_devs_with("LABEL=config-2")

cloudinit/sources/DataSourceNoCloud.py

@@ -87,6 +87,9 @@ class DataSourceNoCloud(sources.DataSource):
 
         label = self.ds_cfg.get('fs_label', "cidata")
         if label is not None:
+            # Query optical drive to get it in blkid cache for 2.6 kernels
+            util.find_devs_with(path="/dev/sr0")
+
             fslist = util.find_devs_with("TYPE=vfat")
             fslist.extend(util.find_devs_with("TYPE=iso9660"))
 

cloudinit/util.py

@@ -408,6 +408,7 @@ def system_info():
         'release': platform.release(),
         'python': platform.python_version(),
         'uname': platform.uname(),
+        'dist': platform.linux_distribution(),
     }
 
 

tests/unittests/test_datasource/test_configdrive.py

@@ -259,8 +259,9 @@ class TestConfigDriveDataSource(MockerTestCase):
     def test_find_candidates(self):
         devs_with_answers = {}
 
-        def my_devs_with(criteria):
-            return devs_with_answers[criteria]
+        def my_devs_with(*args, **kwargs):
+            criteria = args[0] if len(args) else kwargs.pop('criteria', None)
+            return devs_with_answers.get(criteria, [])
 
         def my_is_partition(dev):
             return dev[-1] in "0123456789" and not dev.startswith("sr")