improvments to systemd/fedora 18 support

This branch contains fixes found while investigating integration of cloud-init
into oVirt. They're in 3 categories:
 - compatibility with systemd configuration management (as used in Fedora 18)
 - workaround for a 2.6 kernel quirk which prevented 'blkid' from displaying
   /dev/sr0 in some cases
 - writing sysconfig files in typical convention, with a newline preceding EOF,
   to make some parsers happy

ChangeLog

@@ -54,6 +54,8 @@
    python-requests, we get https support (LP: #1067888).
  - make apt-get invoke 'dist-upgrade' rather than 'upgrade' for
    package_upgrade. (LP: #1164147)
+ - improvements for systemd with Fedora 18
+ - workaround 2.6 kernel issue that stopped blkid from showing /dev/sr0
 
 0.7.1:
  - sysvinit: fix missing dependency in cloud-init job for RHEL 5.6 

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"
@@ -143,21 +145,36 @@ 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 not out_fn:
-            out_fn = self.locale_conf_fn
+        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 = {
             'LANG': locale,
         }
         self._update_sysconfig_file(out_fn, locale_cfg)
 
     def _write_hostname(self, hostname, out_fn):
-        host_cfg = {
-            'HOSTNAME': hostname,
-        }
-        self._update_sysconfig_file(out_fn, host_cfg)
+        if self._dist_uses_systemd():
+            util.subp(['hostnamectl', 'set-hostname', str(hostname)])
+        else:
+            host_cfg = {
+                'HOSTNAME': hostname,
+            }
+            self._update_sysconfig_file(out_fn, host_cfg)
 
     def _select_hostname(self, hostname, fqdn):
         # See: http://bit.ly/TwitgL
@@ -167,15 +184,25 @@ 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):
-        (_exists, contents) = self._read_conf(filename)
-        if 'HOSTNAME' in contents:
-            return contents['HOSTNAME']
+        if self._dist_uses_systemd():
+            (out, _err) = util.subp(['hostname'])
+            if len(out):
+                return out
+            else:
+                return default
         else:
-            return default
+            (_exists, contents) = self._read_conf(filename)
+            if 'HOSTNAME' in contents:
+                return contents['HOSTNAME']
+            else:
+                return default
 
     def _read_conf(self, fn):
         exists = False
@@ -200,13 +227,19 @@ class Distro(distros.Distro):
         if not os.path.isfile(tz_file):
             raise RuntimeError(("Invalid timezone %s,"
                                 " no file found at %s") % (tz, tz_file))
-        # Adjust the sysconfig clock zone setting
-        clock_cfg = {
-            'ZONE': str(tz),
-        }
-        self._update_sysconfig_file(self.clock_conf_fn, clock_cfg)
-        # This ensures that the correct tz will be used for the system
-        util.copy(tz_file, self.tz_local_fn)
+        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),
+            }
+            self._update_sysconfig_file(self.clock_conf_fn, clock_cfg)
+            # This ensures that the correct tz will be used for the system
+            util.copy(tz_file, self.tz_local_fn)
 
     def package_command(self, command, args=None, pkgs=None):
         if pkgs is None:

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")