hostname: apply hostname same as is written

on RHEL, we were writing to persistent configuration the fqdn, but
invoking 'hostname' on the first boot with just the shortname.  On 'reboot',
then the hostname would differ.

Now, whatever we write, invoke hostname with.

Also remove some duplicate code.

LP: #1246485

7 files changed, 8 insertions, 36 deletions

diff --git a/ChangeLog b/ChangeLog
index da2a5a0c..ddde383a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,8 @@
  - GCE: Allow base64 encoded user-data (LP: #1404311) [Wayne Witzell III]
  - GCE: use short hostname rather than fqdn (LP: #1383794) [Ben Howard]
  - systemd: make init stage run before login prompts shown [Steve Langasek]
+ - hostname: on first boot apply hostname to be same as is written for
+   persistent hostname.  (LP: #1246485)
 0.7.6:
  - open 0.7.6
  - Enable vendordata on CloudSigma datasource (LP: #1303986)
diff --git a/cloudinit/distros/__init__.py b/cloudinit/distros/__init__.py
index bf465442..5eab780b 100644
--- a/cloudinit/distros/__init__.py
+++ b/cloudinit/distros/__init__.py
@@ -86,7 +86,7 @@ class Distro(object):
     def set_hostname(self, hostname, fqdn=None):
         writeable_hostname = self._select_hostname(hostname, fqdn)
         self._write_hostname(writeable_hostname, self.hostname_conf_fn)
-        self._apply_hostname(hostname)
+        self._apply_hostname(writeable_hostname)
 
     @abc.abstractmethod
     def package_command(self, cmd, args=None, pkgs=None):
@@ -160,9 +160,12 @@ class Distro(object):
             util.logexc(LOG, "Failed to non-persistently adjust the system "
                         "hostname to %s", hostname)
 
-    @abc.abstractmethod
     def _select_hostname(self, hostname, fqdn):
-        raise NotImplementedError()
+        # Prefer the short hostname over the long
+        # fully qualified domain name
+        if not hostname:
+            return fqdn
+        return hostname
 
     @staticmethod
     def expand_osfamily(family_list):
diff --git a/cloudinit/distros/arch.py b/cloudinit/distros/arch.py
index 005a0dd4..68bf1aab 100644
--- a/cloudinit/distros/arch.py
+++ b/cloudinit/distros/arch.py
@@ -118,13 +118,6 @@ class Distro(distros.Distro):
                 return False
         return True
 
-    def _select_hostname(self, hostname, fqdn):
-        # Prefer the short hostname over the long
-        # fully qualified domain name
-        if not hostname:
-            return fqdn
-        return hostname
-
     def _write_hostname(self, your_hostname, out_fn):
         conf = None
         try:
diff --git a/cloudinit/distros/debian.py b/cloudinit/distros/debian.py
index 010be67d..b09eb094 100644
--- a/cloudinit/distros/debian.py
+++ b/cloudinit/distros/debian.py
@@ -86,13 +86,6 @@ class Distro(distros.Distro):
         else:
             return distros.Distro._bring_up_interfaces(self, device_names)
 
-    def _select_hostname(self, hostname, fqdn):
-        # Prefer the short hostname over the long
-        # fully qualified domain name
-        if not hostname:
-            return fqdn
-        return hostname
-
     def _write_hostname(self, your_hostname, out_fn):
         conf = None
         try:
diff --git a/cloudinit/distros/freebsd.py b/cloudinit/distros/freebsd.py
index 9216510e..f1b4a256 100644
--- a/cloudinit/distros/freebsd.py
+++ b/cloudinit/distros/freebsd.py
@@ -150,11 +150,6 @@ class Distro(distros.Distro):
             return default
         return hostname
 
-    def _select_hostname(self, hostname, fqdn):
-        if not hostname:
-            return fqdn
-        return hostname
-
     def _write_hostname(self, hostname, filename):
         self.updatercconf('hostname', hostname)
 
diff --git a/cloudinit/distros/gentoo.py b/cloudinit/distros/gentoo.py
index 45c2e658..09dd0d73 100644
--- a/cloudinit/distros/gentoo.py
+++ b/cloudinit/distros/gentoo.py
@@ -97,13 +97,6 @@ class Distro(distros.Distro):
         else:
             return distros.Distro._bring_up_interfaces(self, device_names)
 
-    def _select_hostname(self, hostname, fqdn):
-        # Prefer the short hostname over the long
-        # fully qualified domain name
-        if not hostname:
-            return fqdn
-        return hostname
-
     def _write_hostname(self, your_hostname, out_fn):
         conf = None
         try:
diff --git a/cloudinit/distros/sles.py b/cloudinit/distros/sles.py
index 9788a1ba..43682a12 100644
--- a/cloudinit/distros/sles.py
+++ b/cloudinit/distros/sles.py
@@ -115,13 +115,6 @@ class Distro(distros.Distro):
         conf.set_hostname(hostname)
         util.write_file(out_fn, str(conf), 0644)
 
-    def _select_hostname(self, hostname, fqdn):
-        # Prefer the short hostname over the long
-        # fully qualified domain name
-        if not hostname:
-            return fqdn
-        return hostname
-
     def _read_system_hostname(self):
         host_fn = self.hostname_conf_fn
         return (host_fn, self._read_hostname(host_fn))