improve the updating of /etc/hosts with correct fqdn when possible

Thanks to Adam Gandalman and Marc Cluet for this fix.

cloudinit/CloudConfig/cc_update_etc_hosts.py

@@ -17,57 +17,60 @@
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import cloudinit.util as util
 from cloudinit.CloudConfig import per_always
-import platform
 import StringIO
 
 frequency = per_always
 
 def handle(name,cfg,cloud,log,args):
-    if not util.get_cfg_option_bool(cfg,"manage_etc_hosts",False):
+    hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
+    fqdn = util.get_cfg_option_str(cfg,"fqdn",cloud.get_hostname(fqdn=True))
+
+    if util.get_cfg_option_bool(cfg,"manage_etc_hosts", True):
+        # manage_etc_hosts not true, update the 127.0.1.1 entry via update_etc_hosts
         log.debug("manage_etc_hosts is not set, checking sanity of /etc/hosts")
-        with open('/etc/hosts', 'r') as etchosts:
-            current_hostname = platform.node()
-            hosts_line = "# Added by cloud-init\n127.0.1.1\t%s.localdomain %s\n" % (current_hostname, current_hostname)
-            need_write = False
-            need_change = True
-            new_etchosts = StringIO.StringIO()
-            for line in etchosts:
-                split_line = [s.strip() for s in line.split()]
-                # skip over malformed /etc/hosts entries
-                if len(split_line) < 2:
-                    continue
-                ip, hostnames = split_line[0], split_line[1:]
-                if ip == "127.0.1.1":
-                    for hostname in hostnames:
-                        if hostname == current_hostname:
-                            need_change = False
-                    if need_change == True:
-                        line = hosts_line
-                        need_change = False
-                        need_write = True
-                new_etchosts.write(line)
-            etchosts.close()
-            if need_change == True:
-                new_etchosts.write(hosts_line)
-                need_write = True
-            if need_write == True:
-                new_etcfile = open ('/etc/hosts','wb')
-                new_etcfile.write(new_etchosts.getvalue())
-                new_etcfile.close()
-            new_etchosts.close()
+        update_etc_hosts(hostname, fqdn, log)
         return
 
+    # manage_etc_hosts is set, render from template file
     try:
-        hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
-        if not hostname:
-            hostname = cloud.get_hostname()
-
         if not hostname:
             log.info("manage_etc_hosts was set, but no hostname found")
             return
 
-        util.render_to_file('hosts', '/etc/hosts', { 'hostname' : hostname })
+        util.render_to_file('hosts', '/etc/hosts', \
+            { 'hostname' : hostname, 'fqdn' : fqdn })
 
     except Exception as e:
         log.warn("failed to update /etc/hosts")
         raise
+
+def update_etc_hosts(hostname, fqdn, log):
+     with open('/etc/hosts', 'r') as etchosts:
+         hosts_line = "# Added by cloud-init\n127.0.1.1\t%s %s\n" % (fqdn, hostname)
+         need_write = False
+         need_change = True
+         new_etchosts = StringIO.StringIO()
+         for line in etchosts:
+             split_line = [s.strip() for s in line.split()]
+             # skip over malformed /etc/hosts entries
+             if len(split_line) < 2:
+                 continue
+             ip, hosts = split_line[0], split_line[1:]
+             if ip == "127.0.1.1":
+                 if sorted([hostname, fqdn]) == sorted(hosts):
+                     need_change = False
+                 if need_change == True:
+                     line = hosts_line
+                     need_change = False
+                     need_write = True
+             new_etchosts.write(line)
+         etchosts.close()
+         if need_change == True:
+             new_etchosts.write(hosts_line)
+             need_write = True
+         if need_write == True:
+             new_etcfile = open ('/etc/hosts','wb')
+             new_etcfile.write(new_etchosts.getvalue())
+             new_etcfile.close()
+         new_etchosts.close()
+     return

cloudinit/DataSource.py

@@ -22,6 +22,7 @@ DEP_NETWORK = "NETWORK"
 
 import UserDataHandler as ud
 import cloudinit.util as util
+import platform
 
 class DataSource:
     userdata = None
@@ -96,20 +97,33 @@ class DataSource:
             return "ubuntuhost"
         return(self.metadata['instance-id'])
 
-    def get_hostname(self):
+    def get_hostname(self, fqdn=False):
+        domain = "localdomain"
         if not 'local-hostname' in self.metadata:
-            return None
+            toks = [ platform.node(), domain ]
+        else:
+            toks = self.metadata['local-hostname'].split('.')
 
-        toks = self.metadata['local-hostname'].split('.')
         # if there is an ipv4 address in 'local-hostname', then
         # make up a hostname (LP: #475354)
         if len(toks) == 4:
             try:
                 r = filter(lambda x: int(x) < 256 and x > 0, toks)
                 if len(r) == 4:
-                    return("ip-%s" % '-'.join(r))
-            except: pass
-        return toks[0]
+                    toks = [ "ip-%s" % '-'.join(r) ]
+            except:
+                pass
+
+        if len(toks) > 1:
+            hostname = toks[0]
+            domain = '.'.join(toks[1:])
+        else:
+            hostname = toks[0]
+
+        if fqdn:
+            return "%s.%s" % (hostname,domain)
+        else:
+            return hostname
 
 # return a list of classes that have the same depends as 'depends'
 # iterate through cfg_list, loading "DataSourceCollections" modules

cloudinit/__init__.py

@@ -452,8 +452,8 @@ class CloudInit:
     def get_mirror(self):
         return(self.datasource.get_local_mirror())
 
-    def get_hostname(self):
-        return(self.datasource.get_hostname())
+    def get_hostname(self, fqdn=False):
+        return(self.datasource.get_hostname(fqdn=fqdn))
 
     def device_name_to_device(self,name):
         return(self.datasource.device_name_to_device(name))

templates/hosts.tmpl

@@ -13,7 +13,7 @@
 #     /etc/cloud/cloud.cfg or cloud-config from user-data
 # 
 ## The value '$hostname' will be replaced with the local-hostname
-127.0.1.1 $hostname
+127.0.1.1 $fqdn $hostname
 127.0.0.1 localhost
 
 # The following lines are desirable for IPv6 capable hosts